ALBERT

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Alberto Pistocchi, Costanza Calzolari, Francesco Malucelli, Fabrizio Ungaro Study region The plains of Emilia Romagna, Italy. Study focus Urban expansion is among the main causes of increase in flood frequency and intensity in small rural catchments in Europe, and our study region is paradigmatic in this respect. We present here a regional screening-level assessment of soil sealing impacts in terms of increased flood peak discharges and flooding volumes on the secondary drainage network of the plains. We estimate flood peak discharges and flooding volumes through a simple kinematic model with runoff coefficients for the land use of 2008 and 1976. Additionally, we calculate an equivalent compensatory flood detention volume that would enable preserving flood peak discharges as prior to soil sealing (principle of “hydraulic invariance”). The proposed approach is simple and readily applicable to any region facing similar issues, for screening-level assessment of flood hazards over an extended stream network. New hydrological insights for the region The analysis highlights a significant increase in flood hazards throughout the secondary stream network. The impact. Widespread and relatively uniform, is more apparent in smaller catchments and in the case of more permeable soils. This demands retrofitting of the majority of the drainage network and/or significantly higher costs from flooding damages. The analysis suggests that costs of additional flooding after soil sealing may be higher than those of soil sealing impacts compensation through flood detention (hydraulic invariance).

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): M.A. Sarr, O. Seidou, Y. Tramblay, S. El Adlouni Study region The study considers six precipitation stations located in Senegal, West Africa. Senegal is located in the Sahel, an area that is threatened by climate variability and change. Both droughts and extreme rainfall have been an issue in recent years. Study focus Two different statistical downscaling techniques were applied to the outputs of four regional climate models at six selected precipitation stations in Senegal. First, the delta-change method was applied to the mean annual precipitation as well as the 5, 10, 20, 50 and 100-year return period daily precipitation events. Second, a quantile–quantile transformation (QQ) was used to downscale the monthly distributions of precipitation simulated by regional climate models (RCMs). The 5, 10, 20, 50 and 100-year daily precipitation events were afterward calculated. All extreme events were calculated assuming that maximum annual daily precipitations follow the generalized extreme value (GEV) distribution. The two-sided Kolmogorov–Smirnov (KS) test was finally used to assess the performance of the quantile–quantile transformation as well as the GEV distribution fit for the annual maximum daily precipitation. New hydrological insights for the region Results show that the two downscaling techniques generally agree on the direction of the change when applied to the outputs of same RCM, but some cases lead to very different projections of the direction and magnitude of the change. Projected changes indicate a decline in mean precipitation except for one RCM over one region in Senegal. Projected changes in extreme precipitations are not consistent across stations and return periods. The choice of the downscaling technique has more effect on the estimation of extreme daily precipitations of return period equal or greater than ten years than the choice of the climate models.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): J.S. Lessels, T.F.A. Bishop Study region South eastern Australia. Study focus This region is characterised with rainfall events that are associated with large exports of nutrients and sediments. Many water quality monitoring schemes use a form of event-based sampling to quantify these exports. Previous water quality studies that have evaluated different sampling schemes often rely on continuously monitored water quality data. However, many catchment authorities only have access to limited historical data which consists of event-based and monthly routine samples. Therefore there is a need to develop a method that assesses the importance of sampling events using information from limited historical data. This work presents a simulation based approach using unconditional simulation based on historical stream discharge. Such an approach offers site-specific information on optimal sampling schemes. A linear mixed model is used to model the relationship between total phosphorus and stream discharge and the auto-correlation of total phosphorus. New hydrological insights for the region The inclusion of event-based sampling improved annual load estimates of all sites with a maximum RMSE difference of 16.11 tonnes between event-based and routine sampling. Based on the accuracy of annual loads, event-based sampling was found to be more important in catchments with a large relief and high annual rainfall in this region. Using this approach, different sampling schemes can be compared based on limited historical data.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Hayet Chihi, Ghislain de Marsily, Habib Belayouni, Houcine Yahyaoui Study region “Jeffara de Medenine” aquifer system in south-eastern Tunisia. Study focus This study investigates the role of fault structures in the distribution of hydrogeochemical facies and groundwater compartmentalization for the aquifer system. New hydrological insights for the region The proposed methodology, including seismic structural study, hierarchical cluster analysis and geostatistical methods, allowed an efficient multi-element characterization of the spatial patterns of the structural elements in the aquifers and of the hydrogeological parameters used in a spatial cross-correlation to explore the dependence of the geochemical properties in each “geochemical population” on the hosting structural compartment to delineate the different geochemical compartments. The tectonic studies showed that the lateral extent of the aquifers is controlled by normal faults. The multivariate statistical analysis revealed a strong spatial coherence between hydrogeochemical facies clustering and the reservoir compartments at both large and small scales. The kriged maps of major-ion concentrations and of total dissolved solids in the aquifers were then analyzed and compared with the reservoir facies distribution for each compartment, the geometric characteristics of the aquifer, and the piezometric level trends. This allowed to characterize the hydraulic behavior of the Medenine fault and to understand the underlying physical and chemical processes having led to the spatial distribution of the geochemical properties, and thus, the hydrogeochemical functioning of the aquifers.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Marnie L. Atkins, Isaac R. Santos, Damien T. Maher Study region This study investigates dissolved methane distribution in groundwater from the Richmond River Catchment (New South Wales, Australia) before proposed coal seam gas (CSG, or coal bed methane) development. Study focus Unconventional gas exploration has rapidly expanded in recent years. However, the impact of these operations on groundwater systems is poorly understood. A total of 91 groundwater samples were analyzed from 6 geological units. Our observations act as regional baseline research prior to CSG extraction and may assist with long term impact assessment. New hydrological insights for the region Methane was found in all geological units ranging between 0.26 and 4427 μg L −1 (median 10.68 μg L −1 ). Median methane concentrations were highest in chloride-type groundwater (13.26 μg L −1 , n = 58) while bicarbonate-type groundwater had lower concentrations (3.71 μg L −1 ). Groundwater from alluvial sediments had significantly higher median methane concentrations (91.46 μg L −1 ) than groundwater from both the basalt aquifers (0.7 μg L −1 ) and bedrock aquifers (4.63 μg L −1 ); indicating geology was a major driver of methane distribution. Methane carbon stable isotope ratios ranged from –90.9‰ to –29.5‰, suggesting a biogenic origin with some methane oxidation. No significant correlations were observed between methane concentrations and redox indicators (nitrate, manganese, iron and sulphate) except between iron and methane in the Lismore Basalt ( r 2 = 0.66, p 〈 0.001), implying redox conditions were not the main predictor of methane distribution.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Z. Zomlot, B. Verbeiren, M. Huysmans, O. Batelaan Study focus Groundwater is of strategic importance. The accurate estimation of groundwater recharge and assessing the fundamental controlling factors are therefore of utmost importance to protect groundwater systems. We used the spatially-distributed water-balance model WetSpass to estimate long-term average recharge in Flanders. We validated recharge rates with base flow estimates of 67 daily stream flow records using the hydrograph analyses. To this end we performed principal component analysis, multiple linear regression analysis and relative importance analysis to assess the controlling factors of the spatial variation of recharge and base flow with the influencing watershed characteristics. New hydrological insights for the region The average resulting recharge is 235 mm/year and occurs mainly in winter. The overall moderate correlation between base flow estimates and modeled recharge rates indicates that base flow is a reasonable proxy of recharge. Groundwater recharge variation was explained in order of importance by precipitation, soil texture and vegetation cover; while base flow variation was strongly controlled by vegetation cover and groundwater depth. The results of this study highlight the important role of spatial variables in estimation of recharge and base flow. In addition, the prominent role of vegetation makes clear the potential importance of land-use changes on recharge and hence the need to include a proper strategy for land-use change in sustainable management of groundwater resources.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): B. Ibrahim, D. Wisser, B. Barry, T. Fowe, A. Aduna Study region Hydrological observation networks in the West African region are not dense and reliable. Furthermore, the few available discharge data often present significant gaps. The Volta basin, the second largest transboundary basin in the region, is a typical example of a basin with inadequate hydrological networks. Study focus In this study, a prediction approach to determine monthly discharge in ungauged watersheds is developed. The approach is based on the calibration of two conceptual models for gauged watersheds and an estimation of models’ parameters from the physical and climatic characteristics of the watersheds. The models’ parameters were determined for each ungauged watershed through two different methods: the multiple linear regressions and the kriging method. The two methods were first validated on five gauged watersheds and then applied to the three ungauged watersheds. New hydrological insights for the region The application of the two hydrological models on the eight watersheds helped to produce relevant monthly runoff and to establish the annual hydrological balances from 1970 to 2000 for both gauged and ungauged watersheds. The developed method in this study could therefore help estimate runoff time series, which are of crucial importance when it comes to design hydraulic structures such as small reservoirs.

Description: Publication date: Available online 14 August 2015 Source: Journal of Hydrology: Regional Studies Author(s): Mayank Shekhar, Amalava Bhattacharyya Study region Zemu Chuu (river), Lachen, North Sikkim, Eastern Himalaya India. Study focus Using tree-ring data of fir ( Abies densa ) the temporal variation of 222 years January–April mean discharge of Zemu Chuu, upper reaches of the Teesta River at Lachen, North Sikkim Eastern Himalaya was investigated. This was based on linear regression reconstruction model which explained variance of 50.1% during calibration period (AD 1976–1996). The model was verified by reduction of error (RE), sign test (ST), product mean test (Pmt), root mean square error (RMSE) and Durbin–Watson test (DW). The RE never falls below zero suggesting the model had explanatory power over the entire period of reconstruction. New hydrological insights for the region The explored strong relationship between tree ring records and instrumental data enable to develop mean January–April months (premonsoon) river discharge of Zemu Chuu from remote area of Sikkim. Reconstructed data reveals high stream-flow when it is more than the mean plus one standard deviation and as low when flow is less than the mean minus one standard deviation. There were such 23 high discharge and 21 extremely low years over the past AD 1775–1996. This premonsoon reconstruction of river flow would be of great significance when scarcity of water is acute in the North East Himalaya.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Jonathan A. Warrick, John M. Melack, Blair M. Goodridge Study region Coastal watersheds of southern California, United States. Study focus We sought to better understand the rates and variability of suspended-sediment discharge from small coastal watersheds (〈100 km 2 ) of California. Suspended-sediment concentrations and stream discharge were measured with automated samplers near the mouths of four small watersheds (10–56 km 2 ). New hydrological insights for the region The watersheds were found to have suspended-sediment concentrations that extended over five orders of magnitude (1 to over 100,000 mg L −1 ). Sediment concentrations were weakly correlated with discharge ( r 2 = 0.10–0.25), and four types of hysteresis patterns were observed during high flow events (clockwise, counterclockwise, no hysteresis, and complex). Annual sediment yields varied by 400-fold across the four watersheds (e.g., 5–2100 t km −2 yr −1 during the 2003–2006 water years), and sediment discharge was measurably elevated in one watershed that was partially burned by a late summer wildfire. Dozens of high flow events provided evidence that suspended-sediment yields were generally related to peak stream discharge and event-based precipitation, although these relationships were not consistent across the watersheds. This suggests that watersheds smaller than 100 km 2 can provide large – and therefore important – fluxes of sediment to the coast, but that simple techniques to estimate sediment loads, such as sediment rating curves, hydrologic regressions, and extrapolation using global sediment yield relationships that include watershed area as a primary factor, may provide poor results. Graphical abstract

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Chris C. Gianfagna, Chris E. Johnson, David G. Chandler, Charlie Hofmann Study region The Catskills region of New York State is largely forested and dominated hydrologically by stream watersheds with few natural lakes. The area experiences intensive water resources management and ecosystem monitoring due to its strategic role as the principal water supply for New York City. Study focus We analyzed average daily flows in nested and non-nested pairs of gaged watersheds in the Catskills to assess whether daily flow in ungaged watersheds can be calculated based on watershed area ratios. New hydrological insights for the region Watershed area ratio was the most important basin parameter for estimating flow at upstream sites based on downstream flow. The area ratio alone explained 93% of the variance in the slopes of relationships between upstream and downstream flows. Regression analysis indicated that flow at any upstream point can be estimated by multiplying the flow at a downstream reference gage by the watershed area ratio. This method accurately predicted upstream flows at area ratios as low as 0.005. We also observed a very strong relationship ( R 2 = 0.79) between area ratio and flow–flow slopes in non-nested catchments. Our results indicate that a simple flow estimation method based on watershed area ratios is justifiable, and indeed preferred, for the estimation of daily streamflow in ungaged watersheds in the Catskills region.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Alfonso Rivera Study region Canada–USA border. Study focus Since 2005, Canada has followed international developments in transboundary groundwater issues in cooperation with its southern neighbor the United States (USA) within the Internationally Shared Aquifer Resources Management Initiative (ISARM) of UNESCO. As a result, 10 Transboundary Aquifer Systems (TAS) were identified along the border between Canada and the USA. This study is an extensive review of the current state of the 10 TAS. Documentation of scientifically-based knowledge on TAS is an important step in identifying potential issues in policies that might be adopted to address shared water-resource issues. New hydrological insights for the region This analysis emphasizes the need for more scientific data, widespread education and training, and a more clearly defined governments’ role to manage groundwater at the international level. The study reviews the current legal framework and summarises the current scientific knowledge for the TAS with respect to the hydrologic and geologic framework as well as some of the major drivers for supply and demand. It also describes the links, approach and relevance of studies on the TAS to the UN Law of Transboundary Aquifers and on how these might fit in the regional strategy for the assessment and management of the TAS. Clear communication, shared knowledge and common objectives in the management of TAS will prepare the countries for future negotiations and cooperative binational programs.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Brioch Hemmings, Daren Gooddy, Fiona Whitaker, W. George Darling, Alia Jasim, Joachim Gottsmann Study region Montserrat, Lesser Antilles, Caribbean. Study focus Analysis of δ 2 H and δ 18 O isotopes, and chlorofluorocarbon (CFC) anthropogenic tracers in Montserrat groundwater provides insights into the age and provenance of the spring waters. New hydrological insights δ 2 H and δ 18 O analysis indicates uniform recharge elevations for groundwaters on Montserrat. CFC-11 and CFC-12 analysis reveals age differences between isotopically similar, high elevation springs and low elevation aquifer waters. Low CFC concentrations within a confined low elevation aquifer suggest water ages of ∼45 years. High CFC concentrations in the northern and western springs are explained by rapid infiltration of cool (high CFC concentration) rainfall into saturated compartments, with flow through the vadose zone to the phreatic zone dominated by compartment flow. Lower CFC concentrations in a number of aligned warmer springs suggest a contribution from older, warmer waters from depth. Temperatures and CFC concentrations indicate older component supply rates of up to 8 L/s to the highest yielding spring on Centre Hills, with contributions of up to 75% in the warmest spring waters.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: Available online 3 April 2015 Source: Journal of Hydrology: Regional Studies Author(s): A. Shahul Hameed , T.R. Resmi , S. Suraj , C. Unnikrishnan Warrier , M. Sudheesh , R.D. Deshpande Study region The Chaliyar river basin, Kerala State, India. Study focus Detailed understanding about spatio-temporal variation in the interaction and exchange of water between surface and sub-surface reservoirs is important for effective watershed management. Spatio-temporal variations in the oxygen isotopic composition ( δ 18 O) were used to understand the interaction between groundwater and river water, and to estimate the groundwater recharge from river water in the Chaliyar river basin. New hydrological insights for the region Based on the spatio-temporal variation in δ 18 O values of river and groundwater and fluctuation in ground water levels, following important inferences are made: (1) estimated river water contribution to post-monsoon groundwater recharge is ∼16% in the lowland coastal area of the Chaliyar river basin and 29% in midland region; (2) northeast winter monsoon rains contribute to the groundwater of Chaliyar river basin only in an insignificant manner, and with a delayed response; (3) unlike river water samples which exhibit both seasonal and spatial variation of more than 3‰, the groundwater samples vary only marginally (∼1‰) between the seasons and across the physiographic zones; (4) groundwater samples exhibit inverse altitude gradient in δ 18 O values in the highland zone, in all the three seasons. This may be due to flow of the isotopically depleted groundwater down the gradient and evaporation of residual water in the upper reaches of the basin.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1 Author(s): Ashish Sharma

Description: Publication date: Available online 16 May 2015 Source: Journal of Hydrology: Regional Studies Author(s): E.H. Elias , A. Rango , C.M. Steele , J.F. Mejia , R. Smith Study region Upper Rio Grande, Colorado and New Mexico, USA. Study focus Climate change is predicted to further limit the water availability of the arid southwestern U.S. We use the snowmelt runoff model to evaluate impacts of climate change on snow covered area (SCA), streamflow timing and runoff volume. Simulations investigate four future conditions using models downscaled to existing climate stations. Twenty-four subbasins of the Upper Rio Grande containing appreciable snowmelt and a long-term gauging station are simulated. New hydrological insights for the region Future annual volume is 193–204 million m 3 more to 448–476 million m 3 less than the pre-climate change value of 2688 million m 3 . There is disparity between increased volume in wetter simulations (+7%) and decreased volume (−18%) in drier simulations. SCA on 1 April reduced by approximately 50% in all but the warmer/wetter climate. Peak flow is 14–24 days early in the future climates. Among the 24 subbasins there is considerable range in mean melt season SCA (−40% to −100%), total volume change (−30% to +57%) and runoff timing advancement indicating that climate change is best evaluated at the subbasin scale. Daily hydrographs show higher streamflow in March and April, but less from mid-May until the end of the water year. The large decrease in volume in May, June and July will compound water management challenges in the region.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1 Author(s): Mohammad Kamruzzaman

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): Jean-Michel Lemieux , Jalil Hassaoui , John Molson , René Therrien , Pierre Therrien , Michel Chouteau , Michel Ouellet Study region This study is conducted in the Magdalen Islands (Québec, Canada), a small archipelago located in the Gulf of St. Lawrence. Study focus This work was undertaken to support the design of a long-term groundwater monitoring network and for the sustainable management of groundwater resources. This study relies mostly on the compilation of existing data, but additional field work has also been carried out, allowing for the first time in the Magdalen Islands, direct observation of the depth and shape of the transition zone between freshwater and seawater under natural conditions. Simulations were conducted along a 2D cross-section on Grande Entrée Island in order to assess the individual and combined impacts of sea-level rise, coastal erosion and decreased groundwater recharge on the position of the saltwater–freshwater interface. The simulations were performed considering variable-density flow and solute transport under saturated-unsaturated conditions. The model was driven by observed and projected climate change scenarios to 2040 for the Magdalen Islands. New hydrological insights for the region The simulation results show that among the three impacts considered, the most important is sea-level rise, followed by decreasing groundwater recharge and coastal erosion. When combined, these impacts cause the saltwater–freshwater interface to migrate inland over a distance of 37 m and to rise by 6.5 m near the coast to 3.1 m further inland, over a 28-year period.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): M.A. Pascolini-Campbell , Richard Seager , David S. Gutzler , Benjamin I. Cook , Daniel Griffin Study region The Gila River, New Mexico, is characterized by two peaks in streamflow: one in the winter–spring (December–May), and summer (August–September). The region is influenced both by Pacific SST variability as well as the North American Monsoon. Study focus The mechanisms responsible for the variability of the winter–spring and summer streamflow peaks are investigated by correlation of streamflow with precipitation and sea surface temperature for 1928–2012. Decadal variability in the flow record is examined for a longer term perspective on Gila River streamflow using tree ring-based reconstructions of the Palmer Drought Severity Index (PDSI) and the Standardized Precipitation Index (SPI). New hydrological insights for the region Results indicate a strong influence of winter–spring precipitation and Pacific SST anomalies on the winter–spring streamflow, with El Niño conditions in the Pacific causing increased precipitation and streamflow. Decadal Pacific variability helps explain the transition from high winter flow in the late 20th century to lower flows in the most recent decade. The summer streamflow has a somewhat weaker correlation with precipitation and Pacific SST than the winter–spring streamflow. Its variability is more likely influenced by local North American Monsoon precipitation variability. PDSI and SPI reconstructions indicate much more severe and extended periods of droughts and pluvials in past centuries as well as periods of concurrent winter and summer drought.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): Tsou Jaw , Jialun Li , Kuo-lin Hsu , Soroosh Sorooshian , Fatima Driouech Study region Morocco (excluding Western Sahara). Study focus This study evaluated Moroccan precipitation, dynamically downscaled (0.18-degree) from three runs of the studied GCM ECHAM5/MPI-OM, under the present-day (1971–2000/20C3M) and future (2036–2065/A1B) climate scenarios. The spatial and quantitative properties of the downscaled precipitation were evaluated by a verified, fine-resolution reference. The effectiveness of the hydrologic responses, driven by the downscaled precipitation, was further evaluated for the study region over the upstream watershed of Oum er Rbia River located in Central Morocco. New hydrological insights for the region The raw downscaling runs reasonably featured the spatial properties but quantitatively misrepresented the mean and extreme intensities of present-day precipitation. Two proposed bias correction approaches, namely stationary Quantile-Mapping (QM) and non-stationary Equidistant CDF Matching model (EDCDFm), successfully reduced the system biases existing in the raw downscaling runs. However, both raw and corrected runs projected great diversity in terms of the quantity of future precipitation. Hydrologic simulations performed by a well-calibrated Variable Infiltration Capacity model successfully reproduced the present-day streamflow. The driven flows were identified highly correlated with the effectiveness of the downscaled precipitation. The future flows were projected to be markedly diverse, mainly due to the varied precipitation projections. Two of the three flow simulation runs projected slight to severe drying scenarios, while another projected an opposite trend for the evaluated future period.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): Megersa Olumana Dinka , Willibald Loiskandl , Julius Musyoka Ndambuki Study region The Matahara region is located in the East Showa zone of Oromiya regional state (Ethiopia). Matahra Sugar Estate and Lake Basaka (highly saline, alkaline and sodic lake) are situated within the flat plains of Matahara region. The area is vulnerable to the occurrences of various tectonic and volcanic activities due to its location in the upper most part of the Main Ethiopian Rift Valley region. Study focus In this study, the hydrochemical properties of different surface water and groundwater bodies available at Matahara region have been characterized for quality compositions. Water samples were collected from different water sources and analyzed for important major quality parameters following standard test procedures. Other chemical indices were derived from the measured quality parameters. The potential sources of minerals were suggested for each of the considered water sources based on their quality characteristics. New hydrological insights for the region Overall, the study result elucidates that the chemical composition of different water bodies are due to natural processes and/or anthropogenic activities within the region. The local anthropogenic processes could be discharges from factory, domestic sewage and farming activities. Some of the water types are found to have relatively higher concentration of dissolved constituents. Irrigation waters have almost equal chemical compositions, indicating their hydrochemical sources are almost the same. Most of the concentrations are relatively high in Lake Basaka, groundwater and hot springs. It is easy to imagine the potential damaging effects of such quality waters on crop production, soil properties and environment of the region.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): Julianne Hagarty , David Azanu , Bernadette Atosona , Ray Voegborlo , Erica A.H. Smithwick , Kamini Singha Study region Buruli ulcer, an emerging disease caused by Mycobacterium ulcerans , largely affects poor rural populations in tropical countries. The environmental niche that supports this necrotizing bacterium is unclear. Here, water samples were collected from five communities within Ghana in the rainy season in 2011: four in the southern part of Ghana (three disease-endemic communities: Pokukrom, Betenase, and Ayanfuri, and one control: Kedadwen) and one non-endemic community (Nangruma) in the north. Study focus Past studies of Buruli ulcer conclude that water quality is, in some way, closely related to the transmission of this disease. This work serves as a first step to explore links between Buruli ulcer incidence and water quality. More broadly, this research works toward identifying the environmental niche for M. ulcerans , providing characterization of water bodies hazardous to human health in at-risk communities. New hydrological insights Trace metals, thought to aid in the preferential growth of M. ulcerans , are present in higher concentrations in mining pits and stagnant pools than in other tested water bodies. Arsenic in particular could serve as a double threat for BU incidence: it could support the growth of M. ulcerans while suppressing immune systems, making the population more susceptible to disease. Few other differences between endemic and non-endemic communities exist, implying other variables such as human behavior may also control the onset of Buruli ulcer.

Description: Publication date: Available online 18 April 2015 Source: Journal of Hydrology: Regional Studies Author(s): Fabrice Papa , Frédéric Frappart , Yoann Malbeteau , Mohammad Shamsudduha , Venugopal Vuruputur , Muddu Sekhar , Guillaume Ramillien , Catherine Prigent , Filipe Aires , Rajesh Kumar Pandey , Sujit Bala , Stephane Calmant Study region The Ganges–Brahmaputra (GB), a major river basin of the Indian Sub-Continent (ISC), is the host of more than 700 millions people. Study focus In addition to monsoons and strong climate variability, GB is facing growing demands for freshwater availability by a continually growing population and rapidly developing of agricultural and industrial sectors. The management of water resources is thus of highest priority and, in the context of current over-abstraction of groundwater, accurate estimates of terrestrial freshwater storage are essential. We propose a multi-satellite approach to estimate surface freshwater storage (SWS) and subsurface water storage (SSWS, groundwater + soil moisture) variations over GB. New hydrological insights Basin-scale monthly SWS variations for the period 2003–2007 show a mean annual amplitude of ∼410 km 3 , contributing to about 45% of the Gravity Recovery And Climate Experiment (GRACE)-derived total water storage variations (TWS). During the drought-like conditions in 2006, we estimate that the SWS deficit over the entire GB basin in July–August–September was about 30% as compared to other years. The SWS variations are then used to decompose the GB GRACE-derived TWS and isolate the variations of SSWS whose mean annual amplitude is estimated to be ∼550 km 3 . This new dataset of water storage variations represent an unprecedented source of information for hydrological and climate modeling studies of the ISC.

Description: Publication date: Available online 7 April 2015 Source: Journal of Hydrology: Regional Studies Author(s): Swati Verma , Abhijit Mukherjee , Runti Choudhury , Chandan Mahanta Study region Brahmaputra River basin, India. Study focus The present study deciphers the groundwater solute chemistry and arsenic (As) enrichment in the shallow aquifers of the study region. Four different geomorphologic units, e.g. piedmont (PD), older alluvium of river Brahmaputra and its tributaries (OA), active alluvium of river Brahmaputra and its tributaries (YA) and river channel deposits (RCD) were identified. More than 62% of all groundwater samples collected have dissolved As >0.01 mg/L, whereas about 87% of groundwater samples in OA terrain are enriched with As, which draws a distinct difference from the adjoining Gangetic aquifers. New hydrological insights for the region Most groundwater solutes of RCD and YA terrains were derived from both silicate weathering and carbonate dissolution, while silicate weathering process dominates the solute contribution in OA groundwater. Groundwater samples from all terrains are postoxic with mean pe values between Fe(III) and As(V)–As(III) reductive transition. While, reductive dissolution of (Fe–Mn)OOH is the dominant mechanism of As mobilization in RCD and YA aquifers, As in OA and PD aquifers could be mobilized by combined effect of pH dependent sorption and competitive ion exchange. The present study focuses on the major ion chemistry as well as the chemistry of the redox sensitive solutes of the groundwater in different geomorphic settings and their links to arsenic mobilization in groundwater.

Description: Publication date: Available online 11 March 2015 Source: Journal of Hydrology: Regional Studies Author(s): B.M. Hallett , H.A. Dharmagunawardhane , S. Atal , E. Valsami-Jones , S. Ahmed , W.G. Burgess Study region The Maheshwaram and Waipally catchments of Andhra Pradesh, India, and the Plonnaruwa catchment of north-central Sri Lanka. Study focus The distribution of F across eight crystalline phases and between the bedrock and the regolith at eleven sites in three catchments is documented. Mineral contributions to F release during weathering and regolith development are quantified. New hydrological insights for the region An estimate of weathering duration for the in situ regolith in Andhra Pradesh, 250–380 Ka, is close to a previous estimate for southern India. Partial or total destruction of the primary F-bearing bedrock minerals and consistent depletion of F in the remnant minerals result in a much reduced total F content in the regolith. Leaching experiments and field relationships, however, indicate a greater potential for F mobilisation to groundwater from the regolith than the bedrock. Schemes for managed aquifer recharge should beware the risk of mobilising additional F to groundwater.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1 Author(s): Salah Er-Raki

Description: Publication date: Available online 10 December 2015 Source: Journal of Hydrology: Regional Studies Author(s): Tatsuya Utsunomiya, Masaki Hata, Ryo Sugimoto, Hisami Honda, Shiho Kobayashi, Yoji Miyata, Makoto Yamada, Osamu Tominaga, Jun Shoji, Makoto Taniguchi Study focus There have been far more studies on how the variability in surface water discharge affects production of animal communities in aquatic ecosystems while less information has been accumulated on the mechanisms of how the groundwater supply works. Study region Physical and biological surveys were conducted to test the hypothesis that high level of submarine ground water discharge enhances species richness, abundance and biomass of fishes and invertebrates in coastal waters of Obama Bay, Japan, where a high contribution of nutrients (ca. 65% of phosphorus) to total provided through all freshwater has been reported. Survey for horizontal distribution of radon-222 ( 222 Rn) concentration showed high levels of submarine groundwater discharge in the west part of survey area. Fish and invertebrate communities were compared within a relatively small spatial scale (ca. 100 m) in relation to level of submarine groundwater discharge. New hydrological insights Species richness, abundance and biomass of fishes and abundance and biomass of turban snail and hermit crab were significantly higher in the area with high 222 Rn concentration. Abundance of gammarids, the most major prey item of the fishes, was 18 times higher in the area with high 222 Rn concentration. Since the turban snail, hermit crab and gammarids feed on producers (phytoplankton and benthic microalgae), submarine groundwater are concluded to increase species richness and production of fishes and invertebrates through providing nutrients and enhancing primary production.

Description: Publication date: March 2016 Source: Journal of Hydrology: Regional Studies, Volume 5 Author(s): A.C. de la Casa, G.G. Ovando Study region Changes in reference evapotranspiration (ET o ) may have important consequences for agricultural suitability in the central region of Argentina. Annual ET o variation was assessed, in terms of both territory and time, for the 7 decades between 1941 and 2010, analyzing the behavior of the 4 atmospheric variables which determine it: temperature, vapor pressure, wind speed and cloud cover. Study focus The influence of each variable on ET o was evaluated from a multiple regression model and a simple correlation analysis, using climate data from the observation network, and repeating this analysis using interpolated variables. In this grid scheme, linear relationships were determined between ET o and the different key atmospheric variables, plus precipitation (PP), and the t test was applied to establish the statistically significant sectors ( P 〈 0.1). Then, those areas with a significant trend change ( P 〈 0.1) were determined by the Mann–Kendall test. Finally, the interception of the grids was performed to establish their joint occurrence. New hydrological insights for the region Most of the region analyzed (>91%) presents a non-significant variation of ET o over time, with a mostly non-significant change of each driving variable, regarding both its relationship with ET o and its own trend of change. The beneficial change in agricultural suitability reported for this water-limited region was found to be produced almost exclusively by increasing PP. Graphical abstract

Description: Publication date: Available online 11 December 2015 Source: Journal of Hydrology: Regional Studies Author(s): Makoto Taniguchi, Naoki Masuhara, Kimberly Burnett Security measures of three resources; water, energy and food are analyzed for thirty two countries in the Asia Pacific region which are faced to Pacific Ocean, in terms of amounts of the resource, self-production, and diversity of sources of each resource. Diversity for all the three resources is also analyzed using surface water and groundwater for water sources; hydro power, geothermal power, solar, and biomass for energy; and cereals, vegetable, fruit, meat, and fish for food. We see high diversity of sources of water in the US and the Philippines, and a low diversity of sources of food in the US, Canada, and Indonesia. These security measures including water security show new hydrological insight for Asia-Pacific region.

Description: Publication date: Available online 10 December 2015 Source: Journal of Hydrology: Regional Studies Author(s): Aiko Endo, Izumi Tsurita, Kimberly Burnett, Pedcris M. Orencio Study region Asia, Europe, Oceania, North America, South America, Middle East and Africa. Study focus The purpose of this paper is to review and analyze the water, energy, and food nexus and regions of study, nexus keywords and stakeholders in order to understand the current state of nexus research. New hydrological insights Through selected 37 projects, four types of nexus research were identified including water–food, water–energy–food, water–energy, and climate related. Among them, six projects (16%) had a close linkage with water–food, 11 (30%) with water–energy–food, 12 (32%) with water–energy, and eight (22%) with climate. The regions were divided into Asia, Europe, Oceania, North America, South America, Middle East and Africa. North America and Oceania had a tendency to focus on a specific nexus type, water–energy (46%) and climate (43%), while Africa had less focus on water–energy (7%). Regarding keywords, out of 37 nexus projects, 16 projects listed keywords in their articles. There were 84 keywords in total, which were categorized by the author team depending on its relevance to water, food, energy, climate, and combination of water–food–energy–climate, and 40 out of 84 keywords were linked with water and only 4 were linked with climate. As for stakeholders, 77 out of 137 organizations were related to research and only two organizations had a role in media.

Description: Publication date: March 2016 Source: Journal of Hydrology: Regional Studies, Volume 5 Author(s): Shilpa M. Asokan, Peter Rogberg, Arvid Bring, Jerker Jarsjö, Georgia Destouni Study region The large semi-arid Aral Region in Central Asia and the smaller tropical Mahanadi River Basin (MRB) in India. Study focus Few studies have so far evaluated the performance of the latest generation of global climate models on hydrological basin scales. We here investigate the performance and projections of the global climate models in the Coupled Model Intercomparison Project, Phase 5 (CMIP5) for freshwater fluxes and their changes in two regional hydrological basins, which are both irrigated but of different scale and with different climate. New hydrological insights for the region For precipitation in both regions, model accuracy relative to observations has remained the same or decreased in successive climate model generations until and including CMIP5. No single climate model out-performs other models across all key freshwater variables in any of the investigated basins. Scale effects are not evident from global model application directly to freshwater assessment for the two basins of widely different size. Overall, model results are less accurate and more uncertain for freshwater fluxes than for temperature, and particularly so for model-implied water storage changes. Also, the monsoon-driven runoff seasonality in MRB is not accurately reproduced. Model projections agree on evapotranspiration increase in both regions until the climatic period 2070–2099. This increase is fed by precipitation increase in MRB and by runoff water (thereby decreasing runoff) in the Aral Region.

Description: Publication date: March 2016 Source: Journal of Hydrology: Regional Studies, Volume 5 Author(s): Justin A. Schulte, Raymond G. Najjar, Ming Li Study region The Mid-Atlantic region of the United States. Study focus An understanding of past streamflow variability is necessary for developing future management practices that will help mitigate the impacts of extreme events such as drought or floods on agriculture and other human activities. To better understand mechanisms driving streamflow variability at all timescales, annual to multi-decadal streamflow variability of three major rivers in the Mid-Atlantic region of the United States (the Susquehanna, Delaware, and Hudson Rivers) was studied in the context of climate modes using correlation and wavelet analyses. New hydrological insights for the region Results from the correlation analysis detected statistically significant relationships between climate indices and streamflow that were similar for the three rivers. The results from the wavelet analysis showed that 18- and 26-year periodicities were embedded in the streamflow time series. Decadal variability of streamflow was coherent with the El-Niño Southern Oscillation (SO) and the Pacific Decadal Oscillation (PDO). The time series for the PDO and SO indices and precipitation were found to be synchronized to the decadal variability of a global circulation pattern consisting of a Rossby wave train emanating from the North Pacific. The SO explained 37–54% of the 1960s drought, 33–49% of the 1970s pluvial, and 19–50% of the 2000s pluvial in the three river basins.

Description: 〈p〉Publication date: October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 19〈/p〉 〈p〉Author(s): José Bandeira Brasil, Eunice Maia de Andrade, Helba Araújo de Queiroz Palácio, Pedro Henrique Augusto Medeiros, Julio Cesar Neves dos Santos〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study region〈/h6〉 〈p〉Iguatu Experimental Basin, located in the semi-arid region of northeastern Brazil.〈/p〉 〈/div〉 〈div〉 〈h6〉Study focus〈/h6〉 〈p〉The aim of this study was to investigate the influence of rainfall characteristics on throughfall, stemflow and interception loss in a deciduous forest of a tropical semi-arid region, from a data series of eight consecutive years. The data were collected from 2010 to 2017, comprising a total of 225 events.〈/p〉 〈/div〉 〈div〉 〈h6〉New hydrological insights for the region〈/h6〉 〈p〉Among the variables used to characterize rainfall, the maximum 30-min intensity (〈em〉I30〈/em〉) best explained the interception losses, which is also well correlated to rainfall depth and event average intensity. The predominant events (67% of the total) are characterised by low rainfall depth, low 〈em〉I30〈/em〉 and higher interception loss (18% of the gross rainfall). In addition, there is a threshold between rainfall characteristics and the interception process: for rainfall and 〈em〉I30〈/em〉 lower than 20 mm and 15 mm/h respectively, and rainfall duration lower than 100 min, interception losses are usually higher than 30%, reaching up to 74%. For the remaining events, interception losses are mostly within the range of 10–20% of rainfall. The data and information on the interception process, presented in this study, helps the comprehension of the overall water balance in dry environments and improve the capacity for parameterization of hydrological models, contributing to a more efficient water and environmental management.〈/p〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 21〈/p〉 〈p〉Author(s): L. Myeni, M.E. Moeletsi, A.D. Clulow〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Soil moisture is the key parameter that governs the partitioning of the mass and energy fluxes between land and atmosphere through its influence on surface evaporation, runoff, albedo and emissivity. Therefore, accurate quantification of soil moisture is critical in the study of the soil-plant-atmosphere continuum as well as in hydrology and climate change studies. However, soil moisture remains a challenging hydrometeorological variable to monitor and interpret over high temporal and spatial resolution. The cost of setting up, operating and maintaining dense soil moisture networks across different agro-climatic zones of the African regions is currently financially unattainable due to high competition for resources. Consequently, soil moisture is often estimated indirectly, using both remote sensing and hydrological models, which provide periodic updates and valuable estimates at lower cost over African continent thus far. In recent years, huge efforts have been undertaken to install in situ soil moisture monitoring networks to support the satellite retrievals, satellite product improvement and modelling in Africa. However, the lack of large and representative in situ soil moisture monitoring networks across different agro-climatic zones of the African regions still hinders evaluation and verification of the most promising remote sensing products and hydrological models to estimate soil moisture. Consequently, the need for accurate and continuous real-time in situ soil moisture measurements covering a wide range of agro-climatic zones of the African continent is indisputable.〈/p〉〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 21〈/p〉 〈p〉Author(s): Johanna Ngula Niipele, Jianping Chen〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study region〈/h6〉 〈p〉The study area is the Iishana sub-basin located in north-central Namibia. The basin is characterised by low-lying interconnected ephemeral drainage networks locally known as Iishana. In the past decade, the basin has experienced frequent droughts and flooding events due to recent weather anomalies possibly enhanced by the sprawling urban development.〈/p〉 〈/div〉 〈div〉 〈h6〉Study focus〈/h6〉 〈p〉Although extensive studies have been conducted on water availability in the basin, no attempts have been made to update existing hydrological maps which provide limited information on the impacts of geo-hydrological dynamics in the area. The aim of this study was to test the effectiveness of the Advanced Land Observing Satellite Digital Elevation Model (ALOS DEM) for drainage network extraction. ArcHydro tools were used for drainage feature extraction. Validation of extracted networks was based on field observations and delineated networks from earth observation data and Normalized Difference Wetness Index (NDWI). The accuracy of extracted drainage networks was assessed through visual observation of data overlay and the coefficient of line correspondence (CLC).〈/p〉 〈/div〉 〈div〉 〈h6〉New hydrological insights〈/h6〉 〈p〉The resulting drainage networks will be used to update the current hydrographic map of the area which will aid in the development of flood and drought mitigating measures for environmental management. The CLC computed metric obtained a 0.91 match between extracted and delineated drainage networks. The results show that ALOS DEM is capable of extracting drainage networks within the Iishana sub-basin.〈/p〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 21〈/p〉 〈p〉Author(s): Ameer Muhammad, Grey R. Evenson, Tricia A. Stadnyk, Alaba Boluwade, Sanjeev Kumar Jha, Paulin Coulibaly〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study region〈/h6〉 〈p〉Prairie Pothole Region of Canada.〈/p〉 〈/div〉 〈div〉 〈h6〉Study focus〈/h6〉 〈p〉The Prairie region spans across approximately 870,000 km〈sup〉2〈/sup〉 of the Great Plains region of Canada (80%) and the United States (20%). The presence of a large number of depressional wetlands (potholes) results in dynamic surface-water and stream connectivity during wet and dry year necessitating an improved understanding of watershed-scale interactions of the Prairie Potholes. The Soil Water Assessment Tool (SWAT) hydrological model with three structural variants is utilized to assess the degree of accuracy associated with increasing model complexity and its impact on the model calibration of the Upper Assiniboine River Basin at Kamsack.〈/p〉 〈/div〉 〈div〉 〈h6〉New hydrologic insight for the region〈/h6〉 〈p〉The SWAT model was calibrated and verified with three different structural arrangements in 1) lumped pothole, 2) semi discretized pothole, 3) and fully discretized pothole representation. The fully discretized pothole version of the SWAT reflected streamflow best (KGE of 0.78) but with greater uncertainty, larger data and computational resource requirements. The fully discretized (modified) model, however, was able to capture the high flow and the fill-and-spill processes, which is a defining characteristic of the Prairie Pothole Region (PPR). Significant improvements to the predictive ability of SWAT in the case of the modified model was observed, thus allowing an enhanced understanding of the aggregate effect of potholes in this watershed.〈/p〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 21〈/p〉 〈p〉Author(s): Ann W. Kamamia, Hosea M. Mwangi, Karl-Heinz Feger, Stefan Julich〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study region〈/h6〉 〈p〉Nyangores catchment, Mara catchment, Kenya.〈/p〉 〈/div〉 〈div〉 〈h6〉Study focus〈/h6〉 〈p〉Hydrologic models are widely used tools in watershed management to assist in decision making by representing catchment functions under alternative scenarios. This study focused on the evaluation of the 5 segment Flow Duration Curve based calibration procedure (5FDC) for the period 1975–1978 using the Soil Water Assessment Tool (SWAT). The Normal Calibration Procedure (NCP) based on the hydrograph was compared to the 5FDC. Two separate ensembles each containing 10 Pareto calibration runs were obtained individually from each method and evaluated based on their goodness-of-fit. A final Combined Procedure (CP), which was an intersection of 5FDC and NCP was executed. With this supplementary analysis, the parameter distribution and water component balance were analyzed and compared.〈/p〉 〈/div〉 〈div〉 〈h6〉New hydrological insights for the region〈/h6〉 〈p〉The comparison of 5FDC and NCP shows that the 5FDC provides a better representation of the low and mid-level section of the flow duration curve as compared to the NCP, which greatly overestimates these flows. This method also closely matches the observed runoff ratios. This indicates that the 5FDC calibration may be well suited for water resource applications focused on low flows. The CP combines the advantages of both procedures by improving parameter identifiability, leading to better representation of high and low flows.〈/p〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 21〈/p〉 〈p〉Author(s): Makoto Higashino, Heinz G. Stefan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study region〈/h6〉 〈p〉The Banjo River basin on Kyushu Island in the southwest of Japan.〈/p〉 〈/div〉 〈div〉 〈h6〉Study focus〈/h6〉 〈p〉This study focuses on the impact of local and/or large scale climate change on the river flow in the small and steep river basin. The variability, trend, correlation and change of extreme and mean precipitation and river (flood) runoff are investigated.〈/p〉 〈/div〉 〈div〉 〈h6〉New hydrological insights〈/h6〉 〈p〉In the small and steep river basins of Japan, the maximum annual flood runoff which occurs in the wet season, is well correlated with maximum precipitation on a daily time scale. Daily flow and precipitation data recorded in the basin from 1960 to 2015, have a correlation coefficient R〈sup〉2〈/sup〉 = 0.72. A high variability of the maximum and mean annual flows, and significant rising trends in daily extreme precipitation and river (flood) flows were also found in the data analysis. The maximum annual flood has increased on average by 5.98 m〈sup〉3〈/sup〉/s per year from 330 m〈sup〉3〈/sup〉/s in 1960; this increase is fully accounted for by the trend in observed maximum annual precipitation which is 1.1 mm/day per year. On an annual timescale maximum precipitation and maximum flood discharges have become substantially higher in phase with the ENSO (El Nino-Southern Oscillation) in the Pacific Ocean. Time frequency analyses revealed that a periodic component of the annual maximum flood flow in the Banjo River basin with a period of about 6 to 8 years has become significant since the beginning of the 21 st century. The number of days with more than 100, 200, 300, 400 and 500 m〈sup〉3〈/sup〉/s flows has increased, which is important for flood control planning.〈/p〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 21〈/p〉 〈p〉Author(s): J.J. Gibson, S.J. Birks, M. Moncur〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study region〈/h6〉 〈p〉Surveys of stable isotopes of water in 121 lakes were conducted between 2007 and 2009 to assist in characterizing baseline hydrology of the South Athabasca Oil Sands area, Alberta, a 35,000 km〈sup〉2〈/sup〉 boreal forest region with subdued relief, about 70% wetland cover, and a mosaic of lakes, rivers and buried channel networks. The region, currently under rapid development for in-situ oil sands, was close to baseline conditions at the time of survey.〈/p〉 〈/div〉 〈div〉 〈h6〉Study focus〈/h6〉 〈p〉Using an isotope mass balance approach, isotope data were applied to estimate water yield to lakes across the region. High-resolution maps were created to illustrate the spatial distribution of water yield and to compare observed patterns to geologic and physiographic features.〈/p〉 〈/div〉 〈div〉 〈h6〉New hydrological insights for the region〈/h6〉 〈p〉Site-specific differences in water yield were found in relation to geologic and physiographic features. Notably, high water yields were found in lakes underlain by Colorado shale, lower runoff was found in proximity to incised and buried channels. Consistent patterns from year-to-year reveal zones of low runoff which may be more susceptible to development-related impacts including changes in surface/groundwater interaction and pressurization or depressurization of aquifers or formations. The approach may be helpful for informing design of new monitoring programs to ensure runoff variability is considered. Periodic reassessments are recommended to capture potential development and/or climatic change impacts on the water cycle.〈/p〉 〈/div〉

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Abdouramane Gado Djibo , Ousmane Seidou , Harouna Karambiri , Ketevera Sittichok , Jean Emmanuel Paturel , Hadiza Moussa Saley Study region The Sirba watershed, Niger and Burkina Faso countries, West Africa. Study focus Water resources management in the Sahel region, West Africa, is extremely difficult because of high inter-annual rainfall variability. Unexpected floods and droughts often lead to severe humanitarian crises. Seasonal rainfall forecasting is one possible way to increase resilience to climate variability by providing information in advance about the amount of rainfall expected in each upcoming rainy season. Rainfall forecasting models often arbitrarily assume that rainfall is linked to predictors by a multiple linear regression with parameters that are independent of time and of predictor magnitude. Two probabilistic methods based on change point detection that allow the relationship to change according to time or rainfall magnitude were developed in this paper using normalized Bayes factors. Each method uses one of the following predictors: sea level pressure, air temperature and relative humidity. Method M1 allows for change in model parameters according to annual rainfall magnitude, while M2 allows for changes in model parameters with time. M1 and M2 were compared to the classical linear model with constant parameters (M3) and to the climatology (M4). New hydrological insights for the region The model that allows a change in the predictor–predictand relationship according to rainfall amplitude (M1) and uses air temperature as predictor is the best model for seasonal rainfall forecasting in the study area.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Frank Joseph Wambura, Preksedis Marco Ndomba, Victor Kongo, Siza Donald Tumbo Study Region The Wami River sub-basin is among the river sub-basins with a vital ecosystem in Tanzania. It comprises the Saadani National park and it has the very great potential of irrigation and rain fed agriculture. Study Focus The objective of this study was to evaluate the uncertainty of future streamflow in respect of increasing water demands and uncertain projected climate inputs, General Circulation Models (GCMs). The water demands were projected to the year 2039 and GCM precipitation was selected as the changing climatic variable. The CMIP5-GCMs were evaluated for their skills and those with the minimum skill scores above 75% were downscaled and used in projection of scenario RCP 8.5 precipitation. Then uncertainties of RCP 8.5 precipitation were estimated using a fuzzy extension principle and finally used to simulate uncertainties of future runoff using a rainfall-runoff model, Soil and Water Assessment Tool (SWAT). New Hydrological Insights for the Region The results of projected streamflow shows that the baseline annual climatology flow (ACF) is 98 m 3 /s and for the future, the median ACF is projected to be 81 m 3 /s. At 100% uncertainty of skilled projections, the ACF from the sub-basin is projected to range between −47% and +36% from the baseline ACF. However, the midstream of the sub-basin shows reliable water availability for foreseen water uses expansion up to the year 2039.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Fernando Mainardi Fan , Dirk Schwanenberg , Walter Collischonn , Albrecht Weerts Study region This paper describes a major ensemble-forecasts verification effort for inflows of three large-scale river basins of Brazil: Upper São Francisco, Doce, and Tocantins Rivers. Study focus In experimental scenarios, inflow forecasts were generated forcing one hydrological model with quantitative precipitation forecasts (QPF) from three selected models of the TIGGE database. This study provides information on the regional ensemble performance and also evaluates how different QPF models respond for the different basins and what happens with the use of combined QPF in a greater ensemble. New hydrological insights for the region This work presents one of the first extensive efforts to evaluate ensemble forecasts for large-scale basins in South America using TIGGE archive data. Results from these scenarios provide validation criteria and confirm that ensemble forecasts depend on the particular EPS used to run the hydrological model and on the basin studied. Furthermore, the use of the Super Ensemble seems to be a good strategy in terms of performance and robustness. The importance of the TIGGE database is also highlighted.

Description: Publication date: Available online 17 December 2015 Source: Journal of Hydrology: Regional Studies Author(s): Jun Nishijima, Kento Naritomi Study region The area of the Beppu geothermal field is located in southeast Japan (33°15′ to 20′ N, 131°27′ to 32′ E). Study focus The Beppu geothermal field, which is one of the largest hot-spring resorts, is located in the eastern end of the Beppu-Shimabara Graben, in central Kyushu, Japan. Details of the subsurface structure are necessary for hydrothermal modeling and numerical simulation. This study aims to delineate the shallow underground fault and basement structure using gravity analysis. New hydrological insights for the region A high Bouguer anomaly is detected in the southern part of this area, which corresponds to the distribution of the Kankaiji andesite. The results of the edge-detection filter of gravity data indicate that the northern edge of the high Bouguer anomaly corresponds to the Asamigawa Fault in the southern part of the study area, but deviates 1 km southeast of the Kankaiji hot spring to the north. In this area of high value, which indicates the fault, three hot spring areas, Horita, Kankaiji and Hamawaki, are located. The distribution of the depths of the three-dimensional gravity basement enables the delineation of the interface between the volcanic basement rocks and the fan deposit. The conspicuous, steep slope of the gravity basement is detected along the Asamigawa Fault and the southern hot-spring area. However, the northern hot-spring area is distributed on the uplift of the gravity basement. The results of the gravity analysis indicate that the structure of the hot-spring water path differs between the southern and northern hot-spring areas.

Description: Publication date: March 2016 Source: Journal of Hydrology: Regional Studies, Volume 5 Author(s): Ningfang Yang, Zhixiong Shen, Saugata Datta, Karen H. Johannesson Study region The Mississippi Delta in southern Louisiana, United States. Study focus The probable role that microbial respiration plays in As release from the shallow aquifer sediments. New hydrological insights for the region Shallow groundwaters in southern Louisiana have been reported to contain elevated As concentrations, whereas mechanisms responsible for As release from sediments have rarely been studied in this region. Microbial respiration is generally considered the main mechanism controlling As release in reducing anoxic aquifers such as the shallow aquifers in southern Louisiana and those of the Bengal basin. This study investigates the role microbial respiration plays in As release from shallow aquifer sediments in southern Louisiana through sediment incubation experiments and porewater analysis. Arsenic concentrations were the lowest in the sterilized control experiments, slightly higher in the un-amended experiments, and the highest in the experiments amended with acetate, and especially those amended with both acetate and AQDS (9,10-anthraquinone-2,6-disulfonic acid). Although Fe and Mn generally decreased at the beginning of all the experiments, they did follow a similar trend to As after the decrease. Porewater analysis showed that As and Fe concentrations were generally positively correlated and were higher in the coarse-grained sediments than in the fine-grained sediments. Results of the investigation are consistent with microbial respiration playing a key role in As release from the shallow aquifers sediments in southern Louisiana.

Description: Publication date: Available online 24 March 2015 Source: Journal of Hydrology: Regional Studies Author(s): Jonathan Spinoni , Gustavo Naumann , Jürgen V. Vogt , Paulo Barbosa Study region Europe, including European Russia, but excluding Greenland, the Canary Islands, the Azores, and Madeira. Study focus Drought is a complex climate-related phenomenon that can affect different sectors causing economic, social, and environmental impacts. We focus on meteorological and hydrological droughts, defined as shortage of precipitation over several months and we discuss the biggest drought events in 1950–2012. To define such drought events we computed three drought indicators, the Standardized Precipitation Index, the Standardized Precipitation Evapotranspiration Index, and the Reconnaissance Drought Index and we merged them into a combined indicator at 3-month scale for meteorological and 12-month for hydrological droughts. The indicators have been calculated using the E-OBS gridded data (0.25° × 0.25°). New hydrological insights for the region Europe has been subdivided into thirteen regions and for each region we determined a list of drought events. The events have been characterized by the time, duration, severity, average area involved, peak month, and area involved at the peak month. We computed time series of the combined indicators for each region and country to determine the twenty-two biggest drought events in 1950–2012. Northern Europe and Russia show the highest drought frequency, duration, and severity in the 1950s and 1960s, where this is for the 1970s in Central Europe and the British Islands, and the 1990s and 2000s for the Mediterranean area and Baltic Republics.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1 Author(s): Hossein Tabari

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1 Author(s): Huade Guan

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1 Author(s): Luca Brocca

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): Ferdinand Beck , András Bárdossy , Jochen Seidel , Thomas Müller , Elvira Fernandez Sanchis , Andreas Hauser Study region The study was conducted with data from the city state of Singapore, a densely populated and highly urbanized island state close to the equator. Study focus The study provides a basic statistical characterization of Singapore's precipitation regime. It quantifies the effects of daily and yearly cycles and the connections to the El Niño Southern Oscillation and Sea Surface Temperature on hourly rainfall amounts. A regional regression analysis was applied to detect trends in hourly and daily precipitation extremes. New hydrological insights for the region • Rainfall events in the early morning and in the afternoon exhibit different spatio-temporal characteristics. • Singapore's precipitation activity is influenced by the El Niño Southern Oscillation, but not during the North-East Monsoon season. During the La Niña phase, seasonal precipitation totals are higher and the arrival of the most intense precipitation events is shifted towards morning hours. • The rainfall regime has been changing during the investigation period from 1981 to 2010. Rainfall totals as well as hourly and daily extremes increased. The increase in daily extremes was the fastest, changing the temporal scaling of the extremes. • The predicted changes in precipitation scaling towards higher daily sums have implications for the management of stormwater run-off.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): Theresa M. Modrick , Konstantine P. Georgakakos Study region Small watersheds (O[25 km 2 ]) in the mountain regions of southern California comprise the study region. Study focus This paper examines changes in flash flood occurrence in southern California resulting from projected climatic change. The methodology synthesizes elements of meteorological modeling, hydrology and geomorphology into an integrated modeling approach to define flash flood occurrence in a systematic and consistent way on a regional basis with high spatial and temporal resolution appropriate for flash flooding. A single climate model with three-dimensional atmospheric detail was used as input to drive simulations for historical and future periods. New hydrological insights for the region Results indicate an increase in flash flood occurrence for the study region. For two distributed hydrologic models employed, the increase in flash flood occurrence frequency is on average between 30% and 40%. Regional flash flood occurrence is characterized by near saturation of the upper soil layer, and wider ranges in lower soil layer saturation and in precipitation. Overall, a decrease in the total number of precipitation events was found, although with increased precipitation intensity, increased event duration, and higher soil saturation conditions for the 21st century. This combination could signify more hazardous conditions, with fewer precipitation events but higher rainfall intensity and over soils with higher initial soil moisture saturation, leading to more frequent occurrence of flash floods.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): M. Kopytkovskiy , M. Geza , J.E. McCray Study region The Upper Colorado River Basin (UCRB), comprised of the Colorado and Gunnison River basins, is the prime water source for much of the western United States. Study focus Future climate change models were used to drive a hydrologic model of the UCRB to evaluate future water resources and hydropower potential of the basin, using three different climate projections. The Intergovernmental Panel on Climate Change (IPCC) emission scenarios, the A2-business as usual, and the B1-reduced emissions scenarios were evaluated. More than 4500 water diversions and 17 reservoirs were incorporated into the hydrologic model. New hydrological insights for the region Precipitation projections from climate models vary up to 16%; flow projections revealed greater differences, up to 50%. The climate models projected increase in temperature at low elevations with extreme seasonality at high elevations, although summer temperatures increased at all elevations. The models projected a 60% decline in precipitation at lower elevations and a 74% increase at high elevations, although precipitation declined during the summer months at all elevations. Using the A2 scenario an overall decrease in annual flow was predicted, attributed to a reduction in precipitation and increasing temperature trends; however, this was not consistent during the winter months, which showed an increase in precipitation at high elevations and a modest temperature increase during the winter and resulted in an increase in stream flow. The responses to climate change on reservoir levels varied basin-wide due to variability in precipitation, evapotranspiration, and stream flow. Simulations indicated that water levels in Blue Mesa Reservoir (the largest reservoir in the UCRB) would decline by more than 70% with increasing annual temperatures. Reservoirs with smaller surface areas to the volume ratio were not significantly impacted by evapotranspiration. Our results indicate that hydropower management strategies in the UCRB must adapt to potential climate change, but the required adaptations are dependent on several factors including reservoir size and location.

Description: Publication date: Available online 2 April 2015 Source: Journal of Hydrology: Regional Studies Author(s): Shashank Shekhar , Roger S.K. Mao , Esther B. Imchen Study region North district of Delhi, India. Study focus The North district of Delhi has mostly shallow water levels and is a groundwater surplus region in contrast to the over-exploited aquifers of the region. The surface runoff and flood waters during monsoon season in the district either causes water logging in lower elevation areas or they join drains and rivers as rejected recharge. This study aims to understand groundwater dynamics of the region in perspective of the aquifer architecture and proposes groundwater management options to meet local water requirements. New hydrological insights in the region Three distinct hydrogeological domains are identified with subtle differences in groundwater occurrence. Insights are obtained in stream–aquifer interaction and baseflow to the Yamuna River is quantified. The salinity enrichment in groundwater has been attributed to water logging in clay rich formations under semi arid condition. The viability of limited dewatering of shallow aquifers and its replenishment by enhanced recharge from surface runoff and flood waters during the monsoon period have been established.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): G. Seiller , I. Hajji , F. Anctil Study region Twenty diversified U.S. watersheds. Study focus Identifying optimal parameter sets for hydrological modeling on a specific catchment remains an important challenge for numerous applied and research projects. This is particularly the case when working under contrasted climate conditions that question the temporal transposability of the parameters. Methodologies exist, mainly based on Differential Split Sample Tests, to examine this concern. This work assesses the improved temporal transposability of a multimodel implementation, based on twenty dissimilar lumped conceptual structures and on twenty U.S. watersheds, over the performance of the individual models. New hydrological insights for the region Individual and collective temporal transposabilities are analyzed and compared on the twenty studied watersheds. Results show that individual models performances on contrasted climate conditions are very dissimilar depending on test period and watershed, without the possibility to identify a best solution in all circumstances. They also confirm that performance and robustness are clearly enhanced using an ensemble of rainfall-runoff models instead of individual ones. The use of (calibrated) weight averaged multimodels further improves temporal transposability over simple averaged ensemble, in most instances, confirming added-value of this approach but also the need to evaluate how individual models compensate each other errors.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3 Author(s): Ibrahim Nourein Mohammed , Arne Bomblies , Beverley C. Wemple Study region Lake Champlain Basin, northwestern New England, USA. Study focus Our study uses regional hydrologic analyses and modeling to examine alternative possibilities that might emerge in the Lake Champlain Basin streamflow regime for various climate scenarios. Climate data as well as spatial data were processed to calibrate the Regional Hydro-Ecological Simulation System (RHESSys) model runoff simulations. The 21st century runoff simulations were obtained by driving the RHESSys model with climate data from the Coupled Model Intercomparison Project phase 5 (CMIP5) for representative concentration pathways RCP 4.5 and 8.5. New hydrological insights for the region Our analyses suggest that most of CMIP5 ensembles fail to capture both the trends and variability observed in historical precipitation when run in hindcast. This raises concerns of using such products in driving hydrologic models for the purpose of obtaining reliable runoff projections that can aid researchers in regional planning. A subset of five climate models among the CMIP5 ensembles have shown statistically significant trends in precipitation, but the magnitude of these trends is not adequately representative of those seen in observed annual precipitation. Adjusted precipitation forecasts project a streamflow regime described by an increase of about 30% in seven-day maximum flow, a four days increase in flooded days, a three orders of magnitude increase in base flow index, and a 60% increase in runoff predictability (Colwell index).

Description: Publication date: Available online 17 April 2015 Source: Journal of Hydrology: Regional Studies Author(s): Abhijit Mukherjee , Dipankar Saha , Charles F. Harvey , Richard G. Taylor , Kazi Matin Ahmed , Soumendra N. Bhanja The Indian Sub-Continent is one of the most densely populated regions of the world, hosting ∼23% of the global population within only ∼3% of the world's land area. It encompasses some of the world's largest fluvial systems in the world (River Brahmaputra, Ganges and Indus Basins), which hosts some of the highest yielding aquifers in the world. The distribution of usable groundwater in the region varies considerably and the continued availability of safe water from many of these aquifers (e.g. Bengal Basin) is constrained by the presence of natural contaminants. Further, the trans-boundary nature of the aquifers in the Indian Sub-Continent makes groundwater resource a potentially politically sensitive issue, particularly since this region is the largest user of groundwater resources in the world. Indeed, there is considerable concern regarding dwindling well yield and declining groundwater levels, even for the highly productive aquifers. Though irrigation already accounts for >85% of the total ground water extraction of the region, there is a mounting pressure on aquifers for food security of the region. Highly variable precipitation, hydrogeological conditions and predicted, impending climate change effects provide substantial challenges to groundwater management. The observed presence of natural groundwater contaminants together with the growing demand for irrigated food production and predicted climate change further complicate the development of strategies for using groundwater resources sustainably. We provide an introduction and overview of 11 articles, collated in this special issue, which describe the current condition of vulnerable groundwater resources across the Indian Sub-Continent.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): S.H.P.W. Gamage , G.A. Hewa , S. Beecham Study region The study is based on unregulated catchments located in Mt. Lofty, Northern and Yorke regions of South Australia (SA). Study focus Hydrological losses, which are frequently used in design flood estimation, have a wide range of spatial and temporal variability. However, the current practice for many design applications is to use a single loss value. Adopting a single representative value for loss is likely to introduce a high degree of uncertainty and potential bias. This paper identifies the relationships between losses and other parameters that can be incorporated in hydrological models to make reasonably accurate estimates of the losses. This paper assesses the variability of losses and identifies a method that can model initial loss (IL) using the parameters total rainfall (TR), rainfall duration ( D ) and antecedent wetness (AW). This study is based on 1162 rainfall events from the selected catchments. New hydrological insights for the region This paper introduces two nomographs, TR– D and TR–AW, which are implemented using k-colour maps and a central tendency method. The developed methods are then validated using the rainfall runoff model, Water Bound Network Model (WBNM). This study will yield improvements to existing loss models by utilising rainfall and antecedent data, instead of using representative values to generalise real situations.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Christine A. Rumsey , Matthew P. Miller , David D. Susong , Fred D. Tillman , David W. Anning Study region The study region encompasses the Upper Colorado River Basin (UCRB), which provides water for 40 million people and is a vital part of the water supply in the western U.S. Study focus Groundwater and surface water can be considered a single water resource and thus it is important to understand groundwater contributions to streamflow, or baseflow, within a region. Previously, quantification of baseflow using chemical mass balance at large numbers of sites was not possible because of data limitations. A new method using regression-derived daily specific conductance values with conductivity mass balance hydrograph separation allows for baseflow estimation at sites across large regions. This method was applied to estimate baseflow discharge at 229 sites across the UCRB. Subsequently, climate, soil, topography, and land cover characteristics were statistically evaluated using principal component analysis (PCA) to determine their influence on baseflow discharge. New hydrological insights for the region Results suggest that approximately half of the streamflow in the UCRB is baseflow derived from groundwater discharge to streams. Higher baseflow yields typically occur in upper elevation areas of the UCRB. PCA identified precipitation, snow, sand content of soils, elevation, land surface slope, percent grasslands, and percent natural barren lands as being positively correlated with baseflow yield; whereas temperature, potential evapotranspiration, silt and clay content of soils, percent agriculture, and percent shrublands were negatively correlated with baseflow yield.

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: March 2015 Source: Journal of Hydrology: Regional Studies, Volume 3, Supplement 1

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): B. Mehdi , R. Ludwig , B. Lehner Study region Bavaria, Germany. Study focus The Altmühl River is prone to nutrient inputs from agricultural activities. Quantifying nitrate nitrogen (NO 3 − -N) and total phosphorus (TP) concentrations due to potential future changes in the watershed is necessary for managing water quality and adhering to water policy directives. The Soil and Water Assessment Tool (SWAT) was used to provide stakeholders with support in determining the impacts of climate change (CC) in combination with crop land use change (LUC) scenarios on streamflow, NO 3 − -N and TP to the 2050 time horizon. The CC simulations stemmed from RCMs and the LUC scenarios were developed with stakeholders. New hydrological insights for the region When CC was combined with LUC, mean annual NO 3 − -N loads increased 3-fold, and TP loads 8-fold, compared to the CC simulations alone. Nutrient loads were higher in several months due to the future increased annual precipitation plus the additional fertilizer input in the land use scenarios. The maize areas above the Altmühl Lake contributed greatly to TP loads, while winter wheat areas mainly contributed to NO 3 − -N loads. When CC was combined with LUC, the in-stream nutrient concentrations exceeded ministerial guidelines of 11 mg TP/L and 0.05 mgNO 3 − -N/L every month at the outlet. CC simulations combined with LUC scenarios demonstrated non-linear dynamics whereby the direction and the magnitude of impacts were not predictable from the individual changes alone.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Osvaldo M.R. Cabral , Humberto R. da Rocha , John H. Gash , Helber C. Freitas , Marcos A.V. Ligo Study region The area of woodland savanna (cerrado) is located in southeast Brazil (21°36′ to 44′ S, 47°34′ to 41′ W). Study focus The cerrado sensu-stricto savanna evapotranspiration was observed using the eddy-covariance method over three years. New hydrological insights for the region The first year total rainfall ( R = 1664 mm) was 11% above the long-term rainfall (1498 mm) and the total evapotranspiration (ET = 1242 mm) and water equivalent of available energy ( A v = 1835 mm) were approximately 4% and 2% greater, respectively, than in the second year when the rainfall total was 5% lower than the long-term average. In the third year despite the total rainfall (1259 mm) being 24% lower than the first year and 16% lower than the average, the totals of ET (1242 mm) and A v (1815 mm) were approximately the same. The small variation in the observed annual ET totals shows that in this cerrado vegetation the deep soil moisture content supports the ET in a dry year and the water available for recharging the soil profile and groundwater (∼ R − ET) was dominated by the rainfall amount being significantly greater in the wet year (422 mm) than in the dry year (13 mm).

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Guilherme Samprogna Mohor , Daniel Andrés Rodriguez , Javier Tomasella , José Lázaro Siqueira Júnior Study region The Tapajós Basin is an important Amazon tributary affected by human activities with great potential for water conflicts. The basin, as others within the Amazon region, is receiving a number of hydropower plants, among them the Teles Pires plant, projected to operate in 2015. Study focus Hydrological impacts due to climate change affect human activities, such as hydroelectric generation, and should be carefully studied for better planning of water management. In this study, we assess climate change impacts by applying the MHD-INPE hydrological model using several climate models projections as inputs. The impact assessment consisted of statistical shifts of precipitation and discharge. Energy production in a projected hydropower plant was assessed through the development of annual power duration curves for each projection, also considering its design and structural limitations. New hydrological insights for the region The high inter-model variability in the climate projections drives a high variability in the projected hydrological impacts. Results indicate an increase of basin's sensitivity to climate change and vulnerability of water exploitation. Uncertainties prevent the identification of a singular optimal solution for impacts assessment. However, exploratory analysis of the plant design robustness for hydropower generation show a reduction in the energy production even under projections of increased discharge, due to plant capacity limitations. This is valuable information for stakeholders to decide about energy production strategies.

Description: Publication date: Available online 18 June 2015 Source: Journal of Hydrology: Regional Studies Author(s): Chandan Mahanta , Gustav Enmark , Daniel Nordborg , Ondra Sracek , Bibhash Nath , Ross T. Nickson , Roger Herbert , Gunnar Jacks , Abhijit Mukherjee , A.L. Ramanathan , Runti Choudhury , Prosun Bhattacharya Study region Arsenic enriched groundwater regime within low-industrialized Brahmaputra floodplains in Assam, NE India. Study focus We examined the origin, distribution and processes of As release by investigating the salient groundwater chemistry and subsurface sedimentological characteristics. Besides collection of groundwater samples from domestic and public water supply wells, sediment samples from boreholes were investigated for textural and colour linkages. New hydrological insights for the region Arsenic concentrations above the WHO guideline value of 10 μg/L were present in 33 wells and above the previous Indian national drinking standard of 50 μg/L were present in 15 wells. The green-olive colour sediments were more likely to yield As-enriched groundwater. The supersaturation of groundwater with respect to Fe(II) minerals, such as siderite and vivianite, explained the poor correlation between dissolved As and Fe. The result reinforced the phenomenon of reductive dissolution of Fe(III) oxyhydroxides releasing As to groundwater. This study throws light on the processes and mechanisms involved with As release in groundwater. The homogenous floodplain terrain makes the hydrological As imprint unambiguous and the hydrogeological signatures untarnished. Considering the absence of anthropogenic sources in the study area, the conclusions on the nature and causes for As release to groundwater looked dependable although the final contamination at specific subsurface sites would be influenced by advection–dispersion of groundwater flow accompanied by retardation, ion exchange, surface complexation and possible biodegradation.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Lívia Cristina Pinto Dias , Márcia N. Macedo , Marcos Heil Costa , Michael T. Coe , Christopher Neill Study region Upper Xingu River Basin, southeastern Amazonia. Study focus This study assessed the influence of land cover changes on evapotranspiration and streamflow in small catchments in the Upper Xingu River Basin (Mato Grosso state, Brazil). Streamflow was measured in catchments with uniform land use for September 1, 2008 to August 31, 2010. We used models to simulate evapotranspiration and streamflow for the four most common land cover types found in the Upper Xingu: tropical forest, cerrado (savanna), pasture, and soybean croplands. We used INLAND to perform single point simulations considering tropical rainforest, cerrado and pasturelands, and AgroIBIS for croplands. New hydrological insights for the region Converting natural vegetation to agriculture substantially modifies evapotranspiration and streamflow in small catchments. Measured mean streamflow in soy catchments was about three times greater than that of forest catchments, while the mean annual amplitude of flow in soy catchments was more than twice that of forest catchments. Simulated mean annual evapotranspiration was 39% lower in agricultural ecosystems (pasture and soybean cropland) than in natural ecosystems (tropical rainforest and cerrado). Observed and simulated mean annual streamflows in agricultural ecosystems were more than 100% higher than in natural ecosystems. The accuracy of the simulations was improved by using field-measured soil hydraulic properties. The inclusion of local measurements of key soil parameters is likely to improve hydrological simulations in other tropical regions.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Samuel Beskow , Tamara L. Caldeira , Carlos Rogério de Mello , Lessandro C. Faria , Hugo Alexandre S. Guedes Study region The study was conducted in the Rio Grande do Sul state – Brazil. Study focus Studies about heavy rainfall events are crucial for proper flood management in river basins and for the design of hydraulic infrastructure. In Brazil, the lack of runoff monitoring is evident, therefore, designers commonly use rainfall intensity–duration–frequency (IDF) relationships to derive streamflow-related information. In order to aid the adjustment of IDF relationships, the probabilistic modeling of extreme rainfall is often employed. The objective of this study was to evaluate whether the GEV and Kappa multiparameter probability distributions have more satisfying performance than traditional two-parameter distributions such as Gumbel and Log-Normal in the modeling of extreme rainfall events in southern Brazil. Such distributions were adjusted by the L-moments method and the goodness-of-fit was verified by the Kolmogorov–Smirnov, Chi-Square, Filliben and Anderson–Darling tests. New hydrological insights for the region The Anderson–Darling and Filliben tests were the most restrictive in this study. Based on the Anderson–Darling test, it was found that the Kappa distribution presented the best performance, followed by the GEV. This finding provides evidence that these multiparameter distributions result, for the region of study, in greater accuracy for the generation of intensity–duration–frequency curves and the prediction of peak streamflows and design hydrographs. As a result, this finding can support the design of hydraulic structures and flood management in river basins.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Dan Yan , Saskia E. Werners , Fulco Ludwig , He Qing Huang Study region The Pearl River, located in the south of China, is the second largest river in China in terms of streamflow. Study focus The study aims to assess the impact of climate change on seasonal discharge and extreme flows. For the assessment we use the variable infiltration capacity (VIC) model driven by bias-corrected results of five different climate models under the IPCC scenarios RCP4.5 and 8.5. New hydrological insights for the region Previous studies focussed on annual discharge and extreme flood events in the basin. However it is also important to assess variations in low flow across the basin, because it is suffering from water shortage and salt water intrusion in the dry season. Results indicate a reduction in average low flow under the five climate models. The reduction varies across the basin and is between 6 and 48% for RCP4.5. River discharge in the dry season is projected to decrease throughout the basin. In the wet season, river discharge tends to increase in the middle and lower reaches and decrease in the upper reach of the Pearl River basin. The variation of river discharge is likely to aggravate water stress. Especially the reduction of low flow is problematic as already now the basin experiences temporary water shortages in the delta.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): D.A. Hughes , A. Slaughter Study region Selected countries in southern Africa. Study focus The study uses a combination of a monthly rainfall-runoff model and a daily rainfall based disaggregation method to simulate daily flows. The two models were forced with different rainfall data (local and global) and the results examined to determine the major reasons for modelling success or failure. New hydrological insights for the region There are substantial regional differences in the success of the monthly hydrological model, which inevitably affects the success of the daily disaggregation results. There are also regional differences in the success of using global rainfall data sets (Climatic Research Unit (CRU) datasets for monthly, National Oceanic and Atmospheric Administration African Rainfall Climatology, version 2 (ARC2) satellite data for daily). The overall conclusion is that the disaggregation method presents a parsimonious approach to generating daily flow simulations from existing monthly simulations and that these daily flows are likely to be useful for some purposes (e.g. water quality modelling), but less so for others (e.g. peak flow analysis).

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): S.M. Crooks , A.L. Kay Study region The Thames catchment in southern England, UK. Study focus Modelling with 124 years of rainfall, potential evaporation (PE), temperature and naturalised flow data. Daily rainfall-runoff flow simulation using current and three historic land cover scenarios to determine the stationarity of catchment response examined through three time-frames of analysis – annual, seasonal and flow extremes. The criterion of response stationarity is often assumed in climate change impact studies. New hydrological insights The generally close correspondence between observed and simulated flows using the same model parameter values for the whole period is indicative of the temporal stability of hydrological processes and catchment response, and the quality of the hydrometric data. Changes that have occurred are a decrease in flood peak response times, typically two to three days pre and post the early 1940s, from change in agricultural practices and channel conveyance, and an increase of about 15% in summer flow from increase in urban land cover between the first decade of the 20th and 21st centuries. The water balance was found to be sensitive to the PE data used, with care needed to avoid discontinuity between two parts of the data record using different methods for calculation. Long-term mean annual rainfall shows little change but contrasting patterns of variation in seasonal rainfall demonstrate a variable climate for which simulated flow is similar to observed flow.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Dagbegnon Clement Sohoulande Djebou Study region The Niger River Basin in West Africa. Study focus The paper reports an integrated approach capable to elucidate impacts of environmental degradation on streamflow and precipitation at the watershed scale. The approach combines trends and spatial analyses of long-term streamflow, precipitation, and leaf area index LAI. Specifically, I target the Niger River Basin, then I consider monthly precipitation series over the catchment. I also consider data from 8 streamgages selected along the river. New hydrological insights for the region Over the period 1961–2012, I conduct a change point analysis of the streamflow and report two sub-periods 1961–1982 and 1983–2012. A comparison of precipitation and streamflow during these two time-slices shows meaningful changes. I describe a Kernel density analysis of streamflow and yield a probabilistic estimate of discharge anomalies along the river. Later, I evaluate seasonal trends of precipitation and streamflow. The analyses bring out critical alterations in time and space. However, these alterations seem to foreshadow critical environmental degradations occurring across the watershed. I consider LAI series derived from MODIS images, then I examine and discuss trends in land-cover dynamics in relation with the patterns in precipitation and streamflow. This late analytical step yields a holistic picture of the ongoing alterations in the Niger River Basin. Finally, I emphasize suggestions, valuable for a comprehensive water resources and environment management.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Simon Nadeau, Eric Rosa, Vincent Cloutier, Robert-André Daigneault, Jean Veillette Study region Part of Abitibi-Témiscamingue in northwestern Quebec (25,750 km 2 ), within the Quebec/Ontario Clay Belt, Canada. Study focus The focus is set on the unconfined granular aquifers found in eskers, the latter containing significant groundwater resources, both in terms of water quality and quantity. Yet, these glaciofluvial deposits also constitute the main source of exploitable sand and gravel and are therefore frequently at the roots of land use conflicts. New hydrological insights Methods and indices based on the use of geographic information systems (GIS) were developed in support of land management strategies oriented towards the protection of groundwater resources in eskers of northwestern Quebec. A groundwater resource sensitivity index was defined for each 10 × 10 m parcel of esker on the basis of (1) an evaluation of the aquifer potential based on three geomorphological parameters observable on well-known granular aquifers and (2) estimates of the parameters included in the DRASTIC method. The pressure induced by sand and gravel extraction on the groundwater resources was subsequently evaluated on the basis of (1) the resource sensitivity index, and (2) the spatial density of sand and gravel extraction sites and groundwater wells. These calculations are used to suggest solutions for supporting the sustainable management of sand and gravel extraction activities at the regional scale and for highlighting sectors where field data acquisition is most needed.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Magali Troin, Daniel Caya, Juan Alberto Velázquez, François Brissette Study region An analysis of hydrological response to a dynamically downscaled multi-member multi-model global climate model (GCM) ensemble of simulations based on the Canadian Regional Climate Model (CRCM) is presented for three snowmelt-dominated basins in Canada. The basins are situated in the western mountainous (British Columbia) and eastern level (Quebec) regions in Canada, providing comprehensive experiments to validate the CRCM over various topographic features. Study focus The evaluation of the CRCM as a tool to improve GCM simulations of catchment scale hydrology is investigated within the bounds of uncertainty associated with RCM simulations. Daily climate variables were extracted from a 30-year CRCM and GCM ensemble simulations. The hydrological response was assessed through the comparison of catchment water components simulated by SWAT. New hydrological insights for the region Results show that the CRCM captures the primary features of observed climate, but there are significant biases. Most noteworthy are a positive bias in precipitation and a negative bias in temperature over the BC basin. When looking at the hydrological modeling results, the benefit of using the RCM versus GCMs emerged distinctly for the mountainous BC basin where the RCM is preferred over the GCMs. The sensitivity experiments show that uncertainty in the GCM/RCM’s internal variability must be assessed to provide suitable regional hydrological responses to climate change.

Description: Publication date: Available online 6 October 2015 Source: Journal of Hydrology: Regional Studies Author(s): Shannon Holding, Diana M. Allen, Chelsea Notte, Nancy Olewiler Study region This study is based in the rapidly developing shale gas region of Northeast British Columbia, Canada. Study focus Water security is central to decision-making within a water–energy nexus. In areas where energy resources, such as shale gas, are undergoing rapid development, water security and the associated risks to water quality and quantity are of paramount concern. However, in many regions there is a lack of understanding and data on the hydrologic system, particularly its vulnerability to hazards. The data and knowledge gap poses challenges for effective regulation of the shale gas activities and management of water resources. This paper describes initiatives that are addressing concerns surrounding water security in Northeast British Columbia. New hydrological insights for the region Initiatives and tools enhancing water security in the region include strategic partnerships and stakeholder collaborations, policy and regulation development, and data collection and distribution efforts. The contributions and limitations of each of these are discussed. A vulnerability mapping framework is presented which addresses data gaps and provides a tool for decision-making surrounding risk to water quality from various hazards. An example vulnerability assessment was conducted for wastewater transport along pipeline and trucking corridors.

Description: Publication date: Available online 21 December 2015 Source: Journal of Hydrology: Regional Studies Author(s): Karen Ann B. Jago-on, Fernando P. Siringan, Rosana Balangue-Tarriela, Makoto Taniguchi, Yvette Kirsten Reyes, Ronald Lloren, Maria Angelica Peña, Elenito Bagalihog Study region Calamba and Los Baños in Laguna Province, Philippines lie between the northern part of Mt. Makiling and north shore of Laguna de Bay. Study focus One significant activity in Laguna province is the development of the water resorts which includes hot springs resorts and spas. Presence of hot springs is due to the geothermal activities in the area. This study seeks to explore the nature and possible impacts of groundwater utilization in hot spring resorts in Calamba and Los Baños in Laguna Province. This study also analyzes the issues and challenges in the implementation of policies and laws to regulate water use in these resorts. New hydrological insights for the region These water resorts are estimated to consume large volume of groundwater which could result to over-extraction and decrease in groundwater quantity. However, monitoring and regulation of usage is difficult as most of these resorts operate without water use permits. If groundwater use is left unregulated, water availability for the resorts industry and for domestic, commercial and other uses in the future will be negatively affected. It is necessary to strengthen implementation of laws and enhance partnerships among national and local government agencies, private sector, civil society and communities, in the proper monitoring and regulation of groundwater resources to promote sustainability.

Description: Publication date: March 2016 Source: Journal of Hydrology: Regional Studies, Volume 5 Author(s): Kathleen Rugel, Stephen W. Golladay, C. Rhett Jackson, Todd C. Rasmussen Study region Karst watershed in Lower Flint River Basin (LFRB), southwestern Georgia, USA. Study focus Baseflow discharges in the LFRB have declined for three decades as regional irrigation has increased; yet, the location and nature of connectivity between groundwater and surface water in this karstic region are poorly understood. Because growing water demands will likely be met by further development of regional aquifers, an important management concern is the nature of interactions between groundwater and surface water components under natural and anthropogenic perturbations. We conducted coarse and fine-scale stream sampling on a major tributary of the Lower Flint River (Ichawaynochaway Creek) in southwestern Georgia, USA, to identify locations and patterns of enhanced hydrologic connectivity between this stream and the Upper Floridan Aquifer. New hydrological insights for the region: Prior water resource studies in the LFRB were based on regional modeling that neglected local heterogeneities in groundwater/surface water connectivity. Our results demonstrated groundwater inputs were concentrated around five of fifty sampled reaches, evidenced by increases in multiple groundwater indicators at these sites. These five reaches contributed up to 42% of the groundwater detected along the entire 50-km sampling section, with ∼24% entering through one groundwater-dominated tributary, Chickasawhatchee Creek. Intermittent flows occurred in two of these upstream reaches during extreme drought and heavy groundwater pumping, suggesting reach-scale behaviors should be considered in resource management and policy.

Description: Publication date: March 2016 Source: Journal of Hydrology: Regional Studies, Volume 5 Author(s): Junfeng Liu, Rensheng Chen Study region Hulugou River Basin (HRB) of Qilian Mountains, eastern edge of Tibetan Plateau. Study focus Traditional manual observations only record point-scale precipitation rather than regional-scale precipitation. Automatic weather stations just record precipitation amount without discriminating by type of precipitation. This study observed precipitation types all over the HRB and analyzed air temperature and humidity conditions at daily and half-hour resolution. New hydrological insights for the region Combined observations of air temperature and precipitation type indicate that, at daily resolution the threshold air temperature between rain and snow is 0 °C and the air temperature at rain/snow boundary is from 0 °C to 7.6 °C, which means the rain and mixed precipitation threshold air temperature can shift more than 7.0 °C in the HRB. At half-hour resolution, air temperature is above 0 °C during rainfall, under 0 °C for snowfall, and above 0 °C at the rain/snow precipitation boundary, and could either be above 0 °C or fluctuate around 0 °C for mixed precipitation. Corresponding relative humidity observations indicate that rainfall and mixed precipitation events correspond with high humidity conditions in warm season of the HRB. Snowfall events correspond with low humidity conditions in the HRB.

Description: Publication date: Available online 28 November 2015 Source: Journal of Hydrology: Regional Studies Author(s): Fei Tian, Yi He Lü, Bo Jie Fu, Yong Hui Yang, GuoYu Qiu, Chuanfu Zang, Lu Zhang Study region The Qilian Mountain, northwestern China. Study focus Land degradation is a global eco-environmental issue. To minimize soil erosion and land degradation, China has implemented several ecological engineering such as “Grain for Green” program (GFG) since 1999. Relationship between vegetation and water budgets in catchments has been widely studied, however very few studies addressed the effects of eco-environmental restoration on water balance in mountain areas, especially with a focus on soil moisture content. Therefore SWAT model was used to quantify the effects of ecological engineering actions (taken place in 2005) on water balance in Qilian Mountain. New hydrological insights for the region After the ecological engineering, water yield and soil water content experienced an increment of 32%, and 46%. The opposite trend was monitored in runoff and evapotranspiration, which decreased by 48% and 4%, respectively. Therefore ecosystem restoration have increased soil water retention capacity, a greater proportion of precipitation reaching the catchment is absorbed by the soil rather than flowing out of the region as runoff. Therefore trade-offs between environmental sustainability and water resources security should be carefully addressed in arid region that experienced severe water shortages.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Leanne K. Morgan, Adrian D. Werner Study region Twenty-eight coastal aquifer case study areas across Australia. Study focus Seawater intrusion causes degradation of groundwater resources in coastal areas. The characterization of seawater intrusion is difficult and expensive, and there is therefore a need to develop methods for rapid assessment of seawater intrusion as part of large-scale screening studies in order to guide future investment. We use a steady-state analytic approach to quantify seawater extent and propensity for change in seawater extent under different stresses, in combination with findings from a previous qualitative investigation, which relies on a data-based assessment of regional trends. New hydrological insights for the region The combination of methods identified areas of highest risk to SWI including unconfined aquifers at Derby (WA) and Esperance (WA), and confined aquifers at Esperance (WA) and Adelaide (SA). The combination of analytic and qualitative approaches offers a more comprehensive and less subjective seawater intrusion characterization than arises from applying the methods in isolation, thereby imparting enhanced confidence in the outcomes. Importantly, active seawater intrusion conditions occur in many of Australia’s confined coastal aquifers, obviating the use of the analytical solution, and suggesting that offshore groundwater resources provide significant contributions to these systems.

Description: Publication date: Available online 2 December 2015 Source: Journal of Hydrology: Regional Studies Author(s): Kimberly Burnett, Christopher Wada, Aiko Endo, Makoto Taniguchi Study region Obama City has a population of 33,000 and is located in the central Wakasa district, in southwest Fukui Prefecture, Japan. Obama’s groundwater resources are supported by the Kitagawa (38 km 2 ) and Miniamigawa (17 km 2 ) river basins. Groundwater is used aboveground year round for commercial and domestic purposes and during winter months to melt snow. Submarine groundwater discharge along the coast supports a nearshore fishery in the region. Study focus Results from a choice-based analysis suggest that residents are willing to pay on average JPY 565 per month to maintain the drinking water function and aquatic resource function of groundwater in the Fukui region. However, the static approach is not appropriate for estimating the net present value of the resource, i.e., the discounted net benefit aggregated over time. We therefore develop and propose a dynamic framework capable of assessing tradeoffs between the various water uses as scarcity increases or decreases in the future. New hydrological insights for the region Marginal willingness to pay for water in Obama is currently low because freshwater is abundant. We expect that future optimal water extraction patterns will depend most on trends in energy costs, climate change and demand growth.

Description: Publication date: March 2016 Source: Journal of Hydrology: Regional Studies, Volume 5 Author(s): P. Möller, E. Rosenthal, N. Inbar, F. Magri Study region Yizre’el-Harod-Bet She’an valley, Lower Galilee and Golan Heights, Israel. Study focus Identification of pure groundwater that infiltrated the widespread alkali olivine basalts in the replenishment areas of the study region. New hydrological insights for the region The groundwater is characterized by equivalent ratios such as Na/Cl > 1; Na/HCO 3 − 〈 1; SO 4 2− -fraction 〈 0.1; HCO 3 − /(Ca + Mg + Na) ≥ 0.7; HCO3 − /(Ca + Mg) > 1; 1000Br/Cl in the range of 1–2.5; δ 34 S sulfate 〈 5‰ (CDT). Bowl-shaped-normalized REY distribution patterns are indicative for recharge over basaltic outcrops. These aquifers are recharged not only by direct precipitation on volcanic exposures but also by water from underlying confined limestone aquifers. Groundwater from the limestone aquifers is characterized by Na/Cl 〈 1; HCO 3 − /(Ca + Mg) 〈 1; HCO 3 − /(Ca + Mg + Na) 〈 0.7; 1000Br/Cl in the range of 1.6–10; δ 34 S sulfate range from 20 to 25‰ (CDT). The wide spread of these parameters characterizes mixing of groundwater from both limestone catchments and aquifers in different stages of hydochemical evolution. The REY patterns of these groundwaters resemble those of limestones. If δ 34 S sulfate and/or REY distribution patterns are not available, the unmixed water from basaltic-rock aquifers show up in the field of HCO 3 − /(Ca + Mg) > 1 and HCO 3 − /(Ca + Mg + Na + K) > 0.7. Application of these parameters to analyses showing only the main constituents of groundwater reveals that in the study area the contribution of unmixed groundwater from basaltic catchments is largely restricted to the Golan Heights. Mixing of groundwater by interaquifer flow is a common phenomenon all over the area. Graphical abstract

Description: Publication date: Available online 26 November 2015 Source: Journal of Hydrology: Regional Studies Author(s): Allen D. Roberts Study region This study investigated impacts of current landscape configuration on streamflow within selected small watersheds of the Atlanta, Georgia metropolitan region (AMR). Study focus To determine effects of current landscape arrangement on watershed-wide Hydrologic Unit Code (HUC)-12 land cover/land use (LC/LU), the configurational metric of contagion was chosen. Contagion-adjusted curve numbers (CNs) were calculated for all 405 HUC-12 watersheds in the AMR. 6 watersheds were chosen for Thornthwaite Water Balance (TWB) model evaluation based upon having a stream gage record of the 5 year (60 month) period most closely associated with contagion and CN values derived from the 2011 National Land Cover Dataset (NLCD). 4 watersheds out-performed their original CN watershed simulations based upon: Nash–Sutcliffe efficiency (NSE); room mean square error (RMSE)-standard deviation ratio (RSR); and Akaike Information Criteria (AIC) analysis. New hydrological insights Configurational metrics related to contagion of the aggregation index ( AI ) and clumpiness index ( CI ) indicated possible reasoning to explain differences found between the 4-watershed and 2-watershed categories. The AI of agricultural LC/LU within the 2-watershed category suggested greater landscape heterogeneity due to agricultural patch disaggregation, whereas the CI suggested greater overall disaggregation and landscape dispersion for all non-water LC/LU patches within the 2-watershed category and pointed towards greater landscape heterogeneity driven by higher dispersal of non-water patches. Both may lead to complex flow patterns not easily estimated within streamflow simulations.

Description: Publication date: Available online 28 November 2015 Source: Journal of Hydrology: Regional Studies Author(s): A. Ovando, J. Tomasella, D.A. Rodriguez, J.M. Martinez, J.L. Siqueira-Junior, G.L.N. Pinto, P. Passy, P. Vauchel, L. Noriega, C. von Randow Study region The Amazonian wetlands of Bolivia, known as the Llanos de Moxos, are believed to play a crucial role in regulating the upper Madeira hydrological cycle, the most important southern tributary of the Amazon River. Because the area is vast and sparsely populated, the hydrological functioning of the wetlands is poorly known. Study focus We analyzed the hydrometeorological configurations that led to the major floods of 2007, 2008 and 2014. These data, together with flood mapping derived from remote sensing images, were used to understand the dynamics of the Llanos during the three flood events. New hydrological insights for the region The results showed that large floods are the result of the superimposition of flood waves from major sub-basins of the region. As a previous study suggested, the dynamics of the floods are controlled by an exogenous process, created by the flood wave originating in the Andes piedmont that travels through the Mamoré River; and by an endogenous process, which is the runoff originating in the Llanos. Our study showed that the first process is evident only at the initial phase of the floods, and although important for attenuating the rising flood wave, it is of lesser importance compared to the endogenous process. We conclude that the endogenous process controls the magnitude and duration of major floods.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Abraham Mechal, Thomas Wagner, Steffen Birk Study region Gidabo River Basin, located in the south eastern Main Ethiopian Rift (MER). Study focus The focus is to characterize the spatial and temporal variability of groundwater recharge, identify the drivers that govern its distribution, and to improve the understanding of its sensitivity to precipitation and temperature in the MER by applying the semi-distributed hydrological model, Soil and Water Assessment Tool (SWAT). New hydrological insights for the region The average annual recharge for 1998–2010 reveals a remarkable decrease from the highland (410 mm/year) towards the rift floor (25 mm/year). Both the spatial and temporal recharge variability is mainly controlled by the climate. In the rift floor, recharge is found to occur only when annual precipitation exceeds a threshold of approximately 800 mm. A sensitivity analysis reveals that annual recharge is very sensitive to variations in precipitation and moderately sensitive to temperature changes. The relative sensitivity increases from the highland to the rift floor across the watershed. Increases in both precipitation and temperature, as suggested by climate change projections for Ethiopia, appear to have an overall positive impact on recharge in the majority of the catchment. These findings have implications also for other catchments where recharge is spatially nonuniform and provide a basis for further investigations into the assessment of groundwater resources and their vulnerability to climate change at the watershed and sub-watershed scale.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Peirong Lin, Zong-Liang Yang, Xitian Cai, Cédric H. David Study region Lake Buchanan, a major reservoir for the City of Austin area, the Texas Hydrologic Region 12, USA. Numerical climate models are increasingly being used by climate scientists to inform water management. However, successful transitions from climate models (O(10–100 km)) to water resources studies (O(100 m–1 km)) still need improved data structures and modeling strategies to resolve spatial scale mismatch. In this study, we introduce a mechanistic lake-level modeling framework that consists of a state-of-the-art land surface model – Noah-MP, a vector-based river routing scheme – RAPID, and a lake mass-balance model. By conducting a case study for Lake Buchanan, we demonstrate the capability of the framework in predicting lake levels at seasonal lead times. The experiments take into account different runoff resolutions, model initialization months, and multiple lead times. Uncertainty analyses and sensitivity tests are also conducted to guide future research. New hydrological insights Different from traditional grid-based solutions, the framework is directly coupled on the vector-based NHDPlus dataset, which defines accurate hydrologic features such as rivers, dams, lakes and reservoirs. The resulting hybrid framework therefore allows for more flexibility in resolving “scaling-issues” between large-scale climate models and fine-scale applications. The presented hindcast results also provide insight into the influences of baseline LSM resolutions, initialization months, and lead times, which would ultimately help improve lake-level forecast skills.

Description: Publication date: September 2015 Source: Journal of Hydrology: Regional Studies, Volume 4, Part B Author(s): Kathleen Feiner, Christopher S. Lowry Study Focus This research examines a wetland environment before and after the construction of a beaver dam to determine the hydrologic impacts on regional groundwater flow and quantify changes to the capture zone of a wetland pond. Increased hydraulic head behind a newly built beaver dam can cause shifts in the capture zone of a wetland pond. Changes in groundwater flux, and the extent of both the capture and discharge zones of this wetland were examined with the use of a groundwater flow model, created using MODFLOW. New hydrological insights for the region The construction of a beaver dam resulted in minimal changes to regional groundwater flow paths at this site, which is attributed to a clay unit underlying the peat, disconnecting this wetland from regional groundwater flow. However, groundwater discharge from the wetland pond increased by 90%. Simulating a scenario with the numerical model in which the wetland is connected to regional groundwater flow results in a much larger impact on flow paths. In the absence of the clay layer, the simulated construction of a beaver dam causes a 70% increase in groundwater discharge from the wetland pond and increases the surface area of both the capture zone and the discharge zone by 30% and 80%, respectively.

Description: Publication date: Available online 8 December 2015 Source: Journal of Hydrology: Regional Studies Author(s): Eleonora M.C. Demaria, Richard N. Palmer, Joshua K. Roundy Study region Northeast and Midwest, United States. Study focus Assessing the climate change impacts on the basin scale is important for water and natural resource managers. Here, the presence of monotonic trends and changes in climate-driven simulated 3-day peak flows, 7-day low flows, and mean base flows are evaluated in the Northeast and Midwest U.S. during the 20th and the 21st centuries using climate projections from sixteen climate models. Proven statistical methods are used to spatially and temporally disaggregate precipitation and temperature fields to a finer resolution before being used as drivers for a hydrological model. New hydrological insights for the region Changes in the annual cycle of precipitation are likely to occur during the 21st century as winter precipitation increases and warmer temperatures reduce snow coverage across the entire domain especially in the northern basins. Maximum precipitation intensities are projected to become more intense across the region by mid-century especially along the coast. Positive trends in 3-day peak flows are also projected in the region as a result of the more intense precipitation, whereas the magnitude of 7-day low flows and mean base flows are projected to decrease. The length of the low flows season will likely extend by mid-century despite the increased precipitation as the atmospheric demand increases.

Description: Publication date: Available online 12 December 2015 Source: Journal of Hydrology: Regional Studies Author(s): Christina M. Richardson, Henrietta Dulai, Robert B. Whittier Study region Maunalua Bay, Oahu, Hawai’i. Study focus We examined submarine groundwater discharge (SGD), terrestrial groundwater, and nearshore marine water quality in two adjacent aquifers (Waialae East and Waialae West) with differing land-use and hydrogeologic characteristics to better understand the sources and spatial variability of SGD-conveyed nutrients. Nutrient concentrations and NO 3 − stable isotope ratios were measured and integrated with SGD flux, land-use, and recharge data to examine SGD nutrient loads and potential sources in each aquifer. New hydrological insights for the region Regionally elevated NO 3 - concentrations (166–171 μM), and δ 15 N–NO 3 − values (10.4–10.9‰) were apparent in SGD in the Waialae West Aquifer, an area with high on-site disposal system density (e.g. cesspools). Coastal sites sampled in the neighboring Waialae East Aquifer exhibited significantly lower values for these parameters, with δ 15 N–NO 3 − values ranging from 5.7–5.9‰ and NO 3 − concentrations from 43–69 μM. The isotopic composition of NO 3 − in SGD originating from the Waialae West Aquifer was consistent with wastewater. Modeled recharge data corroborated the NO 3 − stable isotope source designation. SGD emanating from Waialae West Aquifer was primarily influenced by two-component mixing of a wastewater source with low nutrient groundwater as wastewater effluent accounted for more than 4% of total recharge and 54–95% of total N and P loads in the aquifer.

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 20〈/p〉 〈p〉Author(s): J.B. Callegary, S.B. Megdal, E.M. Tapia Villaseñor, J.D. Petersen-Perlman, I. Minjárez Sosa, R. Monreal, F. Gray, F. Grijalva Noriega〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study Region〈/h6〉 〈p〉This study region encompasses the Transboundary San Pedro and Santa Cruz aquifers which are shared between the states of Sonora (Mexico) and Arizona (US). Special regional considerations include a semi-arid climate, basin-fill aquifers with predominantly montane recharge areas, economic drivers in the mining, trade, and military sectors, groundwater-dependent cities with expanding cones of depression, interbasin groundwater transfers, ground- and surface-water contamination, and protected aquatic and riparian habitats that act as significant migration corridors for hundreds of species, including some that are threatened and endangered.〈/p〉 〈/div〉 〈div〉 〈h6〉Study Focus〈/h6〉 〈p〉We focus on lessons learned from the hydrologic assessment of the Transboundary San Pedro and Santa Cruz aquifers. We conducted the work, in two phases: (1) laying the groundwork and (2) implementation. The “laying the groundwork” phase consisted of binational meetings with stakeholders and key actors (agencies and individuals), and the development of an understanding of the physical, institutional, historical, and socio-political context. This led to signing of the binational Transboundary Aquifer Assessment Program (TAAP) agreement in 2009 and detailed the process for cooperation and coordination in the assessment of shared aquifers. The implementation phase began with an agreement to proceed with the study of four “focus” aquifers (Santa Cruz, San Pedro, Mesilla (Conejos-Médanos in Mexico), and Hueco Bolson (Bolsón del Hueco in Mexico)) and development of associated technical teams. Though we do include a brief discussion of the lessons learned from the physical science portion of the study, the results have been described and published elsewhere. The bulk of the paper instead focuses on the findings and lessons learned from the integration of social-science perspectives into a largely physical-science based program, since there is a growing recognition of the need for this type of approach especially in the management and assessment of transboundary aquifers.〈/p〉 〈/div〉 〈div〉 〈h6〉New Hydrological Insights for the Region〈/h6〉 〈p〉The Sonora-Arizona effort succeeded because both countries were adequately represented, and because of flexibility of skills and ability of teams comprising both university and government scientists. Teams included social and earth scientists. Including the social sciences was critical to research design and implementation, and to addressing the cultural, institutional, and socio-political contexts of transboundary aquifer assessment. Significant components of the continuing implementation phase include strategic planning, data compilation and analysis, cross-border integration of datasets, geophysical and geochemical surveys, and internal, peer, and stakeholder engagement.〈/p〉 〈/div〉

Description: 〈p〉Publication date: August 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 18〈/p〉 〈p〉Author(s): Mark Gabriel, Christopher Knightes, Ellen Cooter, Robin Dennis〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study region〈/h6〉 〈p〉The SWAT model was used to estimate the combined effects of changing land cover, climate and Clean Air Act (CAAA)-related atmospheric nitrogen (N) deposition to watershed nitrogen fate and transport for two watersheds in North Carolina, USA.〈/p〉 〈/div〉 〈div〉 〈h6〉Study focus〈/h6〉 〈p〉Two different model simulation scenarios were applied: one included CAAA-related atmospheric N deposition, climate and land cover (CAAD + C + L) and the other only included CAAA-related N deposition (CAAD) in simulation.〈/p〉 〈/div〉 〈div〉 〈h6〉New hydrological insights for the region〈/h6〉 〈p〉Results show both scenarios generated overall decreasing trends for nearly all N outputs between 2010 and 2070 which resulted primarily from CAAA-related reductions in oxidized N deposition. In both watersheds, including climate and land cover change in simulation resulted in a relative 30% higher NO3 load, 30% higher denitrification, 10% higher organic N load and a 20% smaller level of plant N uptake in year 2070 compared to not including climate and landcover changes in simulation. The increases in N transport for both watersheds indicates the combined impacts from climate and land cover change may offset benefits provided by the CAAA regulations; however, future NO〈sub〉3〈/sub〉 loads for the Little River watershed were small relative to current N loading rates. Conversely, the increasing NO〈sub〉3〈/sub〉 and organic N loads for the nearby Nahunta watershed were significant compared to current rates demonstrating that watershed nutrient responses to climate and land cover changes may vary significantly over relatively small spatial scales.〈/p〉 〈/div〉

Description: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 20〈/p〉 〈p〉Author(s): Geert-Jan Nijsten, Greg Christelis, Karen G. Villholth, Eberhard Braune, Cheikh Bécaye Gaye〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study region〈/h6〉 〈p〉Transboundary aquifers (TBAs) of Africa.〈/p〉 〈/div〉 〈div〉 〈h6〉Study focus〈/h6〉 〈p〉Review of work on TBAs in Africa, including an overview of assessments and management efforts that have taken place over the last half century.〈/p〉 〈/div〉 〈div〉 〈h6〉New hydrological insights〈/h6〉 〈p〉Seventy-two TBAs have been mapped in Africa. They underlie 40% of the continent, where 33% of the population lives, often in arid or semi-arid regions. TBA inventories have progressed since 2000 and remain work in progress. Despite their importance only eleven TBAs have been subjected to more detailed studies. Cooperation has been formalised for seven TBAs. Most of these TBAs are in North Africa and the Sahel. The recent global Transboundary Waters Assessment Programme compiled information at the national level to describe TBAs in terms of key indicators related to the water resource, socio-economic, and legal and institutional conditions. Availability of data at national level is low, hampering regional assessment. Comparing indicators, from questionnaire surveys, with those from a global water-use model showed variable levels of agreement, calling for further research. Reports on agreements scoping TBA management, indicate that this may be dealt with within international river/lake agreements, but reported inconsistencies between TBA sharing countries also indicate that implementation is limited. Increasing awareness and support to joint TBA management is noticeable amongst international organisations. However, such cooperation requires long-term commitment to produce impacts at the local level.〈/p〉 〈/div〉

Description: 〈p〉Publication date: October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Hydrology: Regional Studies, Volume 19〈/p〉 〈p〉Author(s): Sitotaw Haile Erena, Hailu Worku, Francesco De Paola〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉 〈h6〉Study region〈/h6〉 〈p〉This study was conducted in Dire Dawa city of Ethiopia, where flood hazard occurs on regular basis.〈/p〉 〈/div〉 〈div〉 〈h6〉Study focus〈/h6〉 〈p〉The study was conducted with the aim of mapping flood hazard and exploring local flood risk management strategies. As to flood mapping, FLO-2D hydrodynamic model was employed to identify flood prone villages. FLO-2D was chosen for its versatility to use different data sources. To identify local flood management strategies, household survey was conducted on 232 households located in flood prone areas.〈/p〉 〈/div〉 〈div〉 〈h6〉New hydrological insights for the region〈/h6〉 〈p〉The final result of flood hazard map identified about 1163 buildings located inside high, medium and low flood hazard zones. The validity of the FLO-2D model versus ground truth was statistically tasted and showed a strong positive correlation. Flood smell, cloud direction, extreme weather and gunshot were identified as the locally used flood early warning strategies. Even if, the local flood risk management strategies have helped to reduce the level of vulnerability at normal condition, the gap is observed when extreme events are recorded. It is highly recommended that the flood hazard map developed for the city and existing flood management strategies are properly utilized for future flood risk planning of Dire Dawa city and its watershed.〈/p〉 〈/div〉