ALBERT

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): E.A. Zakharova, I.N. Krylenko, A.V. Kouraev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Due to the rapid decline of 〈em〉in situ〈/em〉 observations on river discharge in Arctic regions, evaluation of the continental freshwater input to the Arctic Ocean has become problematic and necessitates the development of alternative approaches based on remote sensing. Radar altimetric satellites have demonstrated high potential for estimation of river water discharge. Compared to polar orbiting altimeters, non-polar orbit satellites have an advantage in temporal sampling. Their greatest drawback, however, is spatial coverage: observations do not cover the low reaches of most parts of Arctic rivers. In this study of the Lena River, we demonstrate a way to overcome this limitation by using a combination of 〈em〉in situ〈/em〉 observations from tributaries and satellite observations in the middle river reaches. The water discharge as well as monthly and annual water flow were evaluated using three virtual stations. Direct combination of the water level from these virtual stations was not possible because of the difference in seasonal amplitude. However, the combination of altimetric discharge from the three independently processed tracks significantly improves the flow retrievals. The accuracy of the monthly water flow estimates at the river outlet is 23%. It increases with the integration time giving 7% for annual flow.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): Weihua Wu, Mingzhao Sun, Xiang Ji, Shuyi Qu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To determine the influence of the Mesozoic Yanshanian orogeny in East Asia on contemporaneous Sr isotopic evolution of seawater, we systematically investigated the weathering profile, riverbed sediment and stream water in mono-lithological small granitic watersheds of the Jiuhua Mountains, Anhui, eastern China. Analysis based on 190 samples from 1 to 2 samplings per month during an entire hydrological year, spanning July 2014 to June 2015, shows that the intra-annual change of Sr concentration is 10–70%, but 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr ratios only exhibit a slight change (0.709148–0.710427). This result indicates that using single sampling data to evaluate the influence of chemical weathering on the 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr ratio evolution of seawater may cause some deviations. The 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr ratio in the small granitic watersheds of the Jiuhua Mountains is 0.709148–0.710427 with an average of 0.710021, which is significantly higher than the lowest value (0.7068, ∼160 Ma) of seawater in the Phanerozoic. During and after this period, the East Asian continent experienced a strong tectonic event — Yanshanian orogeny and formed widespread Jurassic–Cretaceous igneous rocks, such as the Jiuhua Mountains granite in the Yangtze Block. The Yanshanian granites in several main tectonic units in China exhibit high radiogenic Sr characteristics. Combined with the evidence of enhanced chemical weathering during Late Jurassic-Early Cretaceous, the notable increase of the seawater 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr ratio after 160 Ma may be related to the Yanshanian orogeny in East Asia.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418308412-ga1.jpg" width="245" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): Shanshan Deng, Junqiang Xia, Meirong Zhou, Fenfen Lin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recent significant channel evolution in the Jingjiang Reach has raised much attention, particularly the remarkable bank erosion. A coupled model for simulating bed deformation and bank erosion has been proposed in this study, which focuses on the erosion of the bank with a composite structure in the Lower Jingjiang Reach. In order to cover three contributing processes that may interact with each other, the proposed model integrates a one-dimensional morphodynamic module with a two-dimensional module of ground water flow and a bank erosion module for the cantilever failure of a composite riverbank. Model performance was evaluated through a detailed simulation of channel evolution along a 150.8-km subreach in the Jingjiang Reach over the 2005 hydrological year. Satisfying results were obtained from the simulation, showing relatively close agreement between the calculations and measurements in terms of hydrological data at the outlet section, bank erosion sites, longitudinal channel profile and typical cross-sectional profiles. In addition, investigations into temporal changes in bank soil properties and critical overhanging width at cantilever failure demonstrate that there was a seasonal variation in the volumetric water content of bank soil, which increased during the rising and flood periods and then decreased during the recession period, showing an impact on the occurrence timing of cantilever failures. The tensile strength and critical overhanging width had an inverse relationship with the water content, whereas the critical width sharply increased and then decreased during high flows affected by a rapid change in river stage. The temporal distribution of cantilever failure events indicates that cantilever failure primarily occurred in the flood and recession periods. The effects of bed roughness, water content variation and secondary flow on bank erosion were also discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): M. Esteves, C. Legout, O. Navratil, O. Evrard〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉In mountainous catchments, soil erosion and sediment transport are highly variable throughout time and their quantification remains a major challenge for the scientific community. Understanding the temporal patterns and the main controls of sediment yields in these environments requires a long term monitoring of rainfall, runoff and sediment flux. This paper analyses this type of data collected during 7 years (2007–2014), at the outlet of the Galabre River, a 20 km〈sup〉2〈/sup〉 watershed, in south eastern France, representative of meso-scale Mediterranean mountainous catchments.〈/p〉 〈p〉This study is based on a hybrid approach using continuous turbidity records and automated total suspended solid sampling to quantify the instantaneous suspended sediment concentrations (SSC), sediment fluxes, event loads and yields. The total suspended sediment yield was 4661 Mg km〈sup〉−2〈/sup〉 and was observed during flood events. The two crucial periods for suspended sediment transport at the outlet were June and November/December (63% of the total). The analysis of suspended sediment transport dynamics observed during 236 flood events highlighted their intermittency and did not show any clear relationship between rainfall, discharge and SSC. The most efficient floods were characterised by counter-clockwise hysteresis relationships between SSC and discharges. The floods with complex hysteresis were the more productive in the long term, during this measuring period exceeding a decade. Nevertheless, the current research outlines the need to obtain medium-term (five years) continuous time series to assess the range of variations of suspended sediment fluxes and to outline clearly the seasonality of suspended sediment yields. Results suggest the occurrence of a temporal dis-connectivity in meso-scale catchments over short time-scales between the meteorological forcing and the sediment yields estimated at the outlet. These findings have important methodological impacts for modelling and operational implications for watershed management.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): Jian Zhang, Chunling Zhang, Wanli Shi, Yicheng Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The water resources-water environment carrying capacity (WR-WECC) is an important indicator for judging the regional macro-control ability of water resources. The nature-based solutions (NBS) concept is related closely to sustainability, harmonious and green development, resources rational exploitation, coupled human and environment, and ecological protection priority. Participatory water management has necessitated the formation of village water resources committees and/or village environmental committees; while in the case of water management, a participatory approach has resulted in the formation of community water association, domestic water committees, cooperative societies, and various water user groups. The WR-WECC evaluation goal is to find the most appropriate water resources development and utilization to maximize benefits and system efficiency while minimizing costs and trade‐offs. To realize the development and utilization of water resources, water ecological conservation, and water environment protection in Yuetang District, we constructed a dynamic evaluation index system including water resources, water environment and water ecological characteristics, applying the principal component analysis (PCA) method to evaluate the temporal scale variation tendency of WR-WECC, and explore a deep-seated reason based on NBS. The WR-WECC evaluation index system covered 16 indexes belonging to three subsystems of water resource, socioeconomic, and eco-environmental systems. We used Statistical Product and Service Solutions (SPSS) 19.0 software and adopted the improved PCA to integrate the urban economic-social-ecological development of the Xiangjiang (a tributary of the Yangtze River) River Basin. We applied the evaluation index system to analyse the trend variability of WR-WECC of Yuetang District from 2005 to 2015 based on NBS. The WR-WECC of Yuetang District was affected mainly by the urban sewage treatment rate, the water use amount per ten thousand Yuan gross domestic product (GDP), and per capita water resources. In addition to minor fluctuations in 2007 and 2011, the WR-WECC in Yuetang District was generally on the rise year by year and was related to socioeconomic development level, regional water environment comprehensive management, and awareness of water ecological protection. The WR-WECC of the Yuetang District in 2013–2015 was in a Class I (excellent) condition. The temporal variations analysis based on NBS was proposed through a combination of economic-social-ecological values provided by nature-based development and utilization patterns. Based on the relationship among regional water resources, economic society, and eco-environment protection, the paper supplied a WR-WECC improvement strategy that was suitable for the development and utilization of water resources in a water-rich area in south China.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): Klodian Gradeci, Nathalie Labonnote, Edvard Sivertsen, Berit Time〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study employs a systematic literature review to investigate how insurance data can be applied in the analysis of Surface Water Flood events. The study firstly identifies the variables expressing insurance data and those explaining them, together with their interrelationships. Damage variables may be expressed as either monetary-based or number of claims-based. Explaining variables may be subdivided into four categories: meteorological, geographic, demographic and property/building-based. Most of the common and under-researched combinations of these variables and their expression are discussed. Secondly, a comparative analysis is presented of current models, highlighting their differences and similarities. The study demonstrates that the scope and approach of the models varies in relation to scale, the coverage and period of incorporated insurance claims, and the methods used for model development and validation. Thirdly, the study proposes a generic and adaptable framework, constructed from an aggregation of information contained in relevant literature, to define a workflow for model development and future deployment. The study concludes with a discussion of the challenges facing model development and opportunities for deployment.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): G.W. Ma, H.D. Wang, L.F. Fan, Y. Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A unified pipe-network-based numerical manifold method (NMM) is developed to simulate immiscible two-phase flow in a geological medium. Both heterogeneous and non-heterogeneous geological media can be discretized as numerical pipe networks, which have high efficiency and accuracy in simulating fluid and mass transfer in fractured rock masses. A manifold element method is developed to solve the governing equations of immiscible two-phase flow in pipes. The developed NMM can simulate moving and deforming of two-phase flow interface. A grid-based front-tracking method updates the marker points constructing the fluid interface explicitly in each time step. The effectiveness of the NMM is verified through analytical and finite element analysis. Parametric studies are conducted by simulating immiscible two-phase flows with various fluid properties in homogeneous and inhomogeneous geological conditions. The results show that the developed method can efficiently simulate the moving interface of two-phase flow in geological media, including effects such as “viscous fingering”, a noteworthy phenomenon in enhanced oil recovery. When the mobility of the driving fluid is larger than that of the driven fluid, the inhomogeneity of the medium can cause the fluid interface to roughen, which increases over time during the process of two-phase flow. For the inverse situation, although the fluid interface remains rough, the roughness variation throughout the process is not prominent.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): Yong Yang, Rensheng Chen, Yaoxuan Song, Chuntan Han, Junfeng Liu, Zhangwen Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mountainous regions are important sources of freshwater. Measurement of actual evapotranspiration (ET) is difficult to obtain in high mountain regions because of the harsh natural environment, and potential ET (PET) is therefore a suitable term to describe the atmospheric water demand of land surfaces under given meteorological conditions in those high elevation areas. In situ measured meteorological data were collected in 2015 and 2016 from five meteorological stations at various elevations from 2980 m to 4484 m in the Qilian Mountains, northwestern China, and the meteorological factors changed markedly with elevation. PET calculated with the Penman method showed a significant elevational gradient, and decreased as the elevation increased. The sensitivity analysis indicated that over the whole period, PET in the research region was most sensitive to net radiation (RN), followed by relative humidity (RH), air temperature (T), wind speed (WS) and soil heat flux (G). When RN was positive, the sensitivity of PET to RN decreased as the elevation increased, and when RN was negative, the sensitivity increased as the elevation increased. When T was above 0 °C, the sensitivity of PET to T decreased as the elevation increased, and when T was below 0 °C, the sensitivity increased as the elevation increased. The higher the elevation, the greater the sensitivity of PET to both RH and WS. The topographic shading in mountainous regions affected meteorological factors, PET and its sensitivity to meteorological factors in those high elevation areas. The RN was relatively small at the sites with topographic shading because of the reduction in solar radiation, and resulted in less sensitivity of PET to RN and greater sensitivity of PET to other meteorological factors. This study can help us to understand PET in the Qilian mountains and in other mountain regions from which meteorological data are difficult to obtain and very sensitive to climate change.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): Davood Mahmoodzadeh, Mohammad Karamouz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Coastal flooding due to storm surge and sea-level rise (SLR) affects seawater intrusion (SWI) in aquifers. Under coastal flooding events, SWI from both sea boundary and land-surface is expected to increase. SWI in coastal aquifers is also strongly influenced by geological heterogeneity characteristics. In this study, the combined impacts of fully geological heterogeneity and coastal flooding on SWI is quantified in a two-dimensional unconfined coastal aquifer. Three indices including the seawater toe location (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉x〈/mi〉〈mrow〉〈mi mathvariant="italic"〉toe〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉), the mixing volume (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉v〈/mi〉〈mrow〉〈mi mathvariant="italic"〉mv〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉) and the SWI volume (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉v〈/mi〉〈mrow〉〈mi mathvariant="italic"〉swiv〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉) are used to assess the vulnerability to the intrusion of the seawater. A series of 50 log-normally distributed random hydraulic conductivity with a spherical correlation function is generated using the GCOSIM3D code. Then, numerical simulations of transient, saturated-unsaturated variable-density flow and solute transport, SUTRA, are performed in a stochastic Monte Carlo framework to understand how coastal flooding and geological heterogeneity effects can change the groundwater salinity.〈/p〉 〈p〉During storm surge events, seawater penetrates into the aquifer and leads to reduce temporary of the freshwater quality. The results indicate that the storm surge has a short-term impact on fresh groundwater. The aquifer is significantly influenced by SLR as a long-term effect while it causes a larger 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉x〈/mi〉〈mrow〉〈mi mathvariant="italic"〉toe〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 in comparison with pre-flooding events’ conditions. Also, the results obtained under gradual and instantaneous assumption of SLR show that the gradual assumption leads to a smaller 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉x〈/mi〉〈mrow〉〈mi mathvariant="italic"〉toe〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 which is more realistic. Comparison of the homogeneous and heterogeneous scenarios indicates the heterogeneity affects SWI status both in the presence and the absence of coastal flooding events. It causes reduction in 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉x〈/mi〉〈mrow〉〈mi mathvariant="italic"〉toe〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉v〈/mi〉〈mrow〉〈mi mathvariant="italic"〉swiv〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉 as well as increase in 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈mrow〉〈msub〉〈mi〉v〈/mi〉〈mrow〉〈mi mathvariant="italic"〉mv〈/mi〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉. This study shows the significant value of considering a wide range of variations due to heterogeneity, in order to better manage the coastal fresh groundwater aquifers.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418308679-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): Zarema Akhmadiyeva, Iskandar Abdullaev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The study explores the shifts in water management paradigms in the Caspian Sea basin over the last three centuries with an emphasis on the period after 1990. The investigation is based on the chronological analysis of developments in the water sector, treaties and agreements between the littoral states, important technical inventions, and changes in political regimes. The methodology used in the paper captures two concepts. The concept of water management paradigms helps to comprehend developmental stages of water management of the Caspian Sea. The concept of hydrosocial cycle was applied as an analytical lens for studying each paradigm. We examine different understandings of water in the following five stages: i) pre-industrial era (before 1846); ii) industrialization era (1846–1917); iii) Soviet collectivization era (1917–1940); iv) hydraulic mission (1940–1990); v) independent littoral states (1990–present). Before the Industrial Revolution, the Caspian Sea was managed by the Russian Empire and Persia for navigation and fishing only. The ensuing technical progress gave an impulse to regional sectoral activities, pushing forward the hydraulic mission that caused a considerable degradation of the sea’s ecosystems. The adoption of the Tehran Convention in 2003 became a first step towards the Integrated Water Resources Management (IWRM) paradigm for the Caspian. However, the water governance of the Caspian states does not adhere to the principles of IWRM and, consequently, environment continues to deteriorate. The study provides new directions and approaches for reviewing the role of society in the governance of the Caspian Sea and its resources.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): Di Wu, Yuanlai Cui, Xianhong Xie, Yufeng Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉According to the hydrological characteristics of a multi-source irrigation system with paddy rice, the Soil and Water Assessment Tool (SWAT) is improved to develop a distributed hydro-agronomic model. A technique with three critical depths is incorporated to control the irrigation and drainage of paddy fields. In addition, the evapotranspiration (ET) of a paddy field is estimated based on two types of water storage conditions within SWAT. Specifically, we propose a multi-source auto-irrigation framework for SWAT to estimate agricultural irrigation water consumptions (AIWCs) from different water sources. Furthermore, we apply the improved SWAT to the Yangshudang (YSD) basin, located in the Zhanghe Irrigation System (ZIS) of southern China, and the simulation results are compared with the observed data as well as with those of the original SWAT. The results indicate that compared with the original SWAT, the Nash-Sutcliffe efficiency (NSE) of daily discharge increases from 0.48 to 0.80 in the calibration period and from 0.68 to 0.84 in the validation period; in addition, the NSE of the daily ET increases from −0.09 to 0.90, and other evaluation metrics also increase. Moreover, the percent bias (PBIAS) between the total AIWC simulated by the improved SWAT and the observed value is 2.75%, and that is −48.59% for the original SWAT. In particular, the improved SWAT estimates AIWCs from local water sources (ponds and rivers) and the main Zhanghe Reservoir, and the simulated AIWCs approximate the observed values. Therefore, the improved SWAT is more effective and suitable for the simulation of hydrological processes than the original SWAT in the multi-source irrigation systems with paddy rice, and it can estimate the AIWCs from different water sources, which can provide irrigation management decision support for irrigation managers.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 568〈/p〉 〈p〉Author(s): Maria C. Neves, Sonia Jerez, Ricardo M. Trigo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Under the increasing risk of water scarcity, aquifer management strategies can take advantage of a deeper knowledge about the natural long-term fluctuations driven by climate patterns. This study examines the links between major large-scale atmospheric circulation modes and inter-annual to decadal oscillations in groundwater levels in Portugal. Precipitation and piezometric records (1987–2016) from two aquifer systems, Leirosa-Monte Real in the north and Querença-Silves in the south, are analyzed using wavelet transform methods and singular spectral analysis. Wavelet coherences computed between hydrologic time series and the North Atlantic Oscillation (NAO), East Atlantic (EA) and Scandinavia (SCAND) climate patterns show non-stationary relationships that are nonetheless consistent in distinct period bands. The strongest covariability occurs in the 6–10 years band for NAO, in the 2–4 years band for EA (especially after 1999) and in the 4–6 years band for SCAND (mainly after 2005). NAO is the mode playing the most relevant role with a stronger influence in the south (60% on average) than in the north (40% on average). The relatively higher frequency (〈5 year period) contributions of EA and SCAND are difficult to set apart but their joint impact accounts for approximately 20% and 40% of the total variance of groundwater levels in the south and north of the country, respectively. Wavelet coherence patterns also expose transitive couplings between NAO, EA and SCAND. Often, coupled phases between climate modes mark abrupt transitions in synchronization patterns and shifts in the time-frequency domain. Extremes in groundwater storage coincide with anti-phase NAO and EA combinations: maximum piezometric levels occur during NAO-EA+ (coincidentally also SCAND+) phases while minimum levels occur during NAO+EA− phases.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): Federica Remondi, Martina Botter, Paolo Burlando, Simone Fatichi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The time that rainfall takes to reach the outlet of a catchment as discharge (transit time) is a fundamental and integrated measure of catchment hydrological processes and solute transport mechanisms. As such, many efforts have been dedicated to its understanding and quantification. However, defining and ranking which factors, internal and external to the system, control the distributions of transit time is still an open challenge. Here, we develop a two-stage approach to explore climate and topography controls on transit time, using a fully distributed hydrological model coupled with a transport component. Specifically, we apply the model to two synthetic topographies under five observed climate regimes. With this setup, water fluxes from two years of daily rainfall events are singularly tracked across the catchments to then derive the distributions of transit time and fraction of young water for each combination of topography and climate. Results highlight a considerable variability of transit times in all climates and a pronounced effect of topography within a given climate. They further reveal that for wet climates it is possible to define a curve describing water transit time as a function of cumulative discharge that only depends on topographic properties. On the contrary, in dry climates the variability of transit time and young water fraction is much larger and not amenable to a simple summary. Despite simplifications, quantitative model-based inferences of transit time distributions are useful to better understand how climate and topography affect catchment functioning.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): Yuzhong Yang, Qingbai Wu, Huijun Jin, Qingfeng Wang, Yadong Huang, Dongliang Luo, Shuhui Gao, Xiaoying Jin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Climatic warming has resulted in permafrost degradation and it is expected to alter the hydrological processes and hydraulic connectivity on the Qinghai-Tibet Plateau (QTP). Some important and pending issues for understanding the hydrological processes in permafrost regions are how much melting water from thawing permafrost can feed the stream water and how the hydraulic connectivities will be altered under continual permafrost degradation. In this study, the Source Area of the Yellow River locating on the Northeast QTP was studied by using stable isotopic method and field hydrological observation. Results exhibited significant seasonal hydrological variations of stream water, thermokarst lakes, and ground ice. Hydrograph separation suggested that precipitation is the main contributor to stream water in ice-free months, accounting for 53.5% and 52.2% of the streams on average for the two branches, respectively. The second source is springs, which contributed about 29.8% and 17.9%. However, the recharge from melting ice is also important; it exported an average of 16.7% and 13.2% to the surface stream. Conceptual model and stable isotopes emphasized the remarkable hydraulic connectivities between the precipitation, stream water, thermokarst lakes, spring, and the near-surface ground ice. Current findings provide a basic understanding of the log-term hydrological processes under permafrost degradation, and can offer an efficient way to assess future hydrological changes and water resource protection.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): Qinggao Feng, Hongbin Zhan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An analytical model for describing pumping induced drawdown by constant-head test at a partially penetrating well in a leaky confined aquifer is developed by treating the leakage of aquitard storage as an interface phenomenon rather than an volumetric effect, which is the novel and never developed so far. Three different cases of remote lateral boundaries are considered in the model. The new drawdown solution in Laplace space is obtained and inverted into time-domain solution utilizing the Stehfest method. The (semi-)analytical solutions for well discharge are then obtained under three different cases. Analytical solutions in Laplace and time domains are developed for calculating the (total) leakage rate and volume across the aquitard-aquifer interface due to constant-head test at a partially penetrating well in a leaky confined aquifer, and such solutions are of great use for groundwater resource management. Based on the newly developed solutions, the distribution of wellbore flowrate and aquitard leakage are explored and the sensitivity analysis is conducted to identify the most important controlling factor. The sensitivity analysis shows that the wellbore flowrate and the drawdown in infinite (Case 1), finite (Case 2), and closed (Case 3) leaky confined aquifer systems are both sensitive to the variation of well partial penetration, well radius, and aquifer anisotropic ratio during the whole pumping period and they are most sensitive to the change of outer boundary distance at late time for Case 3. The effect of the outer boundary on the drawdown or wellbore flowrate is more significant for a shorter outer boundary distance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): Pierre Jeanne, Tom G. Farr, Jonny Rutqvist, Donald W. Vasco〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The center of the San Joaquin Valley is one of the most productive agricultural regions in the US. Farmers rely heavily on surface-water diversions to meet irrigation water demand. However, the 2007–2010 and 2012–2017 droughts have caused strong increases in groundwater pumping causing land subsidence with strong variability in location, magnitude (total subsidence) and rate of subsidence. In this study, we try to understand what caused these variations. We focus our analyses on three areas: (i) the Westland water district where subsidence was very small during the two drought periods, (ii) ‘El Nido’ area where the greatest subsidence rate was monitored from 2008 to 2010, and (iii) the’ Kings-Tulare counties’ area where the subsidence was small during the 2008–2010 and the largest during 2015–2017 droughts. Our main finding is that land subsidence is located in areas where the water demand for agriculture and the density of groundwater wells is the highest, whereas the rate of subsidence is strongly affected the amount of local and imported surface water and by groundwater resources. Based on these simple observations, we propose using continuous satellite-based ground deformation monitoring and geomechanical modeling to (i) localize areas most prone for future subsidence and (ii) to estimate and manage groundwater resources.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): Zhiyong Huang, Pat J.-F. Yeh, Yun Pan, Jiu Jimmy Jiao, Huili Gong, Xiaojuan Li, Andreas Güntner, Yunqiang Zhu, Chong Zhang, Longqun Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The 2003–2013 monthly groundwater storage (GWS) anomalies in the highly karstic region (HKR) and low karstic region (LKR) in the Southwest China are estimated from the Gravity Recovery and Climate Experiment (GRACE) terrestrial water storage (TWS) data by using the ancillary data of surface water storage (SWS) and soil moisture storage (SMS) from the WaterGAP model simulations. The leakage errors in the estimated GWS anomalies are corrected through using the iterative forward modelling approach. The estimated GWS anomalies compare well with in situ groundwater-level observations with the correlation coefficient 〈em〉r〈/em〉 = 0.71 and the root-mean-square-error (RMSE) = 42 mm. For both HKR and LKR, ∼60% of temporal variability of TWS is contributed by GWS variability, while SMS contributes to 18% (HKR) and 28% (LKR), and SWS contributes to 22% (HKR) and 14% (LKR) of the TWS variability. Due to the higher permeability of the epi-karst zones and their better connection with the subsurface aquifers, GWS anomalies in HKR show larger correlations with SWS (〈em〉r〈/em〉 = 0.73, RMSE = 51 mm) and SMS (〈em〉r〈/em〉 = 0.68, RMSE = 47 mm) and a shorter lag to precipitation than that in LKR (SWS: 〈em〉r〈/em〉 = 0.56, RMSE = 50 mm, and SMS: 〈em〉r〈/em〉 = 0.48, RMSE = 49 mm). During the extreme drought in 2009, GWS loss in HKR (LKR) was 74.3 mm/yr (42.7 mm/yr), accounting for 66% (62%) of total TWS loss. The severe GWS loss was mainly due to larger discharges through the well-developed subsurface drainage system rather than human depletion, since groundwater resources are still under-exploited in Southwest China (∼4 km〈sup〉3〈/sup〉/yr, 12% of the potentially exploitable amounts). A quicker recovery of GWS from 2009 drought can be observed in HKR than LKR due to the larger and earlier (approximately one month) precipitation and infiltration, and quicker response of groundwater to precipitation in HKR.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): Dedi Liu, Shenglian Guo, Pan Liu, Lihua Xiong, Hui Zou, Jing Tian, Yujie Zeng, Youjiang Shen, Jiayu Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Water and energy are considered as the two most important resources for human life and development, and can be represented by the nexus for the cross-sectional connection including water supply, wastewater treatment and hydropower generation sectors in a cascade reservoir system. In order to quantify interactions of the nexus, a novel diagram according to water and energy flow in every sector was proposed in this paper. And an optimal water-energy nexus model was also developed for the efficiently and effectively cross-sectoral coordinating the diagram based on the water and energy flow conceptual network. According to our case study in the middle-lower Lancangjiang River basin, the nexus varies with the external water demand, water inflow conditions, instream ecological water demand constraints and the requirements of the electronic grid in the system. Moreover, the objective preferred by the decision maker only slightly influences the nexus results. The proposed approaches including the water-energy nexus diagram and its optimisation model are easily implemented and clearly visually illustrate the process of water and energy flow for every sector. The results of our optimal nexus configuration in the case study not only demonstrate the sensitivity of the parameters and input variables, but can also improve the understanding of the gap between current and optimal situations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): Trine Enemark, Luk J.M. Peeters, Dirk Mallants, Okke Batelaan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Hydrogeological conceptual models are collections of hypotheses describing the understanding of groundwater systems and they are considered one of the major sources of uncertainty in groundwater flow and transport modelling. A common method for characterizing the conceptual uncertainty is the multi-model approach, where alternative plausible conceptual models are developed and evaluated. This review aims to give an overview of how multiple alternative models have been developed, tested and used for predictions in the multi-model approach in international literature and to identify the remaining challenges.〈/p〉 〈p〉The review shows that only a few guidelines for developing the multiple conceptual models exist, and these are rarely followed. The challenge of generating a mutually exclusive and collectively exhaustive range of plausible models is yet to be solved. Regarding conceptual model testing, the reviewed studies show that a challenge remains in finding data that is both suitable to discriminate between conceptual models and relevant to the model objective.〈/p〉 〈p〉We argue that there is a need for a systematic approach to conceptual model building where all aspects of conceptualization relevant to the study objective are covered. For each conceptual issue identified, alternative models representing hypotheses that are mutually exclusive should be defined. Using a systematic, hypothesis based approach increases the transparency in the modelling workflow and therefore the confidence in the final model predictions, while also anticipating conceptual surprises. While the focus of this review is on hydrogeological applications, the concepts and challenges concerning model building and testing are applicable to spatio-temporal dynamical environmental systems models in general.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): Natasha Carmi, Mey Alsayegh, Maysoon Zoubi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Until now, limited attention has been afforded to the role of, and challenges faced by, women involved in water diplomacy. In addition to research being at an early stage, it is mainly focused on addressing the challenges imposed by gender inequality. Thus very few applicable policy recommendations have emerged in this field to date.〈/p〉 〈p〉This paper will explore and identify current challenges that face the women interested in attaining high level positions in water diplomacy, in three Arab countries in which hydropolitics prevails, including Jordan, Lebanon and the State of Palestine. Female experts working on water-related issues were surveyed and interviewed to ascertain key qualitative issues, perceptions and various challenges. The focus of the paper was to identify the additional skills to be developed and acquired, for these women to better qualify as water diplomats both nationally and globally. In addition, the paper explores how to better equip women as leaders in the attainment of the Sustainable Development Goals, especially Goal 5 on Gender Equality and Goal 6 on Clean Water and Sanitation, in their national water sectors. The results provide a basic and initial mapping of current challenges and makes recommendations that would assist in the empowerment of those women in water diplomacy decision making positions in the regions investigated specifically, as well as globally.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): W.Q. Jiang, G.Q. Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A general analytical procedure based on phase averaged formulation is presented in this work to investigate environmental dispersion in layered wetland. Based on concentration moments, Chatwin’s long-time asymptotic technique is applied to describe both the longitudinal distribution of the depth-averaged concentration and the two-dimensional concentration field, including their longitudinal non-Gaussian effects of skewness and Kurtosis. Three wetlands of equal depth-averaged porosity but with different number of layers are studied to illustrate the impact of layered structure on solute transport. The layered structure of wetlands leads to great changes in velocity profiles and evolution of environmental dispersivity, skewness and kurtosis of depth-averaged concentration distribution. In each layer, vertical distribution of concentration is highly nonuniform in the initial stage of transport. Layers with different porosity result in essential difference between layer-averaged concentrations, of which all tend to be normally distributed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 569〈/p〉 〈p〉Author(s): Guofeng Zhu, Huiwen Guo, Dahe Qin, Hanxiong Pan, Yu Zhang, Wenxiong Jia, Xinggang Ma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The hydrogen and oxygen isotope composition of precipitation and water vapor are useful tracers in the water cycle. The water balance of inland river basins located in the monsoon marginal zone are difficult to determine, because little is known about the contribution of various vapor involved. Based on the three-component isotopic mixing model, the monthly precipitation, surface water and plant water isotope data of the seven sampling stations from April to October 2017 were used to assess the vapor contribution to precipitation in the Shiyang River basin.〈/p〉 〈p〉The average contribution of plant transpiration, land surface evaporation and advected vapor to precipitation accounted for 11%, 6% and 83% in the Mountain regions, for 21%, 7% and 72% in the Oasis regions, and for 10%, 5% and 85% in the Desert regions, respectively. The contribution of plant transpiration and surface evaporation vapor was similar in time variation, and the maximum value appeared in July. The average plant transpiration vapor contribution at each station was always greater than the surface evaporation vapor. Different landscape and special underlying surfaces are important factors influencing the difference in water vapor contribution. The average surface evaporation water vapor contribution of the Xiying (M1) station is the largest in the study area, with a contribution fraction of 9%. The contribution of Wuwei oasis recycled moisture can reach 30%, the plant transpiration vapor accounted for 73%.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Tirthankar Roy, Juan B. Valdés, Bradfield Lyon, Eleonora M.C. Demaria, Aleix Serrat-Capdevila, Hoshin V. Gupta, Rodrigo Valdés-Pineda, Matej Durcik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We assess the impacts of a range of short-term climate change scenarios (2020–2050) on the hydrology of the Mara River Basin in East Africa using a new high-resolution (0.25°) daily climate dataset. The scenarios combine natural climate variability, as captured by a vector autoregressive (VAR) model, with a range of climate trends calculated from 31 models in the Coupled Model Intercomparison Project Phase 5 (CMIP5). The methodology translates these climate scenarios into plausible daily sequences of climate variables utilizing the Agricultural Modern-Era Retrospective Analysis for Research and Applications (AgMERRA) dataset. The new dataset (VARAG) has several advantages over traditional general circulation model outputs, such as, the statistical representation of short-term natural climate variability, availability at a daily time scale and high spatial resolution, not requiring additional downscaling, and the use of the AgMERRA data which is bias-corrected extensively. To assess the associated impacts on basin hydrology, the semi-distributed Variable Infiltration Capacity (VIC) land-surface model is forced with the climate scenarios, after being calibrated for the study area using the fine-resolution (0.05°) merged satellite and in-situ observation-based dataset, Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS). The climate data are further bias-corrected by applying a non-parametric quantile mapping scheme, where the cumulative distribution functions are approximated using kernel densities. Three different wetness scenarios (〈em〉dry〈/em〉, 〈em〉average〈/em〉, and 〈em〉wet〈/em〉) are analyzed to see the potential short-term changes in the basin. We find that the precipitation bias correction is more in effect in the mountainous sub-basins, one of which also shows the maximum difference between the wet and dry scenario streamflows. Precipitation, evapotranspiration, and soil moisture show increasing trends mostly during the primary rainy season, while no trend is found in the corresponding streamflows. The annual values of these variables also do not change much in the coming three decades. The methodology implemented in this study provides a reliable range of possibilities which can greatly benefit risk analysis and infrastructure designing, and shows potential to be applied to other basins.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): James L. McCallum, Shawan Dogramaci, Peter G. Cook, Eddie Banks, Roland Purtschert, Michelle Irvine, Craig T. Simmons, Lawrence Burk〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon-14 (〈sup〉14〈/sup〉C) has been measured in groundwater for over half a century and remains a widely used tool for understanding groundwater flow systems. Ultimately, the usefulness of 〈sup〉14〈/sup〉C as a groundwater tracer relies on the ability to distinguish between changes in concentration due to various chemical/physical processes (e.g. chemical reactions with solid carbonate material, conditions at the water table), and changes due to ageing along flow paths, the latter being most informative of groundwater flow conditions. To this end, a number of correction methodologies have been developed to account for chemical modifications in groundwater systems. In this paper, we implement two different single sample correction models, one for closed and one for open system carbonate dissolution in conjunction with a Markov chain Monte Carlo (MCMC) approach at two sites; the sedimentary Port Willunga Formation Aquifer in South Australia and a fractured rock aquifer in the Hamersley Basin, northwest Australia. For comparison, we include argon-39 (〈sup〉39〈/sup〉Ar) data taken from some of the wells sampled and use a mixing envelope constraint in the MCMC procedure. We found that considering all of the errors associated with 〈sup〉14〈/sup〉C correction resulted in a distribution of values to consider for groundwater dating procedures. When accounting for all parameters associated with single sample correction techniques, the associated error was 10 times greater than the analytical errors. Additionally, inclusion of the 〈sup〉39〈/sup〉Ar data produced mixed results, with little improvement observed in the Port Willunga Aquifer (closed system correction), and a significant improvement observed at the Hamersley site (open system). This is most likely due to the mixing caused by long screens and the sensitivity of the open system correction model. Our results highlight the importance of considering all sources of error in groundwater dating studies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Andrew Ogilvie, Gilles Belaud, Sylvain Massuel, Mark Mulligan, Patrick Le Goulven, Pierre-Olivier Malaterre, Roger Calvez〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Small reservoirs represent a critical water supply to millions of farmers across semi-arid regions, but their hydrological modelling suffers from data scarcity and highly variable and localised rainfall intensities. Increased availability of satellite imagery provide substantial opportunities but the monitoring of surface water resources is constrained by the small size and rapid flood declines in small reservoirs. To overcome remote sensing and hydrological modelling difficulties, the benefits of combining field data, numerical modelling and satellite observations to monitor small reservoirs were investigated. Building on substantial field data, coupled daily rainfall-runoff and water balance models were developed for 7 small reservoirs (1–10 ha) in semi arid Tunisia over 1999–2014. Surface water observations from MNDWI classifications on 546 Landsat TM, ETM+ and OLI sensors were used to update model outputs through an Ensemble (n = 100) Kalman Filter over the 15 year period. The Ensemble Kalman Filter, providing near-real time corrections, reduced runoff errors by modulating incorrectly modelled rainfall events, while compensating for Landsat’s limited temporal resolution and correcting classification outliers. Validated against long term hydrometric field data, daily volume root mean square errors (RMSE) decreased by 54% to 31 200 m〈sup〉3〈/sup〉 across 7 lakes compared to the initial model forecast. The method reproduced the amplitude and timing of major floods and their decline phases, providing a valuable approach to improve hydrological monitoring (NSE increase from 0.64 up to 0.94) of flood dynamics in small water bodies. In the smallest and data-scarce lakes, higher temporal and spatial resolution time series are essential to improve monitoring accuracy.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Marcus Suassuna Santos, Luis Mediero, Carlos Henrique Ribeiro Lima, Leonardo Zandonadi Moura〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The identification of storm tracks that generate the annual maximum floods and the quantification of their air-moisture content is proposed to understand better the atmospheric generation processes of floods in Spain, as well as their decreasing trends identified previously. In this work, the role of the atmospheric component on hydrological changes on Spain by using storm track data generated by the hybrid single particle Lagrangian integrated trajectory model (HYSPLIT) is examined. Storm tracks associated with annual maximum flood series from 14 streamflow gauges located across Spain are obtained by using NCEP/NCAR Reanalysis data. They are classified into five clusters through use of the K-means algorithm. It was also shown that the use of five clusters was able to reproduce the five major types of storms identified in Spain reported in the literature. The posterior grouping of the five associated storm types into two bigger groups (Oceanic and Continental storms), led to a coherent seasonal and spatial behaviour of hydrological regimes. For some gauges, it was observed that distinct flood statistics, such as mean and variance, differ significantly as a result of atmospherically distinct generation processes, suggesting that local annual maximum flood series may be non-homogeneous as a result of contrasting atmospheric generation processes. By means of logistic regression, it is estimated that the probability of occurrence of Oceanic storms reduced significantly in the Spanish Atlantic region along the studied period. Furthermore, the existence of low-frequency cycles introduces significant variation in the occurrence of storm types in the country, with them being much more frequent during the period 1975–1979, while Oceanic storms were more frequent during the 1983–1987 and 1996–1999 periods. Those storms classified as Continental are observed in 59.3% of the studied cases, while those termed Oceanic in 40.7%. Continental storms also contribute with more moisture in the studied cases, that is to say, 63.1% of total moisture content, while Oceanic storms contributed with 36.9%.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Lingling Bin, Kui Xu, Xinyi Xu, Jijian Lian, Chao Ma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Haihe River Basin has become a watershed that suffers from intensive interference from human activities, as landscape patterns and runoff processes have significantly changed in recent decades. Investigating the effect of landscape patterns on surface runoff is helpful for establishing the synergistic evolution relationship between the landscape and the hydrological cycle, providing a theoretical basis and effective way for the future management of water resources. In this study, a landscape metrics approach is used to describe the spatial patterns of landscapes, measure changes in landscape patterns, and relate spatial patterns to surface runoff processes of water resources at a watershed scale. Given that commonly used landscape metrics not considering undulating terrain characteristics, soil properties and landcover conditions, which have significant effects on the surface runoff, a Runoff Landscape Index (RLI) is developed to evaluate the effect of watershed landscape factors on surface runoff. Factors relating to landcover, soil and topography are analyzed, weighed, and integrated during the indicator development. Then, correlation between landscape indicators (RLI and commonly used indicators) and surface runoff is examined. The results show a significant positive correlation between RLI and surface runoff, and the average correlation coefficient is 0.831, much greater than the correlation coefficients for commonly used landscape indices. With potential applications for remote sensing and GIS technology, RLI could be used to efficiently predict annual runoff in ungauged basins even in future land cover scenarios and possibly provide a new perspective for water resource management at the river basin scale.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Anna Menció, Dani Boix〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mediterranean rivers are affected by natural disturbances and human pressures, which may alter their hydrology, water quality and habitat structure. In this study an analysis of macroinvertebrates community structure has been used to determine how distinct human pressures, such as point and non-point sources of pollution, together with groundwater withdrawal, may affect these ecosystems. A total of 4 sampling campaigns were conducted in the middle reach of the Onyar River (NE Spain), which was affected by agricultural and urban uses. Stream discharge and physicochemical parameters were measured 〈em〉in situ〈/em〉, and water samples and macroinvertebrates assemblages were taken and properly preserved for subsequent analysis and identification. Variation partitioning showed that macroinvertebrate community structure was particularly dependent on hydrochemical characteristics, but also on hydrological variations. In addition, results indicated that groundwater withdrawal altered stream hydrology, and the main reach of the Onyar River became intermittent and even completely dry in downstream positions. This reduction on stream discharge caused changes in habitat characteristics, as well as in the proportion of wastewater. Some wastewater dilution occurred, linked to groundwater with high nitrate concentrations inputs to the stream, and even though the macroinvertebrate community recovered its quality in some sampling campaigns, it presented a different structure than in sampling points not affected by any of these pressures. Therefore, the approach here used to analyze the hydrological effects on macroinvertebrate communities allowed us to determine their influence on hydrochemical and habitat characteristics.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418307340-ga1.jpg" width="313" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Carlos H.R. Lima, Hyun-Han Kwon, Yong-Tak Kim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Future changes in rainfall patterns induced by climate changes will affect society and ecosystems, and quantifying these changes is of utmost importance for the management of hydroclimate risk. In particular, the estimation of intensity-duration-frequency (IDF) curves for rainfall data is a routine procedure in urban hydrology and hydraulic studies and should be revisited to reflect future changes in rainfall variability. In this work, we propose a novel methodology based on the scaling-invariant property of rainfall duration versus intensity to estimate parameters of a generalized extreme value (GEV) distribution at sub-daily scales. A Bayesian inference framework is developed so that uncertainties are reduced and can be easily propagated to IDF curves. The proposed model can be employed to: (i) improve local (at-site) GEV estimates for sites with limited rainfall records; (ii) estimate GEV parameters at sub-daily scales and construct IDF curves for sites where only daily rainfall records are available (partially gauged sites); (iii) construct regional IDF curves for homogeneous hydrologic regions; and (iv) update local and regional IDF curves from simulations of future daily rainfall. The model is tested using historical rainfall data from 18 gauges located in the Han River Watershed in South Korea, and projected climate change scenarios RCP 6 and RCP 8.5 from the Met Office Hadley Centre HadGEM2-AO model. When considering historical data, the results show that the model satisfactorily estimate IDF curves for both gauged and partially gauged sites. In future scenarios, the model reveals a substantial increase in rainfall events of rare intensity (large return periods), mostly due to changes in the rainfall variability rather than changes in the average rainfall. Particularly, for a 100-year return period event, we expect an increase of about 23% in scenario RCP 6 and about 30% under scenario RCP 8.5 when projected using regional IDF curves. To the best of our knowledge, this is the first statistical approach in the literature to assess future changes in regional IDF curves, which in our opinion is more suitable than evaluating local estimates only.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Qifeng Gao, Guojian He, Hongwei Fang, Sen Bai, Lei Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉After the impoundment of Three Gorges Reservoir, algal blooms frequently occurred in the tributaries of the reservoir, which has posed a great challenge for the local aquatic environment and ecology. To investigate the main causes and key factors of the algal blooms, the Environmental Fluid Dynamics Code (EFDC) model is applied to the simulation of the three-dimensional hydrodynamics and water quality in the Yangtze River and Xiangxi Bay, and the concept of water age is adopted to quantitatively analyze the effects of hydrodynamics on the water quality by linking water age and phytoplankton levels, which has seldom been explored in previous studies. The model results show good agreement with the field data, and the simulation reproduces the thermal stratification and density current in Xiangxi Bay. The results show that Xiangxi Bay exhibits quite complicated hydrodynamic characteristics, and could be divided into different zones according to the transport process. In the upper reach, the water quality is mainly affected by the upstream inflows, while it is mainly affected by the intrusion flow from the mainstream near the river mouth. Water age and water temperature are found to be the key factors influencing the algal blooms in Xiangxi Bay. Besides, a significant positive correlation has been found between the chlorophyll 〈em〉a〈/em〉 (chl-〈em〉a〈/em〉) concentration in the surface layer and the water age of the dominant water source. This conclusion can be adopted to interpret the longitudinal distribution of chl-〈em〉a〈/em〉 concentration and to explain why Xiangxi Bay is susceptible to algal blooms. The correlation between water age and chl-〈em〉a〈/em〉 concentration is further used to evaluate the effectiveness of water level fluctuation in preventing algal blooms. The analyses and findings in this study could help to better understand the complicated hydrodynamic and water quality processes in Xiangxi Bay following the impoundment, and provide insights into ecological and environmental management of Three Gorges Reservoir.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418307194-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Christopher D. Shultz, Timothy K. Gates, Ryan T. Bailey〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A calibrated fate and reactive transport model is applied to evaluate alternative water and land best management practices (BMPs) in Colorado’s intensively irrigated Arkansas River Valley to attenuate nonpoint source pollution and more closely meet regulatory standards for selenium (Se) and nitrogen (N) in groundwater and streams. Reduced irrigation (RI), lease fallowing (LF), canal sealing to reduce seepage (CS), reduced fertilizer application (RF), and enhanced riparian buffers (ERB) are explored as stand-alone BMPs, and in combination, at basic to more aggressive levels of implementation. The distributed-parameter model, which couples MODFLOW-SFR with RT3D-OTIS, predicts impacts that vary significantly over a region encompassing about 500 km〈sup〉2〈/sup〉 and across time. Results suggest that, over the course of several decades, average Se and nitrate-nitrogen (NO〈sub〉3〈/sub〉-N) groundwater concentrations within the region could be lowered by as much as 23% and 40%, respectively, using combined BMPs. Average Se concentration in the river could be decreased by up to 56% with combined BMPs, and NO〈sub〉3〈/sub〉-N concentrations by up to 32% by using ERB. The CS-RF-ERB combination type may be the most promising for simultaneously lowering both Se and NO〈sub〉3〈/sub〉-N concentrations. To insure compliance with Colorado water rights and the Arkansas River Compact with Kansas, measures must be taken to compensate for altered return flow patterns that will be a consequence of BMP implementation. Results also point to the need to consider the targeting of BMPs to specific locations within the region to maximize their effectiveness and efficiency.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Catherine Wilcox, Théo Vischel, Gérémy Panthou, Ansoumana Bodian, Juliette Blanchet, Luc Descroix, Guillaume Quantin, Claire Cassé, Bachir Tanimoun, Soungalo Kone〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In recent years, West Africa has witnessed an increasing number of damaging floods that raise the question of a possible intensification of the hydrological hazards in the region. In this study, the evolution of extreme floods is analyzed over the period 1950–2015 for seven tributaries in the Sudano-Guinean part of the Senegal River basin and four data sets in the Sahelian part of the Niger River basin. Non-stationary Generalized Extreme Value (NS-GEV) distributions including twelve models with time-dependent parameters plus a stationary GEV are applied to annual maxima of daily discharge (AMAX) series. An original methodology is proposed for comparing GEV models and selecting the best for use. The stationary GEV is rejected for all stations, demonstrating the significant non-stationarity of extreme discharge values in West Africa over the past six decades. The model of best fit most commonly selected is a double-linear model for the central tendency parameter (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi〉μ〈/mi〉〈/mrow〉〈/math〉), with the dispersion parameter (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈mi〉σ〈/mi〉〈/mrow〉〈/math〉) modeled as either stationary, linear, or a double-linear. Change points in double-linear models are relatively consistent for the Senegal basin, with stations switching from a decreasing streamflow trend to an increasing streamflow trend in the early 1980s. In the Niger basin the trend in 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi〉μ〈/mi〉〈/mrow〉〈/math〉 is generally positive since the 1970s with an increase in slope after the change point, but the change point location is less consistent. The recent increasing trends in extreme discharges are reflected in an especially marked increase in return level magnitudes since the 1980s in the studied Sahelian rivers. The rate of the increase indicated by the study results raises urgent considerations for stakeholders and engineers who are in charge of river basin management and hydraulic works sizing.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Shijie Jiang, Yi Zheng, Vladan Babovic, Yong Tian, Feng Han〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study develops a novel approach to data-driven hydrological modeling. The approach adopts the feature representation technique in computer vision to effectively exploit spatial information contained in time-variant input data fields and seamlessly fuse multisource information via machine learning. The new approach overcomes a major limitation of existing approaches in which the spatial heterogeneity of input variables cannot be sufficiently accounted for. The approach is applied to predict the streamflow in a watershed on the northern margin of the Qinghai-Tibetan Plateau, and its performance is compared with various data-driven and process-based models. The major findings are as follows. First, the new approach represents a general framework for the fusion of multisource spatiotemporal data for hydrological modeling and demonstrates great potential to incorporate fast-growing environmental big data. Second, the new approach demonstrates satisfactory short-term forecasting, long-term simulation, and transfer learning performances and is promising for addressing predictions in ungauged basins. Third, the predictors, including precipitation, temperature, leaf area index, and historical streamflow, play markedly distinct roles in modeling streamflow with the novel approach. Finally, topographic information is not a necessary model input in the proposed approach because spatial patterns can be well embodied by other inputs (e.g., temperature) that have high similarities with topography. This study represents the first attempt to bring computer vision into data-driven hydrological modeling and may inspire future studies in this promising direction.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): A. Musolff, J.H. Fleckenstein, M. Opitz, O. Büttner, R. Kumar, J. Tittel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Elevated concentration and high variance of dissolved organic carbon (DOC) in surface waters are a challenge for the production of drinking water. Past studies have indicated a dominant role of wetlands in DOC mobilization, but have mainly been focused on boreal and oceanic catchments. Here we analyze the observational DOC time series from 89 temperate humid catchments which drain into German drinking water reservoirs. We characterize the DOC concentration median and variability and utilize partial least squares regression in order to quantify the relation to catchment characteristics such as land use, climate, and topography. We found that the long-term median DOC concentration in the catchment is well predicted by the 90th percentile of the distribution of the topographic wetness index (0.9P TWI) over the entire catchment area. The 0.9P TWI can be directly connected to the abundance of riparian wetlands in the catchments. DOC concentration variability (represented as the ratio of the interquartile range and the median concentrations) was also found to be well predictable. Concentration variability was highest in cold and wet catchments with a high 0.9P TWI. Here we also found stronger correlations between DOC concentrations and discharge, with positive concentration-discharge patterns. Catchments with elevated DOC-concentration variance also exhibited the most severe long-term increases in concentrations. Our results thus indicate that, in temperate climates, riparian wetlands can be the dominant source zones of DOC and control the hydrological mobilization and potentially also the spatial difference in long-term concentration trends observed in surface waters. We conclude that the dominance of topography and climatic conditions in controlling spatio-temporal patterns in DOC concentrations leads to very limited management options.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Ali Danandeh Mehr, Vahid Nourani, Ercan Kahya, Bahrudin Hrnjica, Ahmed M.A. Sattar, Zaher Mundher Yaseen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The state-of-the-art genetic programming (GP) method is an evolutionary algorithm for automatic generation of computer programs. In recent decades, GP has been frequently applied on various kind of engineering problems and undergone speedy advancements. A number of studies have demonstrated the advantage of GP to solve many practical problems associated with water resources engineering (WRE). GP has a unique feature of introducing explicit models for nonlinear processes in the WRE, which can provide new insight into the understanding of the process. Considering continuous growth of GP and its importance to both water industry and academia, this paper presents a comprehensive review on the recent progress and applications of GP in the WRE fields. Our review commences with brief explanations on the fundamentals of classic GP and its advanced variants (including multigene GP, linear GP, gene expression programming, and grammar-based GP), which have been proven to be useful and frequently used in the WRE. The representative papers having wide range of applications are clustered in three domains of hydrological, hydraulic, and hydroclimatological studies, and outlined or discussed at each domain. Finally, this paper was concluded with discussions of the optimum selection of GP parameters and likely future research directions in the WRE are suggested.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Xinjun Tu, Haiou Wu, Vijay P. Singh, Xiaohong Chen, Kairong Lin, Yuting Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Socioeconomic drought in association with minimum instream flow against the backdrop of local water supply was investigated. An integrated procedure for design combinations of drought properties, such as duration, severity, and peak, involving the truncation of drought events, the goodness-of-fit of joint and marginal distributions of drought properties, the determination of design combinations of these properties for a given Kendall return period, and the evaluation of uncertainty of the combinations, was developed. In multivariate design of socioeconomic droughts in a case study, univariate, bivariate and trivariate design values of drought properties and their alterations due to the regulation of water reservoirs were computed. Results showed that any two properties of drought exhibited a high positive dependence. For a given bivariate return period, the pairs of cumulative frequencies of drought properties formed a symmetric curve for truncated samples and a symmetric curving-belt for large quantities of simulated samples. For a given trivariate return period, the pairs of cumulative frequencies of duration and peak showed a symmetry, but the pairs of duration and severity or severity and peak were remarkably scattered on the side of severity and comparatively concentrated on the side of duration or peak. For the confidence interval of probability of 0.95, the range of trivariate design values was larger than that of bivariate design. The differences between drought design values of univariate, bivariate, and trivariate designs were small, which resulted from high correlations of drought properties, the use of Kendall frequency, and approximate identical cumulative frequencies in design combinations. The decrease of socioeconomic drought properties under the regulation of water reservoirs was significant, but the drought spell, total volume, and monthly maximum of water deficit for a 5-year return period still accounted for 3.06–3.27 months, 0.426–0.470 billion m〈sup〉3〈/sup〉, and 0.211–0.217 billion m〈sup〉3〈/sup〉, respectively, provided that the local water supply was met.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Long Sun, Lei Yang, Liding Chen, Fangkai Zhao, Shoujuan Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydraulic redistribution (HR) in sites with shallow soils and its response to random droughts during the summer rainy season in humid areas remains poorly understood. We investigated the soil moisture dynamics, HR and water buffer of shallow soils by monitoring the soil moisture content at multiple depths during a random drought event in the summer rainy season, in typical forestland and orchard in a subtropical area. Soil moisture sensors were installed at depths of 5, 10, 15, 20 and 30 cm at three sites (forest, peach1, and peach2). The total and net daily water use and water buffer capacity of the root zone were defined and calculated. During the short-term drought, the HR of soil moisture occurred at all sites, suggesting that it could be an important process in both forest and orchard land in response to short-term drought. HR occurred at both daily and multiple-day timescales in the shallow soils. The net daily water use had less difference between the sites than the total daily water use. Principal component analysis of the total and net daily water use showed only evident clustering characteristics for the total daily water use, indicating an important plant-soil interaction effect. The depth-averaged magnitude of daily HR varied from 0.385 mm (0.0077 m〈sup〉3〈/sup〉 m〈sup〉−3〈/sup〉) at the forest site to 0.725 mm (0.0145 m〈sup〉3〈/sup〉 m〈sup〉−3〈/sup〉) at the peach1 site. The redistributed water replenished over 75% of the water depleted from the shallow soil. In particular, soil moisture was better retained in 15–20 cm root zone than in other soil layers. Furthermore, the water buffer capacity of the forest site was not higher than those of the two peach sites (where land use converted from forest), indicating that land use conversion does not necessarily weaken soil water retention. The study results highlighted that HR has a significant influence on water recharge and water retention in humid area, thus benefiting plant drought tolerance and total water utilization. This study provides more insights to evaluate HR’s effect on water retention and enhance our understanding of HR in shallow soils during random droughts in the summer rainy season in humid areas.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Sami Ghordoyee Milan, Abbas Roozbahani, Mohammad Ebrahim Banihabib〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sustainable water resources management in most river basins needs appropriate techniques to implement the conjunctive use of surface and groundwater resources with consideration of uncertainties. In this study, first a linear fuzzy optimization model was used to find the optimal surface and groundwater withdrawal. Then, by using the results of this model, a Fuzzy Inference System (FIS) was developed to determine the groundwater withdrawal, automatically. The capability of this approach is studied in the Astaneh-Kouchesfahan Plain in north of Iran. To do this, the groundwater of this Plain was simulated using MODFLOW code. Then, two fuzzy optimization methods were developed to minimize the water shortage. Results showed that the average water shortage was equal to 215 and 138 MCM according to current water withdrawal and the best solution for the fuzzy optimization model which was 22.0% and 14.6% of the water demand, respectively. The results of the optimization model were used to predict the optimal water withdrawal of the aquifer using the FIS, considering the predictor variables. These variables were applied to the developed FIS model under different scenarios in order to determine the best scenario with the highest prediction performance for water withdrawal from the aquifer. The evaluation criteria were coefficient of determination, normalized root mean square error, and the mean absolute error which were equal to 0.94, 0.26 MCM and 3.8 MCM, respectively for the best scenarios. These scenarios were able to predict the optimal amount of groundwater withdrawal and can replace the numerical optimization methods.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Anamika Barua〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The Yarlung Zangbo-Brahmaputra – Jamuna river basin 〈em〉(further referred to as Brahmaputra River Basin)〈/em〉 is one of the most important river systems in South Asia. It originates on the Tibetan Plateau and links Bangladesh, Bhutan, China, and India. Despite being an important river system of South Asia, with an immense potential for regional development, very little progress has been made so far at regional level to manage this transboundary river. Apart from stereotypical upstream-downstream syndromes, a lack of trust, an atmosphere of hostility, and an asymmetric information and power situation as also the absence of regional principles or frameworks make transboundary interaction between the Brahmaputra riparian countries complex and challenging. The lack of information and knowledge regarding the river itself makes decision-making further complicated. Negotiation for a basin-wide treaty on cooperation in the absence of trust is a non-starter for the Brahmaputra basin, for it may result in asymmetric cooperation, opening up ground for future conflicts. To avoid such asymmetric cooperation, information-rich, multilateral informal dialogues need to take place to develop an accepted definition of cooperation, which meets the needs of all riparian states.〈/p〉 〈p〉The article provides an outline of the current issues in the Brahmaputra river basin and illustrates the need for multitrack and multi-stakeholder dialogues in the Brahmaputra region. The paper is inspired by the ‘Brahmaputra Dialogue’ project initiated in 2013, that demonstrates that water diplomacy has to be an inclusive, open, and transparent process involving multiple actors, because such interaction facilitates sustainable water cooperation, not only between riparian countries but also between riparian communities.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Qingwen Zhang, Ningbo Cui, Yu Feng, Daozhi Gong, Xiaotao Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Reference evapotranspiration (〈em〉ET〈/em〉〈sub〉0〈/sub〉) is an important parameter for climatological and hydrological studies, as well as for agricultural water resources management. In this study, 7 temperature-based solar radiation models were adopted to improve the Makkink model for 〈em〉ET〈/em〉〈sub〉0〈/sub〉 estimation in Northwest China. The temperature-based models only require air temperature as input data, which can be easily monitored in most areas around the world. The applicability of the improved Makkink models (M1-M7), the original Makkink (MK) model, the Jensen-Haise (JH) model as well as the Irmak (IK) model were evaluated on different time scales using meteorological data obtained from 12 weather stations in Northwest China. The results showed that the 7 improved Makkink (MK〈sub〉i〈/sub〉) models (〈em〉R〈/em〉〈sup〉2〈/sup〉 ranged 0.71–0.86) were more accurate than the 3 physical models (〈em〉R〈/em〉〈sup〉2〈/sup〉 ranged 0.64–0.76) for daily 〈em〉ET〈/em〉〈sub〉0〈/sub〉 estimation at the 4 sub-zones of Northwest China, and the M4, M5, M6 and M7 models were superior to the other models. The M5 model had the best estimation accuracy for daily 〈em〉ET〈/em〉〈sub〉0〈/sub〉 on daily scale, followed by M7 and M6, with the 〈em〉R〈/em〉〈sup〉2〈/sup〉 median of 0.83, 0.83 and 0.82, the RMSE median of 0.86, 0.88 and 0.89 mm/d, and the GPI median of 1.03, 0.90 and 0.87, respectively. On monthly scale, the 7 MK〈sub〉i〈/sub〉 models (with relative error almost less than 20%) were also better than the 3 physical models (with relative error usually more than 20%) at the 4 sub-zones. The M5 model also showed the best performance for monthly average daily 〈em〉ET〈/em〉〈sub〉0〈/sub〉 estimation, followed by M7 and M6, with the 〈em〉R〈/em〉〈sup〉2〈/sup〉 median of 1.00, 1.00 and 1.00, the RMSE median of 0.13, 0.16 and 0.19 mm/d, and the GPI median of 0.25, 0.05 and 0.02, respectively. Overall, the estimation accuracy of the Makkink model was much improved by using the temperature-based solar radiation models, and in Northwest China, M5 model which only requires temperature and relative humidity as input data is highly recommended to estimate 〈em〉ET〈/em〉〈sub〉0〈/sub〉 on both daily and monthly scales.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Xueyuan Kang, Xiaoqing Shi, Yaping Deng, André Revil, Hongxia Xu, Jichun Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Characterization of dense non-aqueous phase liquid (DNAPL) distribution is important to facilitate the decision of remediation strategies. However, it is still a great challenge to characterize DNAPL source zone architecture with high resolution due to subsurface heterogeneity and relatively sparse data from traditional hydrogeological investigations. To overcome difficulties from such sparse data, electrical resistivity tomography (ERT) is introduced to locate DNAPL using time-lapse cross-borehole measurements. Due to the significant impact of geological heterogeneity on DNAPL source zone architecture, a data assimilation framework based on the coupled multiphase fluids-ERT model is developed to jointly invert DNAPL saturation and the permeability field using time-lapse ERT data. To validate the efficiency and performance of this framework, synthetic and laboratory experiments are both performed to monitor DNAPL migration and distribution in 3D heterogeneous sandbox with cross-borehole ERT. Result shows that time-lapse ERT and direct inversion can map the evolution of the DNAPL plume but loses details regarding the plume morphology due to the over-smoothing caused by geophysical inversion using an isotropic and homogeneous roughness-based regularization procedure. By contrast, the coupled inversion is successful to characterize both the permeability field and the evolution of the DNAPL plume with a higher resolution. This is because the coupled inversion is able to directly translate raw geophysical data into hydrologic meaningful information and therefore avoid artifacts caused by direct geophysical inversion.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Roderick W. Lammers, Brian P. Bledsoe〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Excessive river erosion and sedimentation threatens critical infrastructure, degrades aquatic habitat, and impairs water quality. Tools for predicting the magnitude of erosion, sedimentation, and channel evolution processes are needed for effective mitigation and management. We present a new numerical model that simulates coupled river bed and bank erosion at the watershed scale. The model uses modified versions of Bagnold’s sediment transport equation to simulate bed erosion and aggradation, as well as a simplified Bank Stability and Toe Erosion Model (BSTEM) to simulate bank erosion processes. The model is mechanistic and intermediate complexity, accounting for the dominant channel evolution processes while limiting data requirements. We apply the model to a generic test case of channel network response following a disturbance and the results match physical understanding of channel evolution. The model was also tested on two field data sets: below Parker Dam on the lower Colorado River and the North Fork Toutle River (NFTR) which responded dramatically to the 1980 eruption of Mount St. Helens. It accurately predicts observed channel incision and bed material coarsening on the Colorado River, as well as observations for the upstream 18 km of the NFTR watershed. The model does not include algorithms for extensive lateral migration and avulsions and therefore did not perform well in the lower NFTR where the channel migrated across a wide valley bottom. REM is parsimonious and useful for simulating network scale channel change in single thread systems responding to disturbance.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418307303-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 9 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology〈/p〉 〈p〉Author(s): Wanqiu Xing, Weiguang Wang, Quanxi Shao, Bin Yong, Catherine Liu, Xiaozhou Feng, Qing Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The estimates of actual evapotranspiration (〈em〉E〈/em〉) across basins and/or regions are still facing some difficulties because of the complex interactions amongst the components of the land-plant-atmosphere system, even though the basic physical mechanism of 〈em〉E〈/em〉 is well understood. Presenting as a nonlinear relationship constrained by physical limits, the Budyko framework serves as a powerful tool used to estimate the averaged 〈em〉E〈/em〉 at long-term scale. Given the ability of Gravity Recovery And Climate Experiment (GRACE) in effectively simulating the terrestrial water storage change (Δ〈em〉TWS〈/em〉) at monthly scale, a model to estimate 〈em〉E〈/em〉 was developed based on the Budyko framework with mean monthly parameter of multi-years, and was applied to the estimation of 〈em〉E〈/em〉 for the 24 selected catchments in different climatic regions across China. Results indicate that for the majority of 24 catchments, the positive or negative trends in precipitation (〈em〉P〈/em〉), potential evapotranspiration (〈em〉E〈/em〉〈sub〉0〈/sub〉), runoff (〈em〉R〈/em〉) and Δ〈em〉TWS〈/em〉 were not statistically significant during 2003–2013 at both annual and monthly scales, but the Δ〈em〉TWS〈/em〉 occupied a large proportion in the partitioning of 〈em〉P〈/em〉 into 〈em〉R〈/em〉 and 〈em〉E〈/em〉 at monthly scale. The monthly Budyko parameter showed large variation within the year and also across these 24 catchments. The Budyko-modeled monthly 〈em〉E〈/em〉 (Budyko-E) represented the GRACE-derived ones (GRACE-E) across these catchments well with both modeled 〈em〉E〈/em〉 volumes and hydrograph shapes which were also consistent with GRACE-E series except some underestimation for peak 〈em〉E〈/em〉. Overall, the Budyko-E represented GRACE-E in the arid and semi-arid catchments comparatively better than it in the humid and semi-humid catchments due to the larger proportion of Δ〈em〉TWS〈/em〉 in the 〈em〉P〈/em〉 partition. Among all the 24 selected catchments, the monthly Budyko-type 〈em〉E〈/em〉 model represented the GRACE-E across Shixiali catchment (located in the Hai River basin) best, with the correlation coefficient (〈em〉r〈/em〉), Nash-Sutcliffe coefficient (〈em〉NSCE〈/em〉) and relative error (〈em〉RE〈/em〉) between GRACE-E and simulated results being 0.996, 0.988, −0.033 in calibration and 0.994, 0.951, −0.111 in validation, respectively. Furthermore, using GRACE-E as the benchmark values, the Budyko-E outperformed four other global 〈em〉E〈/em〉 products from the newly published Global Land Data Assimilation System with Noah Land Surface Model-2 (GLDAS_E), MODIS (MODIS_E), Japanese 25-year reanalysis product (JRA_E), and Zhang’s method (Zhang_E). GLDAS_E was the best of four global 〈em〉E〈/em〉 products at reproducing monthly variations, with relatively high 〈em〉r〈/em〉 and 〈em〉NSCE〈/em〉 values, small 〈em〉RE〈/em〉. While MODIS_E showed the poorest performance in reproducing the inter-annual 〈em〉E〈/em〉 variations of these catchments, which was reflected by low 〈em〉r〈/em〉 and 〈em〉NSCE〈/em〉 values. This extended Budyko-E model can apply in other similar climatic regions and also may provide skill in evaluating the water resources since the preferable accuracy of 〈em〉E〈/em〉 estimate.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418307753-ga1.jpg" width="395" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Weiming Xie, Qing He, Xianye Wang, Leicheng Guo, Keqi Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Intertidal environments, including bare mudflats, tidal creeks, and vegetated salt marshes, are of significant physical and ecological importance in estuaries. Their morphodynamics are closely linked by mudflats and creek networks. Understanding water motion and sediment transport in mudflats and tidal creeks is fundamental to understand intertidal morphodynamics in intertidal environments. To explore dynamic interactions between tidal creeks and mudflats, we conducted field campaigns monitoring water depths, tidal currents, waves, suspended sediments, and bed-level changes at sites in both mudflats and tidal creeks in the Eastern Chongming tidal wetland in the Yangtze Delta for a full spring-neap tidal cycle. We saw that under fair weather conditions, the bed-level changes of the tidal creek site displayed a contrary trend compared with those of the mudflat site, indicating the source-sink relationship between tidal creek and mudflat. During over-marsh tides, the tidal creek site with relatively high bed shear stresses (averagely, 0.37 N/m〈sup〉2〈/sup〉) was eroded by 35 mm whereas the mudflat site was accreted by 29 mm under low bed shear stresses (averagely, 0.18 N/m〈sup〉2〈/sup〉). To the contrast, during creek-restricted tides, deposition occurred in the tidal creek site by 20 mm under low bed shear stresses (averagely, 0.09 N/m〈sup〉2〈/sup〉) whereas erosion occurred in the mudflat site by 25 mm under relatively high bed shear stresses (averagely, 0.21 N/m〈sup〉2〈/sup〉). Over a spring-neap tidal cycle, the net bed level changes were −15 mm (erosion) and 4 mm (deposition) in tidal creeks and mudflats, respectively. These results suggested that there were alternated erosion-deposition patterns in spring and neap tides, and a sediment source and sink shift between mudflats and creeks. We found that the eroded sediments in mudflats were transported landward into tidal creeks and deposited therein in neap tides, and these newly deposited sediments would be resuspended and transported to surrounding marshes (over-marsh deposition) at spring tides. The coherent sediment transport and associated erosion-deposition pattern within the mudflat-creek system at spring-neap tidal time scales thus played a fundamental role in intertidal morphodynamic development. These findings suggest that management and restoration of intertidal ecosystem need to take the entire mudflat-creek-marsh system as a unit into consideration rather than focusing on single elements.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Adnan Rajib, Grey R. Evenson, Heather E. Golden, Charles R. Lane〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A hydrologic model, calibrated using only streamflow data, can produce acceptable streamflow simulation at the watershed outlet yet unrealistic representations of water balance across the landscape. Recent studies have demonstrated the potential of multi-objective calibration using remotely sensed evapotranspiration (ET) and gaged streamflow data to spatially improve the water balance. However, methodological clarity on how to “best” integrate ET data and model parameters in multi-objective model calibration to improve simulations is lacking. To address these limitations, we assessed how a spatially explicit, distributed calibration approach that uses (1) remotely sensed ET data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and (2) frequently overlooked biophysical parameters can improve the overall predictability of two key components of the water balance: streamflow and ET at different locations throughout the watershed. We used the Soil and Water Assessment Tool (SWAT), previously modified to represent hydrologic transport and filling-spilling of landscape depressions, in a large watershed of the Prairie Pothole Region, United States. We employed a novel stepwise series of calibration experiments to isolate the effects (on streamflow and simulated ET) of integrating biophysical parameters and spatially explicit remotely sensed ET data into model calibration. Results suggest that the inclusion of biophysical parameters involving vegetation dynamics and energy utilization mechanisms tend to increase model accuracy. Furthermore, we found that using a lumped, versus a spatially explicit, approach for integrating ET into model calibration produces a sub-optimal model state with no potential improvement in model performance across large spatial scales. However, when we utilized the same MODIS ET datasets but calibrated each sub-basin in the spatially explicit approach, water yield prediction uncertainty decreased, including a distinct improvement in the temporal and spatial accuracy of simulated ET and streamflow. This further resulted in a more realistic simulation of vegetation growth when compared to MODIS Leaf-Area Index data. These findings afford critical insights into the efficient integration of remotely sensed “big data” into hydrologic modeling and associated watershed management decisions. Our approach can be generalized and potentially replicated using other hydrologic models and remotely sensed data resources – and in different geophysical settings of the globe.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Saba Shaghaghi, Hossein Bonakdari, Azadeh Gholami, Ozgur Kisi, Jalal Shiri, Andrew D. Binns, Bahram Gharabaghi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Accurate prediction of the long-term average dimensions of alluvial stable channels is a significant problem in river engineering. The goal of this research is to investigate the effect of flow discharge (Q), mean sediment size (d〈sub〉50〈/sub〉) and Shields parameter (τ〈sup〉∗〈/sup〉) on the stable channel dimensions by employing non-linear regression (NLR) and two Artificial Intelligence (AI) methods, including: Generalized Structure of Group Method of Data Handling (GS-GMDH) neural network and Gene Expression Programming (GEP). Discharge, grain size and Shields parameter from 85 gaging stations situated in three stable Iranian rivers were used as input data for the three methods to estimate the water-surface width (W), average flow depth (D) and longitudinal slope (S) of the rivers. Based on the results, it was found that the GS-GMDH produced more accurate results for simulating the channel width with a Mean Absolute Relative Error (MARE) value of 0.055; and GEP produced better estimations for channel depth and slope with MARE values of 0.035 and 0.03, respectively. Furthermore, by employing Artificial Intelligence (AI) methods (GS-GMDH and GEP), the RMSE values decreased by 22%, 25% and 75% in predicting width, depth, and slope, respectively, compared to NLR method. The overall results showed that the AI methods generally produced better estimations than the non-linear regression method. To determine the effect of each input variable (Q, d〈sub〉50〈/sub〉, τ〈sup〉∗〈/sup〉) on the target variables (W, D, S), a sensitivity analysis comprising various combinations of input variables was conducted. Based on the results, the flow discharge had a dominant role on depth and width estimation of stable channels. In slope estimation, the most important parameter was τ〈sup〉∗〈/sup〉 and then d〈sub〉50〈/sub〉, while the discharge had a weak effect on slope prediction. In general, the Shields parameter was the most effective parameter in depth and specially slope estimation of stable channels.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Zhijun Dai, Xuefei Mei, Stephen E. Darby, Yaying Lou, Weihua Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Knowledge of the transfer of sediment through river systems is essential for understanding the physical, chemical and biological processes on the Earth’s surface. A holistic analysis of long-term records of water discharge, sediment transport, riverbed morphology and estuarine hydrology is here used to quantify spatial and temporal variations in fluvial sediment fluxes along the Changjiang River. We show that the establishment of the Three Gorges Dam (TGD) has directly changed the fluvial sediment-transport process by annually trapping 1.23 × 10〈sup〉8〈/sup〉 t of sediment. The upper Changjiang reach has switched from being the main sediment source before 2003 to a depositional sink of fluvial sediment subsequently. The major lakes, such as Dongting Lake and Poyang Lake, have shifted from being local sediment sinks before 2003 to sediment sources thereafter, such that they now provide sediment to the Changjiang River. Since the 2003 closure of the TGD the riverbed of the middle-lower Changjiang has become the major source of sediment being transmitted downstream, now providing almost 50% of the material entering the estuary. Shoals in the estuarine channels and landward sediment transport from the sea have become major sediment sources for the river estuary. We conclude that dams currently in preparation along the upper Changjiang reach and adjacent lakes may cause the cessation of sediment supply to downstream reaches. Rising sea levels and frequent storms may terminate landward sediment transport, increasing estuarine erosion and inducing seaward sediment transport. It can therefore be expected that substantial erosion could occur in the near future in the Changjiang estuary system.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Andres Patrignani, Tyson E. Ochsner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Large-scale in situ soil moisture monitoring networks are becoming increasingly valuable research tools, but existing networks feature almost exclusive deployment of stations in grassland vegetation. These grassland soil moisture observations are unlikely to adequately represent the real soil moisture patterns in landscapes with intermixed land cover types. Here we demonstrate the severity of the problem for one particular landscape and introduce a flexible new method for solving the problem. The specific objectives of this study were (i) to compare root-zone soil moisture dynamics of two dominant vegetation types across Oklahoma, grassland (observed) and winter wheat cropland (simulated); (ii) to relate the soil moisture dynamics of grassland and cropland vegetation using an artificial neural network (ANN) as an observation operator; and (iii) to use the resulting ANN to estimate the soil moisture spatial patterns for a landscape of intermixed grassland and wheat cropland. Root-zone soil moisture was represented by plant available water (PAW) in the top 0.8 m of the soil profile. PAW under grassland was calculated from 18 years of soil moisture observations at 83 stations of the Oklahoma Mesonet, whereas PAW under winter wheat was simulated for the same 83 locations using a calibrated and validated soil water balance model. Then, we trained an ANN to reproduce the simulated PAW under winter wheat using only six inputs: day of the year, latitude and longitude, measured PAW under grassland, and percent sand and clay. The resulting ANN was used, along with grassland soil moisture observations, to estimate the detailed soil moisture pattern for a 9 × 9 km〈sup〉2〈/sup〉 Soil Moisture Active Passive (SMAP) grid cell. The seasonal dynamics of root-zone PAW for grassland and winter wheat were strongly asynchronous, so grassland soil moisture observations rarely reflect cropland soil moisture conditions in the region. The simple ANN approach facilitated efficient and accurate prediction of the simulated PAW under winter wheat, RMSD = 21 mm and normalized RMSD = 0.17, using observed PAW under grassland as an input. This new method for estimating soil moisture under adjacent, contrasting land covers at a relatively low computational cost could be employed for any region and land cover pairing with training data available, and it may significantly enhance the applications of existing large-scale soil moisture monitoring networks.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Xianghui Lu, Yan Ju, Lifeng Wu, Junliang Fan, Fucang Zhang, Zhijun Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Accurate estimation of pan evaporation (E〈sub〉p〈/sub〉) is required for many applications, e.g., water resources management, irrigation system design and hydrological modeling. However, the estimation of E〈sub〉p〈/sub〉 for a target station can be difficult as a result of partial or complete lack of local meteorological data under many conditions. In this study, daily E〈sub〉p〈/sub〉 was estimated from local (target-station) and cross-station data in the Poyang Lake Watershed of China using four empirical models and three tree-based machine learning models, including M5 model tree (M5Tree), random forests (RF〈sub〉s〈/sub〉) and gradient boosting decision tree (GBDT). Daily meteorological data during 2001–2010 from 16 weather stations were used to train the models, while the data from 2011 to 2015 were used for testing. Two cross-station applications were considered between each of the 16 stations and the other 15 stations. The results showed that the radiation-based Priestley-Taylor model (on average RMSE = 1.13 mm d〈sup〉−1〈/sup〉, NSE = 0.53, R〈sup〉2〈/sup〉 = 0.57, MBE = 0.21 mm d〈sup〉−1〈/sup〉) gave the most accurate daily E〈sub〉p〈/sub〉 estimates among the four empirical models during testing, while the mass transfer-based Trabert model (on average RMSE = 1.38 mm d〈sup〉−1〈/sup〉, NSE = 0.25, R〈sup〉2〈/sup〉 = 0.46, MBE = 0.65 mm d〈sup〉−1〈/sup〉) performed worst. The GBDT model outperformed the RF〈sub〉s〈/sub〉 model, M5Tree model and the empirical models under the same input combinations in terms of prediction accuracy (on average RMSE = 0.86 mm d〈sup〉−1〈/sup〉, NSE = 0.68, R〈sup〉2〈/sup〉 = 0.73, MBE = 0.07 mm d〈sup〉−1〈/sup〉) and model stability (average percentage increase in testing RMSE = 16.3%). The RMSE values generally increased with the increase in the distance of two cross stations. A distance of less than 100 km between two cross stations is highly recommended for cross-station applications with satisfactory prediction accuracy (median percentage increase in RMSE 〈5% for cross-station application #1 and 〈20% for application #2) in the Poyang Lake Watershed of China and maybe elsewhere with similar climates.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Yukiyoshi Iwata, Yosuke Yanai, Tomotsugu Yazaki, Tomoyoshi Hirota〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A frozen soil layer may impede snowmelt infiltration, resulting in a large amount of runoff that influences the soil water balance and anion movement in the soil profile. To examine the relationships among soil frost depth, snowmelt runoff, and nitrate leaching in agricultural fields, we measured both the snowmelt runoff for three winters and other environmental factors including the soil frost depth and nitrate content in a ∼10,000 m〈sup〉2〈/sup〉 field. We divided the field into two subplots: one was maintained in a natural snow cover condition (the control plot), and the snow cover was compacted on the other plot (the treated plot) to enhance the development of the soil frost depth. In all three winters, soil frost depths in the control plot were 〈0.2 m and very little runoff was observed during the snowmelt period. In contrast, the soil frost depth became 〉0.4 m and a large amount of snowmelt runoff was observed in the treated plot. The depth of the peak nitrate concentration after the snowmelt period was shallower in the treated plot compared to the control plot. Moreover, a significant linear relationship was observed between (1) the amount of nitrate in the 0–0.3 m depth after the snowmelt period and (2) the total amount of snowmelt infiltration calculated by subtracting the amount of snowmelt runoff from the amount of snowmelt water. These results suggest that snow compaction can be a promising technique to develop a uniform soil frost depth in large-scale fields, which consequently controls the soil water and nutrient movement in the soil layer.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418307777-ga1.jpg" width="487" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Zhongyang Li, Di Wang, Xiaoxian Zhang, John W Crawford〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Water flow along or across the interfaces of contrasting materials is ubiquitous in hydrology and how to solve them in macroscopic models derived from volumetric average of the pore-scale processes remains elusive. While the change in the average velocity and pressure at water-sediment interface has been well established for channel flow over porous beds, whether a volumetric average alerts the pressure continuity when water flows across the interface of two porous materials is poorly understood despite its imperative implications in hydrological modelling. The primary purpose of this paper is to provide evidences via pore-scale simulations that volumetrically averaging the pore-scale processes indeed yields a discontinuous pressure when water flows across a material interface. We simulated two columns numerically reconstructed by filling them with stratified media: One is an idealised two-layer system and the other one is a 3D column filled by fine glass beads over coarse glass beads with their pore geometry acquired using x-ray computed tomography. The pore-scale simulation is to mimic the column experiment by driving fluid to flow through the void space under an externally imposed pressure gradient. Once fluid flow reaches steady state, its velocity and pressure in all voxels are sampled and they are then spatially averaged over each section perpendicular to the average flow direction. The results show that the average pressure drops abruptly at the material interface no matter which direction the fluid flows. Compared with the effective permeability estimated from the homogenization methods well established in the literature, the emerged discontinuous pressure at the interface reduces the combined ability of the two strata to conduct water. It is also found that under certain circumstances fluid flow is direction-dependant, moving faster when flowing in the fine-coarse direction than in the coarse-to-fine direction under the same pressure gradient. Although significant efforts are needed to incorporate these findings into practical models, we do elicit the emergence of discontinuous pressure at material interface due to volumetric average as well as its consequent implications in modelling of flow in heterogeneous and stratified media.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Zi Wu, Arvind Singh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Associated with Taylor dispersion, in this paper we analyze how the vertical position of a point-source solute release will affect the transport process in laminar open channel flow, through obtaining and applying analytical solution by the two-scale perturbation analysis (Wu and Chen, 2014, J. Fluid Mech., 740, 196–213), which is verified and supported by results from numerical simulations. Based on multi-dimensional spatial concentration distribution of the solute plume, we resort to the previously proposed criterion for identifying the stage of solute transport characterized by the dispersion-dominated (Taylor dispersion) regime, focusing on the relative uniformity of concentration distribution across a given family of curved surfaces (Wu et al., 2016, Sci. Rep., 6, 20556). The most important finding is that for the solute transport transition into the dispersion-dominated regime, the necessary time is about 50% more for the case of solute release at free water surface compared with that at the channel bed, which is substantial under typical physical parameters. Other effects of release position include affecting the displacement of the solute plume centroid, the value of the maximum mean concentration, and non-Gaussian properties regarding the form of the streamwise distribution of the mean concentration.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Donovan C. Capes, Colby M. Steelman, Beth L. Parker〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study evaluates the utility of ambient temperature profiles collected in sealed bedrock boreholes to assess variability in groundwater flow in discretely fractured shallow bedrock environments. A conceptual model for groundwater flow and groundwater-surface water temperature conditions and their interaction in a temperate climate is developed through a statistical interpretation of time-lapse thermal deviation logs. Temperature profiles were collected in three angled and three vertical boreholes drilled to 24–32 mbgs (meters below ground surface) and temporarily sealed with an impermeable fabric liner in a fractured dolostone bedrock aquifer adjacent to and extending beneath a bedrock river to monitor seasonal hydrodynamics. Ambient borehole temperature profiles collected every 1–8 weeks over a 12 month period identified zones of hydraulic activity during periods of intra-seasonal stability without the interference of open borehole cross-connection. Signal cross-correlation and Fourier spectra analysis of thermal deviation logs provided a novel way to observe the shallow bedrock flow system’s temperature evolution due to advection along discrete fractures in response to seasonal transience, and to identify and isolate noise caused by free-convection cells within the sealed borehole. This approach represents a diagnostic tool that improves confidence in identifying depth discrete, hydraulically active fracture zones from thermal deviation data sets in a shallow, fractured sedimentary bedrock environment. Variably scaled free-convection cells were observed within the borehole water columns during the colder winter periods. Although these periods were accompanied by higher signal noise near the river/atmospheric interface, these cells led to a temporary thermal disequilibrium between the borehole water column and formation water deeper in the bedrock. These conditions increased the maximum depth of thermal detections associated with discrete groundwater flow features from 14 mbgs in the summer to 26 mbgs in the winter, thereby enhancing the understanding of shallow groundwater flow systems under the direct influence of surface water.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Jeremie Bonneau, Tim D. Fletcher, Justin F. Costelloe, Peter J. Poelsma, Robert B. James, Matthew J. Burns〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The practice of stormwater infiltration is widely used to reduce the amount of urban stormwater runoff delivered to drainage systems and receiving waters. In theory, the practice recharges groundwater, leading to increased urban stream baseflow. In reality, however, little is known about the fate of infiltrated stormwater. Because urban groundwater pathways are numerous and the interactions with subsurface infrastructure (e.g. trenches, pipes, etc.) are highly complex, the spatial and temporal variability of the contribution of infiltrated stormwater to baseflow is difficult to predict. We tracked the fate of infiltrated stormwater out of an 1800 m〈sup〉2〈/sup〉 infiltration basin (3.5% of its 5-ha impervious catchment) using a network of piezometers for over three years. We found that groundwater levels downslope of the basin were increased (up to 4 m) while water levels in an array of reference piezometers lateral to the basin showed no change (dry at depths ranging 2–4 m). Monthly water balance calculations indicated that in summer, most of the infiltrated stormwater was evapotranspired by the vegetation downslope of the basin, and thus did not reach the receiving stream. In the colder months, some infiltrated stormwater did reach the stream as plant water use declined. Anthropogenic disturbances (a sewer pipe and stream re-alignment) interacted with the upper part of the plume of infiltrated stormwater, locally lowering the water table. The study provides evidence that the fate of infiltrated stormwater is complex, and that infiltrated stormwater does not always reach receiving streams as baseflow as is often assumed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Martin Durocher, Donald H. Burn, Shabnam Mostofi Zadeh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Region of influence is a common approach to estimate runoff information at ungauged locations. To estimate flood quantiles from annual maximum discharges, the Generalized Least Squares (GLS) framework has been recommended to account for unequal sampling variance and intersite correlation, which requires a proper evaluation of the sampling covariance structure. Since some jurisdictions do not have clear guidelines to perform this evaluation, a general procedure using copulas and a nonparametric intersite correlation model is investigated to estimate sampling covariance structure in situations where no common at-site distribution is imposed or when some paired sites do not have common periods of record. The investigated methodology is applied on 771 sites in Canada. The Normal copula is verified to be an adequate model that better fit paired observations than other types of extreme copulas. A sensitivity analysis is carried out to evaluate the impact of either ignoring, or considering a simpler form of, intersite correlation. Additionally, super regions are defined based on drainage area and mean annual precipitation to improve the calibration of pooling groups across large territories and a wide range of climate conditions. Performance criteria based on cross-validation revealed that using super regions and a combination of geographic distance and similarity between catchment descriptors improves the calibration of the pooling groups by providing more accurate estimates.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Zhiyong Wu, Jianhong Zhou, Hai He, Qingxia Lin, Xiaotao Wu, Zhengguang Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to obtain an improved soil moisture (SM) dataset at large scale, an advanced SM merging methodology based on error correction methods was constructed to merge the model-based and in-situ observed SM data. The SM datasets in a 0–40 cm soil layer were derived from 10 km × 10 km Variable Infiltration Capacity (VIC) model and 797 in-situ stations, respectively. The merging methodology was conducted grid by grid, and mainly included two parts: bias correction and random error correction. Firstly, the bias correction was performed for the VIC simulations by applying the Cumulative Distribution Function (CDF) matching approach combined with the kriging technique. Secondly, the random error of the VIC simulations was corrected using an Optimal Interpolation (OI) technique based on a spatio-temporal correlation function which was proposed and constructed in this study. Through validations against in-situ observations, the merged SM was evaluated, and the merging errors in each step were analyzed and discussed. The results showed that the merged SM product was improved compared to the original SM data, both temporally and spatially. The SM merging methodology is effective and reliable in combining the accurate but sparse in-situ observations and the continuous VIC simulations. In addition, the spatial mismatch impact on the representativeness of in-situ stations was limited, and the merging errors were mainly produced in the CDF estimation process. The random error information in the spatial dimension exhibited a bigger impact on the random error correction comparing to that in the temporal dimension. This study provided strong encouragement for the efficient use of in-situ SM observations and provided valuable methods for combining multi-sources SM datasets.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Peng Bai, Xiaomang Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Accurate quantification of large-scale evapotranspiration (ET) has an important scientific and practical significance. In this study, three global high-resolution ET products were intercompared and evaluated across China; the evaluated ET products were the Global Land Evaporation Amsterdam Model (GLEAM) version 3.2, the Global Land Data Assimilation System (GLDAS) version 2.0 Catchment Land Surface Model (CLSM) dataset, and the Numerical Terradynamic Simulation Group (NTSG) dataset. The evaluations were performed at the site scale with eddy covariance (EC) based observations from eight flux stations, and at the basin scale with water balance-based ET estimates from 22 river basins in China. The intercomparison results indicated that the three products consistently presented an increasing trend over a large proportion of China but large differences in the trend of the annual ET and the mean annual ET estimates. The trends of the annual ET estimates derived from the GLEAM, GLDAS, and NTSG products are 0.449, 0.904 and 1.261 mm/yr〈sup〉2〈/sup〉, respectively; the countrywide mean annual ET derived from the three products are 390.2, 443.4 and 419.9 mm/yr, respectively. The site-scale evaluation results indicated that the GLEAM and NTSG products achieved comparable consistencies with the monthly gauge observations and outperformed the GLDAS product; GLEAM was more consistent with the daily gauge observations than GLDAS. At the basin scale, all three products were unable to reasonably reproduce the water balance-based annual ET time series in most basins; the three products systematically overestimated ET in the wet basins compared with the water balance-based ET estimates. The differences in the ET estimates among the ET products may be largely attributed to the discrepancies in the forcing data and model algorithms.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Iman Mallakpour, Mojtaba Sadegh, Amir AghaKouchak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, we investigate changes in future streamflows in California using bias-corrected and routed streamflows derived from global climate model (GCM) simulations under two representative concentration pathways (RCPs): RCP4.5 and RCP8.5. Unlike previous studies that have focused mainly on the mean streamflow, annual maxima or seasonality, we focus on projected changes across the distribution of streamflow and the underlying causes. We report opposing trends in the two tails of the future streamflow simulations: lower low flows and higher high flows with no change in the overall mean of future flows relative to the historical baseline (statistically significant at 0.05 level). Furthermore, results show that streamflow is projected to increase during most of the rainy season (December to March) while it is expected to decrease in the rest of the year (i.e., wetter rainy seasons, and drier dry seasons). We argue that the projected changes to streamflow in California are driven by the expected changes to snow patterns and precipitation extremes in a warming climate. Changes to future low flows and extreme high flows can have significant implications for water resource planning, drought management, and infrastructure design and risk assessment.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): S. Gharari, S. Razavi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hysteresis is a widely reported phenomenon in natural and engineered systems across different temporal and spatial scales. Its definition is non-unique and rather context-dependent, while systems with hysteretic behavior, including hydrological systems, are commonly referred to as path-dependent systems or systems with memory. Despite widespread existence of hysteretic processes, the current generation of hydrologic models do not directly account for hysteresis. In this paper, we review the fundamentals, theories, and general properties of hysteresis in the broad scientific literature and then focus on its representations in hydrological sciences. Through illustrative examples, we show how an incomplete understanding or representation of the underlying processes in a system can lead to considering the system as being path-dependent. We argue that, in most cases, hysteresis is a manifestation of our dimensionality-reducing approach to process understanding and representation. We further explain that modelling hysteresis in an ideal world requires a full-dimensional process representation, based on a perfect understanding of the processes, their heterogeneity, and their spatio-temporal scale dependency. We discuss, however, that the missing dimensions/physics in a hydrologic model may be compensated to some extent by enabling the model with formal hysteretic components. Moreover, we show that the conventional model structure and parameterization may be designed in a way to partially reproduce a desired hysteretic behavior.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Deqiang Mao, Zaibin Liu, Wenke Wang, Shucai Li, Yaoquan Gao, Zhenhao Xu, Chi Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Water inrush incidents threaten the safety of coal mining. Understanding of hydrogeologic parameter distributions is critical for preventing water-related hazards in coal mines. During the deep mining (〉1000 m) under the North China Plain, water from water-bearing strata discharges into coal seams through geologic conduits (i.e. water inrush) due to the fractured zone under the floor of working faces. In this study, a water inrush incident was exploited as an active stimulus. A 3D groundwater flow model was built for the eighth member of the Middle Ordovician system in Xingdong coal mine. Using this model and an inverse approach, we first checked if the data from the incident and an independent pumping test carry non-redundant information about the heterogeneity of the mine. Afterward, we combined these datasets to conduct a large-scale (approximately 10 km) hydraulic tomography (HT) analysis. The estimated hydraulic conductivity distribution from the HT analysis is found consistent with the distribution of known geologic faults. That is, a cluster of faults is characterized as a high-conductivity zone. A high conductivity zone is identified at locations close to the water inrush location, which is the high cement consumption zone during the grouting project. Finally, results of this study promote exploiting the water inrush events as a HT survey for mapping geologic structures over a large area.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Yavuz Selim Güçlü〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The climate change is an important event that affects hydrological, agricultural and water resources planning variables, and therefore, the hydrologists and meteorologists frequently try to identify trend possibilities especially in rainfall, runoff and temperature time series. For this purpose, the classical Mann-Kendall (MK), Spearman’s rho (SR), Sen’s slope, and linear regression approaches are applied frequently in the literature. Recently, innovative trend analysis (ITA) provides visual inspection and identification of categorical trends, which is one of the main concerns in this paper. On the basis of ITA methodology, several improvements namely double-ITA (D-ITA) and triple-ITA (T-ITA) procedures are suggested using with simple ITA together. These methods are attractive for the trend stability assessment by comparing partial trend components during different sub-periods of a given record series. Furthermore, partial MK test approach is proposed in this paper for the same purpose. These procedures and approach are applied to a set of annual rainfall records at many stations in different regions of Turkey. As a result, the comparison of the suggested methods based on partial sub-series of the same time series helps to improve trend detection with stability identification.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Bree Bennett, Michael Leonard, Yu Deng, Seth Westra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The magnitude of floods depends not only on the intensity and pattern of precipitation during the flood event (the ‘flood-producing’ precipitation), but also on the moisture stored in the catchment, which arises from antecedent hydrological processes over many preceding timescales. To characterise this effect, an empirical study is conducted on the influence of antecedent precipitation on significant flood events across multiple climate zones and catchment conditions, using 100 Australian catchments with hourly streamflow and precipitation. Antecedent conditions are shown to have a significant influence on flood volume, with three quarters of catchments having at least a 50% difference in flood volume depending on whether the catchment is wet or dry before the flood-producing precipitation event. The study considers the sensitivity of flow to antecedent precipitation by means of an ‘elasticity’ metric, which indicates the proportional change in flow for a change in antecedent precipitation or flood-producing precipitation. Flood-producing precipitation nevertheless remains the dominant flood driver across most catchments, with the elasticity of flow to antecedent precipitation typically being between 28% and 37% of the elasticity to flood-producing precipitation. Importantly, the elasticity of flow to antecedent precipitation relative to flood-producing precipitation decreases with increasing event magnitude, highlighting that conclusions of future change based on annual maximum streamflow may not be reflective of the processes that operate for more extreme floods that have the greatest impact on society.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Yize Yang, Huiling Yuan, Wei Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Parameter calibration and uncertainty estimation are crucial for hydrological simulations in the distributed land surface-hydrological model. To investigate soil properties impacting hydrological processes, five conventional pedo-transfer functions (PTFs) are applied to create a 3D soil hydraulic parameter (SHP) ensemble in the Weather Research and Forecasting-Hydrological extension (WRF-Hydro), a distributed, multi-physics land surface hydrological model. The SHPs are generated, based on a high-resolution Chinese soil property dataset, over the heterogeneous Upper Huaihe River basin. The results show that the SHPs can influence the streamflow in WRF-Hydro, which is similar to the impact of the scaling parameters on the streamflow over the study basin. Analyses of the uncertainty in the SHP ensemble reveal that SHPs mainly constrain the peak flow during the flood rise and impact the baseflow during the flood recession. A hydrological Bayesian model average (BMA) method is constructed to postprocess the streamflow ensemble based on the 3D SHPs. Probabilistic streamflow estimations by the BMA method are more skillful than the simulations using the individual 3D SHP ensemble members for all five studied hydrological stations, especially for high flows. Therefore, improved estimation of the uncertainty in the 3D SHPs may enhance the spatial representation of flood processes, resulting in more accurate estimates of the streamflow in the main streams in a heterogeneous basin.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Jisha Joseph, Subimal Ghosh, Amey Pathak, A.K. Sahai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Assessing impacts of climate change on hydrology involves global scale climate projections by General Circulation Models (GCMs), downscaling of global scale projections to regional scale by statistical methods or regional climate models and then use of regional outputs in hydrological simulations. Hydrological simulations considers varying inputs starting with soil characteristics, land cover, vegetation types, control structures to social parameters such as human interventions, irrigation and water use. This makes the model highly parametrized and at the same time highly uncertain due to the non-availability of majority of input parameters. Here, we compare the contributions of uncertainty from hydrological parameterization in the hydrological projections of climate change to that generated from the use of multiple climate models. The Ganga River Basin in India was selected as the study region. For regional climate change projections, we use dynamic downscaling outputs from Coordinated Regional Climate Downscaling Experiment (CORDEX) and statistical downscaling outputs from a transfer function forced with 3 GCMs, Institut Pierre Simon Laplace (IPSL), European Consortium Earth System Model (EC-EARTH) and MPI (Max Plank Institut) ESM (Earth System Model). Monte-Carlo Simulations (MCS) are performed with 1000 generated sets of sensitive model parameters for each of the GCM-regional model combination. We find that the observed time series of river discharge is reproduced well but with bias in low-flow conditions. This is probably associated with human intervention and poor representation of baseflow in VIC due to the neglected groundwater storage which feed the surface water during low flow condition. The future projections show that the major uncertainty lies across climate models for all the four seasons (MAM, JJAS, ON and DJF) and for all the hydrological variables, soil moisture, evapotranspiration (ET), water yield and river discharge. The uncertainty resulting from the MCS is quite small as compared to the climate model uncertainty. We are unable to find any added value in hydrological simulations by rigorous hydrological calibration and parameterization in absence of many required data, when the forcing meteorological data has huge uncertainty. Our findings highlight the need of convergence of climate models before the studies on hydrological impacts assessment and subsequent development of adaptation strategies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Xiaolin Qiu, Ya Wang, Zhongzheng Wang, Klaus Regenauer-Lieb, Ke Zhang, Jie Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Medium–low temperature geothermal resources are abundant in Southern China, but their heat source and link to fault zones is poorly understood. Consequently, geothermal energy is only used at small scale. In order to broaden the footprint of geothermal energy use in Southern China, it is first necessary to understand and track the geothermal groundwater circulation pattern associated with fault zones. The Heyuan Fault Zone serves as a typical medium–low temperature geothermal system of South China. Here we show that the geothermal groundwater circulation pattern can be traced by using stable hydrogen and oxygen isotopes, helium and neon isotopes, carbon-13 and carbon-14 as well as hydrochemical parameters. The results show that: in the Heyuan Fault Zone, the main hydrochemical type of the hot springs is HCO〈sub〉3〈/sub〉-Na + K, while the shallow cold groundwater is mainly enriched in HCO〈sub〉3〈/sub〉-Ca. The results of the helium isotope and neon isotope indicate that the geothermal groundwater of this area is derived from the crust, thus excluding the possibility of extremely deep paths of groundwater tapping into mantle helium sources. Furthermore, the characteristics of the stable hydrogen and oxygen isotopes imply that geothermal groundwater is of local meteoric origin, and the recharge area located at the hilly area of the hanging wall of the Heyuan main fault, with the recharge elevations ranging from about 440 m to 670 m. The hot spring geothermometer shows that the highest reservoir temperature is about 157 °C, and the deepest circulation depth is about 6500 m. Carbon-14 isotope age dating suggests that the geothermal groundwater ages are mostly from 9.9 kyr BP to 12.3 kyr BP. According to the geological structural characteristics of the study area, the main upward channel for geothermal groundwater is the Heyuan main fault. Generally, the hot springs in this area are mixed with shallow cold groundwater and surface water, which raises the ratio of the Ca〈sup〉2+〈/sup〉 in water and dilutes the heavy hydrogen and oxygen isotopes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Khabat Khosravi, Luca Mao, Ozgur Kisi, Zaher Mundher Yaseen, Shamsuddin Shahid〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Suspended sediment has significant effects on reservoir storage capacity, the operation of hydraulic structures and river morphology. Hence, modeling suspended sediment loads (SSL) in rivers contributes to various water resource management and river engineering. An evaluation of stand-alone data mining models (i.e., reduced error pruning tree (REPT), M5P and instance-based learning (IBK)) and hybrid models, (i.e., bagging-M5P, random committee-REPT (RC-REPT) and random subspace-REPT (RS-REPT)) for predicting SSL resulting from glacial melting at an Andean catchment in Chile has been conducted in this study. The best input combinations are constructed based on Pearson correlation coefficient (PCC) of hourly SSL time series data with water discharge (Q), water temperature (T) and electrical conductivity (C) for different time lags. Seventy percent of the available data (one year of hourly data) is used to calibrate the models (dataset training) and the remaining 30% is used for model evaluation (dataset testing). The performances of the models are evaluated using several quantitative and graphical criteria, including coefficient of determination (R2), root mean square error (〈em〉RMSE〈/em〉), mean absolute error (〈em〉MAE〈/em〉), Nash-Sutcliffe efficiency (〈em〉NSE〈/em〉), percentage of bias (〈em〉PBIAS〈/em〉), the ratio of RMSE to the standard deviation of observation (〈em〉RSR〈/em〉), a Taylor diagram and a boxplot. All the models performed well in predicting SSL. However, the Friedman and Wilcoxon signed rank tests revealed that predicted SSL significantly differed for different models except between IBK (or M5P) and REPT. The hybrid models performed better than individual models. The bagging-M5P had the best predictive capability while the REPT had the poorest.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Shams Al-Amin, Emily Z. Berglund, G. Mahinthakumar, Kelli L. Larson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Groundwater resources are shared across management boundaries. Multiple management units that differ in scale, constraints and objectives may manage a shared resource in a decentralized approach. The interactions among water managers, water users, and the water resource components influence the performance of management strategies and the resilience of community-level water supply and groundwater availability. This research develops an agent-based modeling (ABM) framework to capture the dynamic interactions among household-level consumers and policy makers to simulate water demands. The ABM is coupled with a groundwater model to evaluate effects on the groundwater table. The framework is applied to explore trade-offs between improvements in water supply sustainability for local resources and water table changes at the basin-level. A group of municipalities are simulated as agents who share access to a groundwater aquifer in Verde River Basin, Arizona. The framework provides a holistic approach to incorporate water user, municipal, and basin level objectives in evaluating water reduction strategies for long-term water resilience.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): F.A.L. Pacheco, L.M.O. Martins, M. Quininha, A. Sousa Oliveira, L.F. Sanches Fernandes〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mountainous headwater catchments are safeguards of quality groundwater and hence require special protection against contamination by anthropogenic sources. However, methods currently handling contamination risk fail to produce reliable results in mountainous watersheds because they overlook the influence of downhill flows and contaminant transport in the validation process. To overcome this difficulty, a new model based on so-called “concentration profiles” is presented that combines the DRASTIC framework for evaluation of intrinsic vulnerability, the categorization of land uses for evaluation of specific vulnerability to nitrate and Processing Modflow graphical user interface for simulation of nitrate transport. This model was tested in a mountainous region of Northern Portugal. The risk of groundwater contamination by nitrate was generally classified as moderate. The risky areas are regions used for agriculture and livestock production. These activities have raised nitrate concentrations of spring water (15–25 mg·L〈sup〉−1〈/sup〉) downstream the risky areas. The Modflow simulations linked the risky areas (contaminant sources) to actual nitrate plumes (contaminant sinks) and modeled nitrate distributions at specific groundwater travel times. Winter plumes could be simulated for the 1-year stress period, and hence are flushable in a short time span. Spring and summer plumes could only be explained by contaminant transport during 10–20 years. In these cases, even if contaminant sources were immediately neutralized, the washout of nitrate would take decades. These results may hold back the fulfillment of sustainable development goals related to water and sanitation until 2030, and hence deserve reflection by water planners and policy makers. The modeling exercise provided extra evidence that safeguarding the catchment headwater is the keystone of groundwater quality protection in mountainous catchments. Therefore, application of this modified DRASTIC to other mountainous areas may not need to resort to Processing Modflow. The study comprises the main paper (this paper) and a MethodsX companion paper.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418306991-ga1.jpg" width="350" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): A. Shakas, N. Linde, T. Le Borgne, O. Bour〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fracture-scale heterogeneity plays an important role in driving dispersion, mixing and heat transfer in fractured rocks. Current approaches to characterize fracture scale flow and transport processes largely rely on indirect information based on the interpretation of tracer tests. Geophysical techniques used in parallel with tracer tests can offer time-lapse images indicative of the migration of electrically-conductive tracers away from the injection location. In this study, we present a methodology to invert time-lapse ground penetrating radar reflection monitoring data acquired during a push-pull tracer test to infer fracture-scale transport patterns and aperture distribution. We do this by using a probabilistic inversion based on a Markov chain Monte Carlo algorithm. After demonstration on a synthetic dataset, we apply the new inversion method to field data. Our main findings are that the marginal distribution of local fracture apertures is well resolved and that the field site is characterized by strong flow channeling, which is consistent with interpretations of heat tracer tests in the same injection fracture.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): David Sevillano, Patricia T. Romero-Lastra, Inmaculada Casado, Luis Alou, Natalia González, Luis Collado, Adelaida A. Domínguez, Caridad M. Arias, Iluminada Corvillo, Francisco Armijo, Margarita Romero, Francisco Maraver〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉In order to assess the role of the biotic and abiotic components of natural mineral water (NMW) in the spread of allochthonous bacteria in non-thermal spa facilities, we examined the effect of low mineralized NMWs on the growth of several commensal and pathogenic human strains. These NMWs were collected from two Spanish spring spas and had different microbiological characteristics.〈/p〉 〈p〉Microorganisms were exposed to untreated, filtered and autoclaved NMWs at the temperatures of 22 °C and 37 °C for 2 days, mimicking the early stage of starvation. Starvation stress was controlled by the effect identified after incubation in saline. Changes in culturability after exposure were used as a measure of the water’s antibacterial effect. The specific biotic and abiotic effect of NMWs on the suppression of bacterial growth was estimated after excluding the bacterial response to starvation stress, characteristic of this natural oligotrophic environment.〈/p〉 〈p〉The incubation temperature strongly modulated both the consequences of starvation and the impact of the natural biotic and abiotic components of NMWs on the growth of commensal and pathogenic bacteria. A temperature of 22 °C conferred cross-protection of microorganisms to starvation and NMW abiotic stress, whereas a temperature of 37 °C decreased the tolerance to both, and had a negative influence on the abundance and diversity of NMWs microflora. This temperature-dependent behaviour of the allochthonous and autochthonous bacteria explained the different culturability of microorganisms after exposure to untreated NMWs at 22 °C (≈1–2.4 log colony forming units per ml -CFU/ml- mean reduction) and at 37 °C (≈1.8–3.2 log CFU/ml mean reduction).〈/p〉 〈p〉Discarding the effect of starvation, we estimated that the antibacterial effect of NMWs at the temperature of 22 °C was mainly driven by the microecosystem of NMWs, which explained ≥95% of NMW response. In contrast, at optimal temperatures for the growth of commensal and pathogenic microorganisms, ≥60% of the antibacterial response of NMWs was associated with the abiotic components of NMWs.〈/p〉 〈p〉The biotic and abiotic components of NMWs self-preserve the quality of water, preventing the progression of human pathogenic organisms that can occasionally cause water colonization. The influence of the intrinsic components of NMWs on the suppression of microbial growth is strongly modulated by environmental temperature.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Milad Nouri, Mehdi Homaee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study was conducted to evaluate the performance of temperature-based models i.e. temperature-based Penman-Monteith FAO 56 fed with average wind speed (U) value (TPM〈sub〉U〈/sub〉) and default U quantity (TPM〈sub〉2〈/sub〉), Hargreaves-Samani (HS) and FAO Blaney-Criddle (FBC) against Penman-Monteith FAO 56 (PM) using data recorded in 1993–2015 at 146 sites over Iran. Two statistics i.e. normalized Root Mean Square (nRMSE) and relative Mean Bias Error (rMBE) were calculated to analyze the absolute error and bias magnitude of the temperature-based ET〈sub〉0〈/sub〉 estimation, respectively. Except for the December-January-February (DJF), the models gave reliable seasonal estimates (i.e. nRMSE of 30 〉 %) for the majority of studied areas. At monthly scale, FBC gave poor estimates of ET〈sub〉0〈/sub〉 in DJF for more than 60% of semi-arid and sub/humid-humid sites. ET〈sub〉0〈/sub〉 in December and January was not also modeled reliably by TPM〈sub〉2〈/sub〉 for 61 and 52% of the semi-arid and sub/humid-humid sites, respectively. Hence, application of FBC and TPM〈sub〉2〈/sub〉 appears not to be recommendable in cold areas and months over Iran. Overall, TPM〈sub〉U〈/sub〉 and HS are better suited at all temporal scales under data limitation over the studied areas. In the case of data availability, calculation of TPM with local average U (instead of default quantity of 2 m s〈sup〉−1〈/sup〉) is highly likely to improve the estimation accuracy. Seasonal and monthly ET〈sub〉0〈/sub〉 were mostly underestimated over the hyper-arid/arid sites during the March-April-May (MAM) and June-July-August (JJA). However, TPM〈sub〉2〈/sub〉 and HS overestimated ET〈sub〉0〈/sub〉 for the majority of semi-arid and sub-humid/humid areas. The U anomalies were identified as the primary contributing factor to the error in temperature-based ET〈sub〉0〈/sub〉 estimation for most cases. TPM〈sub〉2〈/sub〉, HS and FBC provided more accurate estimates for the U range of 1.5–2.5 m s〈sup〉−1〈/sup〉. These findings are of significant practical importance for agricultural, hydrological and climatic studies and applications under data sparse condition.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Bahija Alabjah, Fouad Amraoui, Mohamed Chibout, Mohamed Slimani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The coastal Chaouia, located on the Moroccan Atlantic coast, comports three aquifers: a first Plio-quaternary constitutes the cover, a second Cretaceous located at SW in the zone of Azemmour-Tnine Chtouka, and a third Primary located at SE in the zone of Tnine Chtouka-Casablanca. These reservoirs constitute the only exploitable water resource for the social and economic development of the region between Azemmour and Casablanca. These aquifers are unconfined, pellicular, and discontinuous. They feed by infiltration of rainwater and discharge at sea. Agricultural irrigation is carried out exclusively from the groundwater, which causes a drop of the piezometric surface and the intrusion of saltwater into the aquifer at the coast. The consequence is the abandonment of some wells contaminated by seawater leading to conflict situations and significant economic losses. Therefore, delineation of the freshwater/saltwater interface is very important in order to build a sustainable groundwater management system and to implement appropriate regulatory policies.〈/p〉 〈p〉The purpose of this study is to determine the extent and the geometric characteristics of the saltwater contamination extent in the coastal aquifers of the coastal Chaouia. To achieve this, 399 vertical electric soundings and 48 electrical resistivity tomography profiles were performed perpendicular to the ocean. Furthermore, the electrical conductivity and the piezometry were measured in 344 wells distributed over the study area.〈/p〉 〈p〉The study demonstrated the effectiveness of electrical methods for mapping seawater intrusion into coastal aquifers. In fact, the results of the interpretation of the VES and ERTs after calibration with the lithological data of the boreholes, as well as the values of the electrical conductivity, have shown that the length of the saltwater wedge penetration inland depends on the lithological nature of the aquifer formations. Thus, in the zone of Azemmour – Tnine Chtouka, characterized by the presence of Cretaceous terrains, the extension of the saltwater wedge exceeds 2 km towards the continent and its depth reaches 45 m. On the other hand, in the zone of Tnine Chtouka- Casablanca, characterized by the rise of the schists surmounted by the altered schists the seawater intrusion remains limited at 700 m from the coast and at 20 m of depth.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418306899-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Abbas Sedghamiz, Mohammad Reza Nikoo, Manouchehr Heidarpour, Mojtaba Sadegh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, a mathematical model for conflict resolution among a diverse set of agricultural water users in Golestan province, Iran, is developed. Given the bi-level nature of the distribution of power in the current problem, a combination of Leader–Follower game and Nash–Harsanyi bargaining solution method is employed to find optimal water and crop area allocations. The Golestan Regional Water Authority is the leader in this setting, controlling the total water allocations; and the agricultural sectors are the followers, competing over the allocated water. Two objectives for the leader are (i) maximizing profits, and (ii) maximizing share of green water in total agricultural production through selecting more efficient crop patterns. The followers’ objective is merely maximizing obtained benefits for the selected crop patterns. Virtual water concept is also factored into the related objective functions, and the water allocation problem is solved considering spatio-temporal crop pattern along with a dynamic water pricing system. This involves using a hybrid optimization structure as a new approach to solving two level optimization problems. The results show that the leader’s income is independent of total water allocation and is only affected by crop pattern and crop area, two factors which drive water price too. The followers’ benefit also depends on crop pattern and crop area, as they influence the crop yield, cost and water price. Finally, green water plays a key role in selecting the optimal crop pattern and crop area.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Daniel Bittner, Tahoora Sheikhy Narany, Bernhard Kohl, Markus Disse, Gabriele Chiogna〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrological models represent valuable tools to investigate the impacts of land use changes on water resources. Most commonly, distributed, physically-based models are applied for land use change impact studies in hydrology. However, providing a physically-based and detailed description of subsurface flows in karst systems is challenging. Lumped models, in contrast, are easy to implement and widely used in karst hydrological research, albeit not applicable for land use change impact studies. To overcome these limitations, we developed a new semi-distributed model LuKARS (Land use change modeling in KARSt systems) that lumps the predominant hydrotopes (i.e. distinct landscape units characterized by homogeneous hydrological properties as a result of similar land use and soil types) present in a catchment as independent, non-linear units. Flows from each hydrotope represent a specific response of the vadose zone (soil-epikarst-infiltration zone) in a defined recharge area. The saturated zone consists of a single linear storage unit recharged by each hydrotope independently. The main goal of this approach was to investigate land use change impacts in a dolomite karst system exploited for the water supply of the city of Waidhofen a.d. Ybbs (Austria) by changing the area covered by each hydrotope. Here, land use changes occured in the form of increasing spaces used for dolomite mining and at the expense of existing forest sites. With our parametrized model, we were able to reproduce the measured discharge in the largest spring of the Waidhofen karst system (Kerschbaum spring). Moreover, we succeeded in transferring the parametrized hydrotopes to other recharge areas (Hinterlug and Mitterlug) and validated the transferability of the modeling approach. Finally, we successfully showed the model’s applicability for land use change impact studies by validating the calibrated model in a period in which the space of the dolomite quarries in the Kerschbaum recharge area almost doubled. The results of our study show that an increase of the dolomite quarries negatively affects the water supply of the city of Waidhofen a.d. Ybbs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Vivek Gupta, Manoj Kumar Jain〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Projected droughts for 21st century over India have been analysed using precipitation and temperature data obtained from Regional Climate Models (RCMs) under Representative Concentration Pathways (RCPs) 4.5 and 8.5. Standardized Precipitation Index (SPI), Standardized effective Precipitation Evapo-Transpiration Index (SP*ETI) and Standardized Precipitation-Evapotranspiration Index (SPEI) at the timescale of 12-months have been used for drought characterization. The K-means clustering algorithm has been utilized to delineate distinct drought homogeneous regions in India. Trends and periodicities in drought characteristics have also been analysed. The results of this study reveal that increase in evapotranspiration due to projected rise in temperature would play a major role in affecting future drought dynamics in most parts of India. Analysis indicates that computed magnitude of drought intensity, duration and frequency depends on the choice of drought indicator. SPEI drought index has been found to project highest drought risk as compared to other two indices used in this study. North India is more vulnerable to increase in drought severity and frequency in near future. However in far future, most parts of the country, except few southeastern states, are likely to face an escalation in drought severity and frequency. A shift in drought hazard from central India toward southeast-central India is likely to happen with increase in greenhouse gas (GHG) concentration. The areal extent of droughts has been found to be increasing historically which is expected to increase further in future for most parts of the country. Historically, drought dynamics were more influenced by decrease in precipitation. However, in future, the drought dynamics will be significantly influenced by increased evapotranspiration resulting from increase in temperature in spite of likely increase in precipitation. The periodicity analysis indicates inter-annual periodicities influencing monsoon months to be distributed uniformly across all clusters of the Indian subcontinent with dominant cycles of 2–3.6 years. Further, change in periodic cycles of drought due to climate change is found to be insignificant.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Lei Xu, Nengcheng Chen, Xiang Zhang, Zeqiang Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The predictability of droughts in China was investigated using a series of statistical, dynamic and hybrid models. The results indicate that, statistical models exhibit better skill in forecasting the Standardized Precipitation Index in six months (SPI6) than dynamic models. Overall, the ensemble streamflow prediction (ESP) method and wavelet machine learning models outperform other statistical models in forecasting SPI6. The hybrid model can improve the performance of SPI6 forecast by combining statistical and dynamic models using Bayesian model averaging (BMA) method. As for drought onset detection, the ‘low probability of detection (POD) low probability of false alarm (POF)’ and ‘high POD high POF’ phenomena exist in statistical and dynamic models, respectively. On average, less than 20% drought onsets can be detected in statistical models while less than 40% in dynamic models, with more than 40% false alarms appearing in statistical models and more than 75% in dynamic models. The hybrid model can slightly balance them, resulting in a POD of 20% and a POF of 50%. In spite of the low predictability, some stations with high equitable threat score (ETS) can be used in early drought warning under certain requirement. These conclusions may help improving drought prediction at a local or national scale.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Sin Zhi Goh, Huiling Guo, Fang Yee Lim, Lai Yoke Lee, Jiangyong Hu, Say Leong Ong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper serves to communicate concerns including misleading presentation of information and the use of incomplete monitoring data in a recent journal article by Lim and Lu (2016) published in the Journal of Hydrology.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Yaohui Cai, Pute Wu, Lin Zhang, Delan Zhu, Shoujun Wu, Xiao Zhao, Junying Chen, Zhen Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Emitter discharge is one of the most important parameters considered in the design, operation, and management of subsurface irrigation systems. The emitter discharge, if properly chosen, can eliminate surface runoff and minimize deep percolation water losses. The discharge from a ceramic emitter depends on the working pressure head and the ceramic hydraulic conductivity, so it is important to determine the optimal working levels for these two design parameters. In this work, it is confirmed that the HYDRUS-2D predictions of the cumulative infiltration and the horizontal wetting front are in good agreement with experimental results, and that the Hydrus-2D model can be used to accurately simulate soil water movement under subsurface irrigation with ceramic emitters. Additional simulations with HYDRUS-2D were used to study the effects of various design parameters (i.e. working pressure head and ceramic hydraulic conductivity) on emitter discharges in soils, deep percolation and soil wetting fronts. Results show that both the working pressure head and ceramic hydraulic conductivity have significant impact on the discharge of emitters in soil, and the deep percolation water losses. The emitter discharge in soil decreases with time and finally stabilizes. When the working pressure head and ceramic hydraulic conductivity are higher, the stable discharge (emitter discharge in soil at 120 h) is greater, and this situation may increase the risk of deep percolation. The relationship between the working pressure head, ceramic hydraulic conductivity, and stable discharge is developed as a power function. To satisfy the water requirements of trees with an active layer of root systems down to about 0–100 cm in the Loess Plateau in China and reduce the risk of deep percolation, it is recommended that the working pressure head should be 20–50 cm of water and the ceramic hydraulic conductivity should be between 0.1 and 1.9 cm h〈sup〉−1〈/sup〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Kelsey R. McDonough, Stacy L. Hutchinson, J.M. Shawn Hutchinson, Jonathan L. Case, Vahid Rahmani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Evaluation of surface soil moisture is necessary to understand spatiotemporal soil moisture trends and their implications on water resources management. This research evaluated a real-time instantiation of NASA’s Land Information System (LIS) for water resources management applications at a higher spatial and temporal resolution than is currently available with remotely-sensed satellite estimates or in situ measurements of the same product. Managed by NASA’s Short-term Prediction Research and Transition (SPoRT) Center, the “SPoRT-LIS” is an observation-driven, real-time simulation of the Noah land surface model at a 3-km resolution over the full continental United States. Surface soil moisture estimates from SPoRT-LIS (0–10 cm layer) were validated against in situ soil moisture from the International Soil Moisture Network in the Missouri and Arkansas-Red-White River Basins. Validation was conducted at in situ measurement depths of 5-cm and 10-cm, and performance was evaluated across varying soil types, land cover, depth, slope, aspect, and pixel heterogeneity to determine conditions under which SPoRT-LIS surface soil moisture had excellent estimation capability. Results demonstrate that 53% of data at a depth of 5-cm and 51% of the data at a depth of 10-cm were significantly correlated with a Spearman’s ρ greater than 0.5 on a daily basis. Based upon validation results, it is evident that the SPoRT-LIS surface soil moisture estimate is satisfactory for research and operational water resources management applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Zachary T. Zambreski, Xiaomao Lin, Robert M. Aiken, Gerard J. Kluitenberg, Roger A. Pielke Sr〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Identification of subregions that share similar historical drought variability provides useful information for drought monitoring, mitigation planning, and resource allocation. This study examined space-time historical drought variability for the Great Plains spanning from 1901 to 2015 by using rotated Empirical Orthogonal Functions (rEOFs). The Standardized Precipitation-Evapotranspiration Index (SPEI) on a three-month timescale was utilized to examine spatial and temporal changes in agricultural drought. We propose a new procedure for identifying the number of rEOFs to be selected for reconstructing subregions. Drought event intensities of moderate, severe, and extreme categories increased in recent years although the number of drought events decreased. Seasonal rEOFs demonstrated that 9–12 subregions were adequate to explain a significant proportion of the original variability in the Great Plains. The time series for each subregion was highly correlated to the original SPEI data and reflected the seasonal meteorological processes that drive drought variability. Several significant wetting trends were found, and there was statistical evidence that drought and wetting event severities had increased for a few subregions. Summer drought has become more variable across space and time, indicating that a more diverse set of resources and strategies might be needed to mitigate impacts of spatially-variable drought and wetting events in coming decades. Winter season drought has become less variable, indicating that perhaps resources could be consolidated when dealing with impacts on a larger scale; however, less variability implies that drought and wetting events may occur across larger regions of the Great Plains during a given season.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): H. Scheepers, J. Wang, T.Y. Gan, C.C. Kuo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Potential impact of climate change on the inland waterway transport of the Mackenzie River Basin (MRB) have been investigated through simulations of the Hydrologiske Byrån avdeling för Vattenbalans (HBV) hydrological model, the HBV-light, for the baseline, 1974–2004, and future periods of 2041–2070 and 2071–2100 over the MRB driven by precipitation and air temperature data of Representative Concentration Pathways, RCP4.5 and RCP8.5 climate scenarios of 10 Global Climate Models statistically downscaled by the Pacific Climate Impacts Consortium using the Bias-Correction Spatial Disaggregation. The average onset of spring snowmelt between 2041 and 2100 is projected to occur up to two weeks earlier than the historical (1974–2004) climate. Projected warmer temperature and higher precipitation will lead to higher runoff for MRB in winter and spring, at the expense of decreased summer streamflow and water level at Fort Simpson and Arctic Red River stations partly because projected increase in evapotranspiration will offset the projected increase in precipitation. Under a warmer climate, navigation issues related to low water levels are expected to increase, e.g., under RCP8.5 at Arctic Red River station, the number of days the water level above 5 m is projected to decrease from 74 days in 1974–2000 to 42 days in the 2080s. The summer durations that water levels of MRB will be at or above 3, 4, and 5 m are projected to decrease by 2.8%–22.2%, 10.0%–34.5%, and 16.2%–43.4%, respectively, which mean navigation problems would increase because safe transit through MRB depends on its water levels.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Sinan Şahin, Martin Ivanov, Murat Türkeş〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The associations between the seasonal moisture budget (precipitation minus evaporation) and atmospheric and oceanic teleconnections related with dry and wet conditions in the greater Mediterranean Basin are investigated. The driest and wettest Mediterranean winters are selected according to the Standardized Precipitation Index (SPI), and the differences in the moisture budget among them and average conditions (i.e. climatology) are investigated. The analysis focuses on the role of major teleconnection indices for the conditions of the driest/wettest winters. According to the results, the Arctic Oscillation (AO) index is the best indicator of variability in the driest/wettest conditions, which are conventionally associated with the North Atlantic Oscillation (NAO). Large-scale climate variability over the Mediterranean Basin is strongly linked with significant changes of the moisture fluxes in the Gulf of Mexico region and partially in the east coast region of the United States (US), especially for wet years in the Western Mediterranean. The displacement of the prevailing atmospheric centres of action located over the subtropical mid-east Atlantic (Azores high) to the Northwest Atlantic determines the wet conditions over the Western and Eastern Mediterranean Basins, respectively. It is speculated that the relative strengths and positions of these large-scale systems control the Eastern and Western patterns of the Mediterranean climate variability.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Giulia Ercolani, Enrico Antonio Chiaradia, Claudio Gandolfi, Fabio Castelli, Daniele Masseroni〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Urbanization modifies the hydrologic cycle, resulting in increased runoff rates, volumes, and peak flows in the drainage network. In this paper, the implementation of green roofs as source control solutions for mitigating the impacts of urbanization is analysed at the urban catchment scale. The hydrologic-hydraulic response of a 2 km〈sup〉2〈/sup〉 urban basin is investigated under various implementation scenarios and rainfall characteristics. In particular, a distributed hydrologic model is employed to assess the impact of 4 spatially homogeneous installations of green roofs (25%, 50%, 75%, 100% of roofs area converted) when forced by 6 storms differing in both duration and return period. In addition, a spatially heterogeneous configuration is tested, with green roofs concentrated where the drainage network is more prone to high degrees of filling. Results show that implementing green roofs at the urban watershed scale can be considered a valuable strategy to reduce both flow peak and volume in urban drainage networks, although the approach is more effective for frequent storms of smaller magnitude. In addition, it is found that the urban system may respond non-linearly to the extent of green roofs implementation in terms of peak flow reduction at the network outlet, and that non-linearity is mainly related to the network being close to its flow convey capability. Finally, planning redevelopment efforts on the basis of local insufficiencies in network convey capacity has the potential of increasing the effectiveness of Low Impact Development solutions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Dongmei Han, Guoliang Cao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Drainage and deformation of intercalated confining layers due to internal stress change (discharge/recharge cycle) in an aquifer-aquitard system not only can have great effects on the groundwater storage (GWS), but also can cause unsynchronized water level (WL) fluctuations. The phase relationship between GWS and WL is crucial for the accuracy and attribution of GWS changes. We identify the dominating episodic components of GWS and WL through the Singular Spectrum Analysis (SSA) analysis and Harmonic analysis. First, we analyzed a generic aquifer-aquitard system using numerical simulations which showed that the dissipation of overpressure from the aquitard and flow from it is the inherent cause of a phase shift between the GWS and WL observations. Water released from confining layers with compaction time constant of zero (no-delay) to century time scale results in detected phase shift between total GWS and WL in the aquifer. Then, we analyzed the complex and varied phase relationship between GWS derived using the Gravity Recovery and Climate Experiment (GRACE) data and measured WL time series in the subsiding North China Plain (NCP) aquifer. The spatially varied phase relationship between GWS and measured WL is reasonably related to varied land subsidence development features and may be related with the compaction time constant and thickness of the confining layers. Results of the generic numerical model and the NCP observations suggest that elastic/inelastic response need to be considered in the interpretation and correction of GWS changes for a compacted aquifer-aquitard system.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): J.P. Martín-Vide, M.C. Llasat〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The 1962 Rubí flood was a severe flash flood, the worst to ever take place in Spain, claiming the lives of more than 800 people following 200 mm of rainfall in 2 h. Such a high number of casualties can be explained by the very high vulnerability of people who lived in the floodplains of a wandering, ephemeral stream (a wadi) prone to flash floods. Many publications to commemorate the 50th anniversary of the flood have been used as proxy data for the event, especially in terms of social aspects. The meteorological and pluviometric information is reviewed, while other information is only found in grey literature. Recently, the event has been considered an outlier in the panorama of European flash floods. Because of the above, this paper aims to convey all the information to readers and show that it deserves to be raised to an international level as an example of an extreme flash flood. After addressing some misunderstandings, it can be concluded that the event was not an outlier, nor was it extreme, in terms of total rainfall, return period, discharge, discharge per unit basin area, unit stream power and flow velocity. It may be extraordinary because the flood reached very high levels by transporting large amounts of both fine and coarse sediment particles. The stream is steep, ephemeral, lacking an armour layer, and prone to torrential events, in which the large sediment transport played a role in how high the flood levels rose. The use of flooding marks to compute discharges is also discussed. In addition, the paper presents a torrential calculation based on the momentum principle in a control volume.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Alejandro García-Gil, Eduardo Garrido Schneider, Miguel Mejías, Damià Barceló, Enric Vázquez-Suñé, Silvia Díaz-Cruz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A steady increase in the consumption of pharmaceuticals and personal-care products worldwide is increasing their occurrence in the biosphere. The current study describes the abundance of 42 selected emerging organic contaminants (EOCs), including human and veterinary antibiotics, UV-filters and analgesics in the groundwater of the urban aquifer of Zaragoza (Spain), which is affected by intensive exploitation of shallow geothermal resources. The presence of groundwater heat pump systems in the aquifer studied offered the opportunity to study the occurrence of EOCs in relation to groundwater temperature and other physicochemical effects derived from this technology. Analysis of the data obtained allowed us to identify statistically significant relationships between the presence of EOCs and temperature, as well as other physicochemical and geochemical properties of groundwater. The results obtained suggest that temperature is a minor factor controlling the degradation of the organic compounds analysed compared to the oxygen input from groundwater heat pump systems which is possibly increasing the aerobic redox conditions, thus preventing the degradation of organic pollutants. Intensive use of shallow geothermal resources therefore seems to contribute in the prevalence of such compounds in the aquifer close to geothermal systems.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418307601-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Nan-Chieh Chao, Jhe-Wei Lee, WeiCheng Lo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉A rigorous mathematical framework is presented for the development of a set of coupled partial differential equations to describe the consolidation of saturated soils under the simultaneous action of external static loads and gravity forces. These equations generalize the Biot model of poroelasticity in a systematic manner to well account for additional momentum exchange arising from the physical mechanisms involved in gravitational compaction due to changes in volumetric fraction and material density of each constituent.〈/p〉 〈p〉A boundary-value problem is then formulated as a representative example to quantitatively examine gravity effect on the dissipation of excess pore fluid pressure and settlement magnitude, and is solved numerically in a finite difference scheme. In the current study, the boundary conditions have been directly calculated in numerical scheme, which improves previous studies to avoid using the approximation of the trapezoidal rule. A physically-consistent parameter, derived fundamentally from the first principle, balance of momentum, is proposed for the first time, which provides an exact measure of the degree to which variations in final total settlement occur due to the presence of gravity effect. This dimensionless parameter takes a closed-form expression that refines our foregoing works, and is quite general since it is applicable to both saturated and variably-saturated soils.〈/p〉 〈p〉Our studies show that the variations are essentially controlled by soil elasticity modulus and height, as well as a derived gravity factor. This factor underlines the importance of the dependency between consolidation behaviors and distinct physical properties of pore fluids. Lastly, a comparative study is carried out, indicating that gravity forces yield more significant impact on unsaturated soils than saturated soils we examined, leading to more relative increment in the final total settlement.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Xiaojun Deng, Youpeng Xu, Longfei Han, Song Song, Guanglai Xu, Jie Xiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The longitudinal functional connectivity of river systems refers to the process-based connections between upstream and downstream areas and is fundamental to understanding the dynamic and nonlinear hydrological behaviour of river basins. However, the quantification of such connectivity remains a challenge due to the absence of a consensus on the appropriate data and methods, especially in delta plains. In this study, based on the difference between water level fluctuations at adjacent stations, a new and quantitative longitudinal functional connectivity index (LFCI) was developed for delta plains. Focusing on the Taihu Plain, we then analysed the spatial-temporal changes in the LFCI during 1960–2012 and investigated the correlations between the LFCI and climate change and human activities. We found that the decadal, annual and seasonal changes in the average LFCI all presented slightly increasing trends in the recent 50 period, but the annual average LFCI increased significantly after 1978; the average LFCIs in June, July, and August of the flood season were less than those in other months in the Taihu Plain. We also found that the spatial-temporal changes in the average LFCI exhibited larger differences at the subregional and station scales; those in the Wu-Cheng-Xi-Yu subregion were least, and the average LFCIs at stations near the borders of adjacent subregions were less than those at other stations. Moreover, we found that the average LFCI had significant correlations with precipitation, river density and water surface ratio. Our results were consistent with common sense facts, which demonstrated that the indicator developed in this study can quite effectively quantify the longitudinal functional connectivity of river systems in delta plains.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Shunping Xie, Jinkang Du, Xiaobing Zhou, Xueliang Zhang, Xuezhi Feng, Wenlong Zheng, Zhiguang Li, Chong-Yu Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉To capture the temporal variability of parameters of hydrological models, the segmented optimization algorithm (SOA) is usually used which subdivides the calibration period into a number of sub-periods and seeks optimal parameters for each sub-period by optimizing the objective function based on the measured and estimated data in the same sub-period. In this paper, we developed a new method that is called a progressive segmented optimization algorithm (PSOA), which seeks optimal parameters by optimizing the objective function based on both the current and all the prior sub-periods.〈/p〉 〈p〉We applied and compared the SOA and PSOA algorithms to the Snowmelt Runoff Model (SRM) in simulating snow-melt streamflow for the Manasi River basin, northwest of China, during snowmelt seasons of 2001–2012. The study showed: (1) PSOA can effectively calibrate the time-variant model parameters while avoiding too much computational time caused by a significant increase of parameter dimensionality. (2) PSOA outperforms SOA for both single-snowmelt-season and multi-snowmelt-season simulations. (3) For single-snowmelt-season simulation, the length of the sub-period has an apparent effect on model performance, the shorter the sub-period is, the better the model performance will be, when the model is calibrated using the PSOA method. (4) For multi-snowmelt-season simulation, an over-short sub-period may cause overfitting problems in some cases such as the situation of taking Nash-Sutcliffe efficiency (NSE) as the objective function. A compromised length of sub-period and objective function may have to be chosen as a trade-off among evaluation criteria and between the importance of calibration and validation.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): P. Yeste, J. Dorador, W. Martin-Rosales, E. Molero, M.J. Esteban-Parra, F.J. Rueda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Monthly streamflow records from a set of gauging stations, selected to form a reference hydrologic network, are analyzed together with precipitation and temperature data to establish whether the streamflows in the Guadalquivir River Basin have experienced changes during the last half of the 20th century that can be attributed to hydrological forcing. The observed seasonal and annual streamflows in the reference network have undergone generalized and significant decreases during the study period. Annual rainfall did not experienced statistically significant changes. The observed trends in streamflows may be attributed to either land-use changes, or to the statistically significant changes exhibited both by yearly potential evapotranspiration values and by the seasonal redistribution of precipitation. In the attribution work conducted using both data-based and simulation-based methods, the intra-annual redistribution of precipitation is shown to be the main statistically significant climate-driver of streamflow change. The contributions of other non-climate factors, such as changes in land cover, to the reduction in annual streamflows are shown to be minor in comparison.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): M. Beyer, J.T. Hamutoko, H. Wanke, M. Gaj, P. Koeniger〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Knowledge on the water uptake depths of vegetation is crucial for understanding water transport processes of the soil-vegetation atmosphere continuum and relevant for many applications (e.g. the estimation of groundwater recharge, irrigation planning and the parameterization of (eco-) hydrological models). The identification and quantification of water uptake from deep soil layers and groundwater remain challenging. This study uses a combined framework based on natural abundances of stable water isotopes and isotopic labeling experiments with deuterium oxide (〈sup〉2〈/sup〉H〈sub〉2〈/sub〉O) to study root water uptake and identify uptake from deep soil in a semi-arid environment.〈/p〉 〈p〉Between 2013 and 2016, more than 1000 soil (isotope depth profiles); plant (xylem and transpiration) and water (precipitation and groundwater) samples for the analysis of isotope ratios were collected. Two experiments using isotopic labeling were carried out in order to assess root water uptake depths. Herein, we i) present series of deep soil water isotope depth profiles, interpret water transport dynamics and ecohydrological feedbacks; ii) examine the suitability of natural isotope depth profiles for identifying deep root water uptake; iii) apply the Bayesian mixing model MixSIAR to quantify deep root water uptake and iv) constrain water uptake depths using isotopic labeling experiments and derive an active root water uptake distribution.〈/p〉 〈p〉Our results show that the form of isotope depth profiles of soil in water-limited environments follows characteristic shapes for the end of the rainy and dry seasons, respectively. Isotope ratios in the upper 4 m of the soil are heavily dependent on the character of the respective rainy season. Under certain conditions – e.g. droughts or weak rainy seasons – the isotope depth profile displays an enrichment in heavy isotopes up to 4 m depth. Such pronounced anomalies provide an opportunity for studies on source water partitioning. In the present experiment, the studied individuals of 〈em〉Acacia erioloba〈/em〉 were found to obtain 37% [24–52%] of their water from deep soil (〉4 m) and groundwater at the end of the dry season of 2015. All other investigated trees (individuals of 〈em〉B. plurijuga, S. luebertii, T. sericea〈/em〉 and 〈em〉C. collinum〈/em〉) mainly utilize water originating from 1 m to 2.5 m depth. Under “average” rainy season conditions, the similarity of isotope ratios of potential plant water sources hinders a conclusive identification of water uptake depths.〈/p〉 〈p〉Deep natural isotope depth profiles in dry environments can – under certain conditions – be used to identify and quantify access of vegetation to deep water resources. Isotopic labeling enables to determine active root distributions for the lateral root zone. Combined frameworks contribute to a better understanding of deep water uptake. A differentiated consideration of water uptake from the lateral root zone and deep, potentially groundwater-tapping roots is required in order to fully investigate ecohydrological feedbacks and for a proper parameterization of models.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Damjan Ivetić, Dušan Prodanović, Luka Stojadinović〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Flow monitoring in Urban Drainage Systems (UDS) is required for a successful system control and operational assessment. Commonly used methods can lead to erroneous results in partially filled pipes and hostile environmental conditions, normally encountered in UDS. Recent studies focused on the flow rate measurements in UDS revealed that the capability of acoustic Doppler velocimeters to estimate mean flow velocity is impeded by several factors. Most prominent issues are the operation under low flow depths and velocities, as well as in the case of the sedimentation at low flow velocities. This study is focused on an alternative method for the velocity measurements in the UDS, based on Electro-Magnetic Velocity (EMV) meters. The study also determines the sensor’s capacity to operate when covered by a porous sediment layer, using a newly developed procedure. A brief theoretical background is given to support the idea behind the usage of EMV in UDS. Measurement uncertainties were firstly benchmarked in the laboratory flume without sediment. After local, site-specific (re)calibration, EMV operated with combined uncertainty of only few cm/s. Furthermore, the EMV measured the flow rates with depths low as 4 cm and velocities bellow 5 cm/s. Additionally, a series of tests were performed with sediment layers above the EMV meter, varying in height from 0 to 80 mm. Observational uncertainty analysis showed that EMV meter can be used even in these conditions. Since the bias uncertainty increased with the rise of the sediment depth, a correction function model was derived for the transformation of the output signal, reducing the observational uncertainties below 5 cm/s. Subsequently, practical implications of the EMV usage in the UDS are considered.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Richard Arsenault, François Brissette, Jean-Luc Martel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper investigates the issues related to the use of validation in hydrological model calibration. Traditionally, models are calibrated and then assessed on an independent period (split-sample) to determine their adequacy in simulating streamflow as compared to observations. In this study, two hydrological models and three North American catchments are used to evaluate the effects of using validation to assess the model parameters’ robustness on the model’s actual simulation capabilities and accuracy in simulating streamflow. The length of the calibration period is increased from 1 to 16 years, and for each case a large number of randomly selected combinations of years are used for calibration and for validation using the Nash-Sutcliffe Efficiency metric. The calibrated model is then run on an independent 8-year test-period to assess the model’s actual performance in simulation mode in unknown conditions. The process is bootstrapped 30 times to ensure the robustness of the results. The tests pit the calibration/validation methods on increasing calibration period lengths against a full calibration on the entire available dataset. Results show that the calibration on the full dataset is the optimal strategy as it generates the most robust parameter sets, provides the best model accuracy on an independent testing period and does not require assumption-making on the modeler’s part. The calibrated parameter sets for each test-case were evaluated using the relative bias and correlation metrics, which revealed that the method transfers well to these two other metrics. Results also demonstrate the pitfalls of the commonly used split-sampling strategy, where good parameter sets may be discarded due to model performance discrepancies between calibration and validation periods. The conclusions point to the need to use as many years as possible in the calibration step and to entirely disregard the validation aspect under certain conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Jiabo Yin, Shenglian Guo, Shaokun He, Jiali Guo, Xingjun Hong, Zhangjun Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Climate change will lead to great impacts on flood frequency curve and design floods in the future. However, traditional hydrologic approaches often fail to analyze the flood characteristics within a bivariate framework under changing environment. Moreover, previous studies investigating bivariate characteristics of flood usually do not derive the adaptive flood quantiles. This study assesses the implications of climate change for future bivariate quantiles of flood peak and volume in Ganjiang River basin, China. The outputs of two global climate models (BNU-ESM and BCC-CSM1.1) are statistically downscaled by Daily bias correction (DBC) method and used as inputs of the Xinanjiang hydrological model to simulate streamflow during 1966–2099. Projections for future flood (2020–2099) under Representative Concentration Pathway (RCP) 8.5 scenario are divided into two 40-year horizons (2040s, 2080s) and a comparison is made between these time horizons and the baseline (1966–2005). Univariate flood frequency analysis indicates that there is a considerable increase in the magnitude and frequency of flood under the RCP8.5 scenario, especially for the higher return periods. The bivariate quantile curves under different levels of Joint Return Period (JRP) for historical and future periods are derived by copula functions and the most likely realizations are estimated. It is found that climate change has heavier impacts on the future joint bivariate quantiles for larger return periods. Finally the adaptive isolines and most likely flood quantiles under a JRP are derived from analyzing the merged series by non-stationary copula-based models. The results highlight that the joint probability, illustrated by the isoline of a given JRP, varies significantly over time when non-stationary models are applied. This study incorporates the impacts of climate change on bivariate flood quantiles and develops an adaptive quantile estimation approach, which may provide useful information for the references of flood risk assessment and management under changing environment.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Mohammad Ebrahim Banihabib, Bahman Vaziri, Saman Javadi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, a model is proposed for the assessment of the effectiveness of various mulches in increasing deep percolation of rainfalls for enhancing arid zones aquifers. For this purpose, 8 precipitations were selected from the Intensity-Duration-Frequency (IDF) curves of the study area with a return period of 2 and 5 years. The deep percolation of these precipitations were examined in lysimeters with gravel, sand and mixed mulches and without any mulch. Then 192 data of soil moisture, daily maximum air-temperature and deep percolation were measured for driving empirical equations. Moreover, the efficiency and accuracy of these empirical equations were investigated using Coefficient of Determination (CD) and Nash–Sutcliffe Efficiency Coefficient (NSEC). The results showed that the obtained empirical equations could estimate deep percolation and evaporation with an acceptable accuracy. Using these equations and the soil-water balance equation, a soil moisture model was developed for the assessment of deep percolation. Then it was examined to evaluate the efficiency of the mulched soils in increasing soil moisture and aquifer recharging of three years’ precipitations in Shahrekord plain, Iran. The results showed that the deep percolation increased in all examined mulched soils compared to unmulched soil, its maximum and cumulative increase were in gravel mulch with 21.3% and 30%, respectively. Furthermore, groundwater modeling results showed that the mulching could improve groundwater level as 0.34 m over a three year period. Finally, this paper proposes soil mulching for enhancing groundwater resources and a model to assess it.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Scott C. James, Lichun Wang, Constantinos V. Chrysikopoulos〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A particle-tracking algorithm was developed to simulate colloid transport subject to wall effects on diffusion as well as colloid surface attachment as described by DLVO kinetics. The effects of spatially variable fracture surface potential, which contributed to spatially variable attachment strength affecting colloid transport, were investigated. The fracture surface potential was assumed to be either positively, neutrally (zero), or negatively correlated with the lognormally distributed local fracture aperture, described with a mean, variance, and isotropic correlation length. The results from several model simulations indicated that wall effects were negligible for the synthetic fractures studied here. When fracture surface potential was negatively correlated with local aperture, colloids were preferentially transported through the fracture, because they tended to enter high-flow, large-aperture regions where they underwent less attachment (have the largest first moment measured upon exit of the first colloid from the fracture). The variance (second moment) increased for flowing colloids when comparing negatively to zero and then positively correlated surface potentials to fracture apertures, because spreading notably increased when suspended colloids were temporarily attached onto fracture surfaces. For colloids attached onto fracture surfaces, both first and second moments decreased from negatively, to neutrally (zero), to positively correlated surface potentials to apertures. This is an intuitive result, consistent with fewer colloids attaching along the larger aperture preferential flow paths.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Claudia Feijoó, María Laura Messetta, Cecilia Hegoburu, Alicia Gómez Vázquez, José Guerra-López, Josep Mas-Pla, Laura Rigacci, Victoria García, Andrea Butturini〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The relevance of fluvial systems to process nutrients and carbon is widely accepted, but their role as sinks and sources of nutrients and dissolved organic carbon (DOC) is still under discussion especially in non-forested and highly productive streams. In this study, we used a mass balance approach at a reach scale in a Pampean stream to elucidate the major sources of water, nutrients and DOC as well as to determine net in-stream retention efficiencies of nutrients and DOC under different hydrological conditions.〈/p〉 〈p〉We measured conductivity, conservative ions (chloride and calcium), soluble reactive phosphorus (SRP), nitrate (NO〈sub〉3〈/sub〉), nitrite (NO〈sub〉2〈/sub〉), ammonium (NH〈sub〉4〈/sub〉) and DOC at the end-point of a reach of Las Flores stream (site A), at two upstream tributaries (B1 and B2), and at each potential hydrological contributors to stream flow (groundwater, overland and subsurface flows, and rainfall). In addition, we monitored one storm event where we collected samples during the rising and the recession limb of the hydrograph.〈/p〉 〈p〉Stream flow originated from groundwater (≈50%), upstream tributaries (B1 and B2) at baseflow, whereas overland flow contributed 〉20% during high flows. During baseflow, groundwater provided NO〈sub〉3〈/sub〉 to stream water, while B2, which received a point input of a dairy industry, was the main source of SRP and NH〈sub〉4〈/sub〉. Conversely, SRP and NH〈sub〉4〈/sub〉 were provided by B1, overland flow and subsurface flow during high flows. Overland flow also contributed DOC during high flow periods. Mass balance estimates revealed that the reach acts as a source of DOC, SRP and NO〈sub〉3〈/sub〉 (21.4, 37.4 and 53.5% mean net in-stream release, respectively) and a sink of NH〈sub〉4〈/sub〉 (−36.8% mean net in-stream retention). Relevant in-stream processes may be nutrient uptake (as in the case of SRP and NH〈sub〉4〈/sub〉) and biotic production (DOC), as well as decomposition (SRP) and nitrification (NH〈sub〉4〈/sub〉) in this Pampean stream. Our results stress the relevance of nutrient and DOC generation processes within the channel in non-forested and highly productive streams.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418307455-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 567〈/p〉 〈p〉Author(s): Yunliang Li, Qi Zhang, Rui Ye, Jing Yao, Zhiqiang Tan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thermal regime and its response to meteorological and hydrological forcings play an important role in controlling water quality and ecosystem of lakes. Many large floodplain lakes are subjected to significant river-lake interactions and could benefit greatly from hydrodynamic modeling. The current work presents a first attempt to use a 3D hydrodynamic model and statistical methods to explore spatiotemporal variations and primary causal factors of thermal stability within a large river-lake-floodplain system (Poyang Lake, China). The hydrodynamic model successfully reproduced the lake hydrodynamics and thermal dynamics through a comparative analysis of field measurements. Simulation results revealed that the thermal stability of Poyang Lake exhibits similar spatial patterns between seasons; however, the lake is generally stratified during summer and early autumn. It is classified as partial mixed and full mixed during winter and spring. The thermal stratification may develop in the center area and eastern bay area of the lake, while the full mixing is likely to occur in the floodplains and the main flow channels. Statistics and simulations indicate that the air temperature, solar radiation and evaporation trigger a positive effect on the thermal stability of Poyang Lake, whereas a negative relationship is recognized due to the catchment river temperature. The responses of thermal stability to the meteorological and hydrological changes are much stronger in summer than other seasons, producing a significant seasonal thermal regime in the floodplain lake. Additionally, the dynamics in the lake water depth and associated hydrological regime are a major factor in maintaining the seasonal thermal stability of Poyang Lake. The findings of this study can support management of Poyang Lake as well as other similar floodplain lakes, by providing information on both water quality and ecosystem succession.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0022169418307686-ga1.jpg" width="373" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Liguang Li, Zhenli He, Michael R. Shields, Thomas S. Bianchi, Andrea Pain, Peter J. Stoffella〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sediment and nutrient fluxes from agricultural areas to rivers have led to high dissolved organic nitrogen (DON) concentrations that promote algal blooms. Few studies have been conducted to evaluate the effect of sediments on aquatic nitrogen, especially DON, on such blooms. Here, concentrations of dissolved inorganic nitrogen, DON, urea, free amino acids (DFAA), combined amino acids (DCAA), excitation-emission matrices (EEMs) were simultaneously determined in both sediments and the overlying waters from three different waterways and their interactions were analyzed, together with sediment enzyme activities, in the agriculture dominant St. Lucie Watershed. Concentrations of DCAA were generally higher, as compared to DFAA regardless of medium. The sum of urea and amino acids accounted for ∼20% of water DON. The composition of DCAA and DFAA varied between water and sediment. Degradation index of both DFAA and DCAA was similar between sediment and water, suggesting strong exchange activities between water and sediment. Sediment NH〈sub〉4〈/sub〉-N concentration was associated closely with 14 water DFAA. A model, comprised of sediment DON, NH〈sub〉4〈/sub〉-N, activities of acid phosphatase (AP) and leucine aminopeptidase (LAP), and two fluorescence compounds, can predict the variations of water NH〈sub〉4〈/sub〉-N (55%), NO〈sub〉3〈/sub〉-N (77%), DOC (83%), DON (64%), DFAA (〉88%), DCAA (62–96%), and fluorescence indexes (98%). While this model provided an accurate prediction of water nutrient status in the St. Lucie Watershed, it still needs to be verified in situ across larger environmental gradients to incorporate real-world complexity and increase generality.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology, Volume 566〈/p〉 〈p〉Author(s): Wondwosen M. Seyoum〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Climate variability along with increase in the demand for water resources highlights the need for better understanding of the link between regional climate and terrestrial water storage. This paper examined the variation of terrestrial water storage in relation to climatic influences over the Upper Blue Nile (UBN) River Basin from GRACE Terrestrial Water Storage Anomaly (TWSA), satellite altimetry, rainfall, and Multivariate El Niño-Southern Oscillation Index (MEI) anomaly data. Although there is no statistically significant (α = 0.05) long-term trend in terrestrial water variation and rainfall in the basin (lake storage, TWSA, and rainfall, p-value = 0.45, 0.48, and 0.55, respectively), in the last decade, two visible droughts occurred between 2002 and 2004, and 2009 and 2010, which resulted in water deficit in the basin, where below average rainfall, TWSA, and lake height (storage) were observed during these periods. Extreme rainfall analysis from Standardized Precipitation Index (SPI) and strong connection between wet season rainfall, lake height, and TWSA, respectively, indicate interannual terrestrial water storage dynamics in the UBN Basin is strongly influenced by climate. Further, the El Niño-Southern Oscillation (ENSO) influences rainfall in the UBN Basin, specifically the peak rainfall season (June-September), which shows negative correlation (r = −0.62) with MEI anomaly values, which indicates that the El Niño case (positive MEI values) is linked to the dry conditions in the basin. The findings of this study, combined with studies such as socioeconomic impact of drought, will facilitate better planning and management of water resources in water stressed regions. Furthermore, this study demonstrates the application of a combination of satellite and other hydrologic data in understanding the hydro-climatic condition of a remote basin.〈/p〉〈/div〉 〈/div〉