ALBERT

Description: Understanding the relationship between land use and surface water quality is necessary for effective water management. We estimated the impacts of catchment-wide land use on water quality during the dry and rainy seasons in the Dongjiang River basin, using remote sensing, geographic information systems and multivariate statistical techniques. The results showed that the 83 sites can be divided into three groups representing different land use types: forest, agriculture and urban. Water quality parameters exhibited significant variations between the urban-dominated and forest-dominated sites. The proportion of forested land was positively associated with dissolved oxygen concentration but negatively associated with water temperature, electrical conductivity, permanganate index, total phosphorus, total nitrogen, ammonia nitrogen, nitrate nitrogen and chlorophyll-a. The proportion of urban land was strongly positively associated with total nitrogen and ammonia nitrogen concentrations. Forested and urban land use had stronger impacts on water quality in the dry season than in the rainy season. However, agricultural land use did not have a significant impact on water quality. Our study indicates that urban land use was the key factor affecting water quality change, and limiting point-source waste discharge in urban areas during the dry season would be critical for improving water quality in the study area.

Description: The morphological properties of kaolin flocs were investigated in a Couette-flow experiment at the steady state under seven shear flow conditions (shear rates of 5.36, 9.17, 14, 24, 31, 41 and 53 s−1). These properties include a one-dimensional (1-D) fractal dimension (D1), a two-dimensional (2-D) fractal dimension (D2), a perimeter-based fractal dimension (Dpf) and an aspect ratio (AR). They were calculated based on the projected area (A), equivalent size, perimeter (P) and length (L) of the major axis of the floc determined through sample observation and an image analysis system. The parameter D2, which characterizes the relationship between the projected area and the length of the major axis using a power function, , increased from 1.73 ± 0.03, 1.72 ± 0.03, and 1.75 ± 0.04 in the low shear rate group (G = 5.36, 9.17, and 14 s−1) to 1.92 ± 0.03, 1.82 ± 0.02, 1.85 ± 0.02, and 1.81 ± 0.02 in the high shear rate group (24, 31, 41 and 53 s−1), respectively. The parameter D1 characterizes the relationship between the perimeter and length of the major axis by the function  and decreased from 1.52 ± 0.02, 1.48 ± 0.02, 1.55 ± 0.02, and 1.63 ± 0.02 in the low shear group (5.36, 9.17, 14 and 24 s−1) to 1.45 ± 0.02, 1.39 ± 0.02, and 1.39 ± 0.02 in the high shear group (31, 41 and 53 s−1), respectively. The results indicate that with increasing shear rates, the flocs become less elongated and that their boundary lines become tighter and more regular, caused by more breakages and possible restructurings of the flocs. The parameter Dpf, which is related to the perimeter and the projected area through the function , decreased as the shear rate increased almost linearly. The parameter AR, which is the ratio of the length of the major axis and equivalent diameter, decreased from 1.56, 1.59, 1.53 and 1.51 in the low shear rate group to 1.43, 1.47 and 1.48 in the high shear rate group. These changes in Dpf and AR show that the flocs become less convoluted and more symmetrical and that their boundaries become smoother and more regular in the high shear rate group than in the low shear rate group due to breakage and possible restructuring processes. To assess the effects of electrolyte and sediment concentration, 0.1 mol/L calcium chloride (CaCl2) and initial sediment concentration from 7.87 × 10−5 to 1.57 × 10−5 were used in this preliminary study. The addition of electrolyte and increasing sediment concentration could produce more symmetrical flocs with less convoluted and simpler boundaries. In addition, some new information on the temporal variation of the median size of the flocs during the flocculation process is presented.

Description: A model for simulating vertical water level fluctuations with coupled liquid and gas phases is presented. The Preissmann implicit scheme is used to linearize the governing equations for one-dimensional transient flow for both liquid and gas phases, and the linear system is solved using the chasing method. Some classical cases for single liquid and gas phase transients in pipelines and networks are studied to verify that the proposed methods are accurate and reliable. The implicit scheme is extended using a dynamic mesh to simulate the water level fluctuations in a U-tube and an open surge tank without consideration of the gas phase. Methods of coupling liquid and gas phases are presented and used for studying the transient process and interaction between the phases, for gas phase limited in a chamber and gas phase transported in a pipeline. In particular, two other simplified models, one neglecting the effect of the gas phase on the liquid phase and the other one coupling the liquid and gas phases asynchronously, are proposed. The numerical results indicate that the asynchronous model performs better, and are finally applied to a hydropower station with surge tanks and air shafts to simulate the water level fluctuations and air speed.

Description: Free acidity of aqueous solutions was initially defined in 1909 by Søren Peter Lauritz Sørensen as pH = −lgcH+ (c/mol·dm−3 or m/mol·kg−1 of the free hydrogen ions in solution, H+) soon (1910) was changed to pH = paH+ = −lgaH+, integrating the new concepts of activity, ai and activity coefficient γi, for the ionic species i under concern, H+ in this case; it is ai = −lg(miγi). Since individual ions do not exist alone in solution, primary pH values cannot be assigned solely by experimental measurements, requiring extra thermodynamic model assumptions for the activity coefficient, γH+, which has put pH in a unique situation of not being fully traceable to the International System of Units (SI). Also the concept of activity is often not felt to be as perceptible as that of concentration which may present difficulties, namely with the interpretation of data. pH measurements on unknown samples rely on calibration of the measuring setup with adequate reference pH buffers. In this work, the assignment of pH values to buffers closely matching the samples, e.g., seawater, is revisited. An approach is presented to assess the quantity pmH+ = −lgmH+ profiting from the fact that, contrary to single ion activity coefficients, mean activity coefficients,   can be assessed based on experimentally assessed quantities alone, γExp ±, thus ensuring traceability to the mole, the SI base unit for amount of substance. Compatibility between γExp ± and mean activity coefficient calculated by means of Pitzer model equations, γPtz ±, validates the model for its intended use.

Description: Drainage networks are essential compartments in an urban infrastructure system for the efficient collection and prompt drainage of flood water. In addition to the advances in numerical techniques on urban flood simulation, the topological characteristics of urban drainage networks and their impacts on flooding have not been investigated thoroughly despite their importance. This study evaluated the urban drainage networks in Seoul, South Korea, in terms of the network configuration and its implication for peak flows and flood mitigation. Gibbs’ model was used to analyze the network configuration of 31 urban catchments with various slope ranges. The results showed that urban drainage networks can be less efficient than river in nature in terms of the drainage time, which is counter-intuitive. On the other hand, the analysis showed that efficient networks have risks of flood concentration and, hence, increase potential flood risks. This study showed that efficient networks tend to have higher peak flows at the outlet and vice versa. Therefore, an alternative drainage network layout, which is less efficient and more sinuous, was introduced and it resulted in reduced peak flows and flooding. This result shows managing a proper drainage network layout can contribute to flood mitigation in urban catchments.

Description: The main aim of this research was to improve risk mapping of heavy metals by taking account of erosion effects. A new spatiotemporal index, namely the G2met index, is introduced, with integration of pre-existing methodologies (Hakanson, EPM, and G2). The G2met index is depicted as a series of risk maps for each heavy metal on a month-time step. The southern part of Cyprus Island was selected as a study area. Concentration of major heavy metals was extracted with soil sampling in a grid of 5350 sites. Rainfall, vegetation, soil, land use, topographic, and hydrologic data were collected from existing European or global databases (WorldClim, BioBar, REDES, ESDAC, CORINE, ASTER GDEM, and USGS). A large number of regional-scale risk maps (with 500-m cell size) were created: one for each heavy metal and totally per month and annually; in addition, choropleth maps in terms of statistics per river basin were produced for every metal. Generally, the G2met maps resulted in different spatial patterns in comparison to those depicted by the Hakanson index alone.

Description: Nutrient inputs from rivers play an important role in lake eutrophication. To compare the forms characteristics of phosphorus (P) and nitrogen (N) in rivers flowing through rural and urban areas, water samples were collected seasonally from five urban rivers and six rural rivers flowing to Lake Chaohu, China. Higher total phosphorus (TP), particulate phosphorus (PP), soluble reactive phosphorus (SRP), and dissolved nonreactive phosphorus (DNP) concentrations and SRP/TP percentages were observed in urban rivers than in rural rivers, and PP/TP and DNP/TP ratios were lower in urban rivers than in rural rivers. The concentrations of total nitrogen (TN) and all N forms other than dissolved organic nitrogen (DON) were significantly higher in urban rivers than in rural rivers. NH4+/TN levels were higher in urban rivers, whereas PN/TN and DON/TN ratios were significantly lower in urban rivers compared with rural rivers. NO3−/TN and NO2−/TN levels were similar between the two groups of rivers. TP, BD-P, and NaOH-P levels in urban river surface sediments were significantly higher than those in rural rivers. NaOH-P/TP ratios were significantly elevated in urban rivers, whereas HCl-P/TP and Res-P/TP ratios were significantly lower compared with rural rivers. Urban rivers have transferred large quantities of NH4+ and SRP into Lake Chaohu, resulting in higher TP and TN levels and NH4+/TN and SRP/TP ratios. Decreasing the input of NH4+ and SRP into urban rivers is a high priority for mitigating eutrophication and algal blooms in Lake Chaohu.

Description: The limited availability of water at low prices and the current scheme for specific supply arrangements (SSA/REA), both determined at the political level, explain that the goal of being self-sufficient in terms of forage consumption is currently unattainable in the Canaries. The “PFORCA” Plan aims to counteract this reality and increase their level of self-sufficiency. The financial aid relating to the REA reduces the amount payable for the imported fodder (annual 83,000 t) versus local product, which influences the decision making by farmers. According to calculations, performed by reusing the water instead of discharging, Maralfalfa production could be competitive against imports, being financially viable with water prices in a range of 0.20–0.30 €/m3 (prices perfectly acceptable for reclaimed water with low levels of treatment, but fulfilling requirements reuse of Spanish law, RD 1620/2007). The economic contribution of forage crops could represent the creation of 640 new jobs, the enhancement of land currently abandoned, plus an increase in Gross Domestic Product (GDP) of the archipelago on more than 23 million € (M€), product of the substitution of imports by local production. Also, it would help to save the REA’s aid (6 M€).

Description: Breaching of earthen or sandy dams/dunes by overtopping flow and waves is a complicated process with strong, unsteady flow, high sediment transport, and rapid bed changes in which the interactions between flow and morphology should not be ignored. This study presents a depth-averaged two-dimensional (2D) coupled flow and sediment transport model to investigate the flow and breaching processes with and without waves. Bed change and variable flow density are included in the flow continuity and momentum equations to consider the impacts of sediment transport. The model adopts the non-equilibrium approach for total-load sediment transport and specifies different repose angles to handle non-cohesive embankment slope avalanching. The equations are solved using an explicit finite volume method on a rectangular grid with the improved Godunov-type central upwind scheme and the nonnegative reconstruction of the water depth method to handle mixed-regime flows near the breach. The model has been tested against two sets of experimental data which show that it well simulates the flow characteristics, bed changes, and sediment transport. It is then applied to analyze flow and morphologic changes by overtopping flow with and without waves. The simulated bed change and breach cross-section shape show a significant difference if waves are considered. Erosion by flow without waves mainly occurs at the breach and is dominated by vertical erosion at the initial stage followed by the lateral erosion. With waves, the flow overtops the entire length of the dune to cause faster erosion along the entire length. Erosion mainly takes place at the upper layer at the initial stage and gradually accelerates as the height of the dune reduces and flow discharge increases, which indicates the simulated results with waves shall be further verified by physical experimental evidence.

Description: Salinization and secondary salinization often appear after irrigation with saline water. The Taklimakan Desert Highway Shelterbelt has been irrigated with saline ground water for more than ten years; however, soil salinity in the shelterbelt has not been evaluated. The objective of this study was to analyze the spatial and temporal distribution of soil moisture and salinity in the shelterbelt system. Using a non-uniform grid method, soil samples were collected every two days during one ten-day irrigation cycle in July 2014 and one day in spring, summer, and autumn. The results indicated that soil moisture declined linearly with time during the irrigation cycle. Soil moisture was greatest in the southern and eastern sections of the study area. In contrast to soil moisture, soil electrical conductivity increased from 2 to 6 days after irrigation, and then gradually decreased from 6 to 8 days after irrigation. Soil moisture was the greatest in spring and the least in summer. In contrast, soil salinity increased from spring to autumn. Long time drip-irrigation with saline groundwater increased soil salinity slightly. The soil salt content was closely associated with soil texture. The current soil salt content did not affect plant growth, however, the soil in the shelterbelt should be continuously monitored to prevent salinization in the future.

Description: In this study, the geophysical properties of the landslide-prone catchment of the Gaoping River in Taiwan were investigated using zones based on landslide history in conjunction with landslide analysis using a deterministic approach based on the TRIGRS (Transient Rainfall Infiltration and Grid-based Regional Slope-Stability) model. Typhoon Morakot in 2009 was selected as a simulation scenario to calibrate the combination of geophysical parameters in each zone before analyzing changes in the factor of safety (FS). Considering the amount of response time required for typhoons, suitable FS thresholds for landslide warnings are proposed for each town in the catchment area. Typhoon Fanapi of 2010 was used as a test scenario to verify the applicability of the FS as well as the efficacy of the cumulative rainfall thresholds derived in this study. Finally, the amount of response time provided by the FS thresholds in cases of yellow and red alerts was determined. All five of the landslide events reported by the Soil and Water Conservation Bureau were listed among the unstable sites identified in the proposed model, thereby demonstrating its effectiveness and accuracy in determining unstable areas and areas that require evacuation. These cumulative rainfall thresholds provide a valuable reference to guide disaster prevention authorities in the issuance of yellow and red alerts with the ability to reduce losses and save lives.

Description: Understanding and defining the spatial distribution of sediment deposited in reservoirs is essential not only at the design stage but also during the operation. The majority of research concerns the distribution of sediment deposition in medium and large water reservoirs. Most empirical methods do not provide satisfactory results when applied to the determination of sediment deposition in small reservoirs. Small reservoir’s volumes do not exceed 5 × 106 m3 and their capacity-inflow ratio is less than 10%. Long-term silting measurements of three small reservoirs were used to evaluate the method described by Rahmanian and Banihashemi for predicting sediment distributions in small reservoirs. Rahmanian and Banihashemi stated that their model of distribution of sediment deposition in water reservoir works well for a long duration operation. In the presented study, the silting rate was used in order to determine the long duration operation. Silting rate is a quotient of volume of the sediment deposited in the reservoir and its original volume. It was stated that when the silting rate had reached 50%, the sediment deposition in the reservoir may be described by an empirical reservoir depth shape function (RDSF).

Description: Numerical modeling has become an indispensable tool for solving various physical problems. In this context, we present a model of pollutant dispersion in natural streams for the far field case where dispersion is considered longitudinal and one-dimensional in the flow direction. The Transmission Line Matrix (TLM), which has earned a reputation as powerful and efficient numerical method, is used. The presented one-dimensional TLM model requires a minimum input data and provides a significant gain in computing time. To validate our model, the results are compared with observations and experimental data from the river Severn (UK). The results show a good agreement with experimental data. The model can be used to predict the spatiotemporal evolution of a pollutant in natural streams for effective and rapid decision-making in a case of emergency, such as accidental discharges in a stream with a dynamic similar to that of the river Severn (UK).

Description: This paper provides an overview of the Special Issue on Wastewater Treatment and Reuse: Past, Present, and Future. The papers selected for publication include advanced wastewater treatment and monitoring technologies, such as membrane bioreactors, electrochemical systems; denitrifying biofilters, and disinfection technologies. The Issue also contains articles related to best management practices of biosolids, the influence of organic matter on pathogen inactivation and nutrient removal. Collectively, the Special Issue presents an evolution of technologies, from conventional through advanced, for reliable and sustainable wastewater treatment and reuse.

Description: Analysis of the relationship between evapotranspiration (ET) and its natural and anthropogenic drivers is critical in water-limited basins such as the Nile. The spatiotemporal relationships of ET with rainfall and vegetation dynamics in the Nile Basin during 2002–2011 were analyzed using satellite-derived data. Non-parametric statistics were used to quantify ET-rainfall interactions and trends across land cover types and subbasins. We found that 65% of the study area (2.5 million km2) showed significant (p 〈 0.05) positive correlations between monthly ET and rainfall, whereas 7% showed significant negative correlations.  As expected, positive ET-rainfall correlations were observed over natural vegetation, mixed croplands/natural vegetation, and croplands, with a few subbasin-specific exceptions. In particular, irrigated croplands, wetlands and some forests exhibited negative correlations. Trend tests revealed spatial clusters of statistically significant trends in ET (6% of study area was negative; 12% positive), vegetation greenness (24% negative; 12% positive) and rainfall (11% negative; 1% positive) during 2002–2011. The Nile Delta, Ethiopian highlands and central Uganda regions showed decline in ET while central parts of Sudan, South Sudan, southwestern Ethiopia and northeastern Uganda showed increases. Except for a decline in ET in central Uganda, the detected changes in ET (both positive and negative) were not associated with corresponding changes in rainfall. Detected declines in ET in the Nile delta and Ethiopian highlands were found to be attributable to anthropogenic land degradation, while the ET decline in central Uganda is likely caused by rainfall reduction.

Description: Harmful algal blooms (HABs), harmful microorganisms (pathogens) and toxic metals represent three major agents of water quality deterioration. Water quality of three northern lakes (Sardis, Enid, and Grenada) and a central lake (Ross Barnett Reservoir) of Mississippi, USA were examined in this study. While all these lakes are heavily used for recreational purposes, the Ross Barnett Reservoir serves additionally as the primary water supply for the City of Jackson, the capital city of Mississippi. The main goal of this study was to comprehensively assess the water quality of these lakes employing field and satellite data, and evaluate the potential human and aquatic health impacts. A time-series of true color images derived from satellite data indicated that algal blooms have been a recurring phenomenon in these lakes. Cyanobacteria, the algal group that predominantly occur in freshwater and form toxic blooms, were always present in these lakes and were most abundant on many occasions. The most toxic cyanotoxin, microcystin-LR, was found in all lakes, and its concentrations exceeded federal drinking water guidelines for children under six years of age many times. Potential bioaccumulation and biomagnification of microcystin-LR may pose serious risk to the aquatic ecosystem and human health including adults. Nutrient measurements indicated that all four lakes were eutrophic. Among bacterial populations, total coliforms and enterococci exceeded guideline values on several occasions. Arsenic, cadmium, chromium, and lead were found in the water of all the lakes, with arsenic exceeding the guideline values at two sites in Ross Barnett Reservoir. While it is apparent from this study that these lakes face many water quality issues, data across all seasons will be required to document potential trends and to devise management strategies. Use of remote sensing technology is recommended to monitor some of the water quality parameters such as suspended particulate matter and algal blooms, especially cyanobacterial blooms.

Description: The evolution of the major achievements in water lifting devices with emphasis on the major technologies over the centuries is presented and discussed. Valuable insights into ancient water lifting technologies with their apparent characteristics of durability, adaptability, and sustainability are provided. A comparison of the relevant technological developments in several early civilizations is carried out. These technologies are the underpinning of modern achievements in water engineering. They represent the best paradigm of probing the past and facing the future. A timeline of the historical development of water pumps worldwide through the last 5500 years of the history of mankind is presented. A chronological order is followed with emphasis on the major civilizations.

Description: This study concerns the occurrence of arsenic in the groundwater system of the Cimino-Vico volcanic area (central Italy), different parts of which are currently widely used for local drinking water supply and for irrigation. The system shows a complex groundwater circulation, including a continuous basal aquifer, discontinuous perched aquifers, groundwater flows at high altitude, and local interactions with rising thermal fluids. Data on arsenic contents in 250 water samples from springs and wells and in 68 samples from rock outcrops were measured and combined with already existing information. Results highlight that arsenic concentrations of groundwater are influenced by type of aquifer, groundwater flow path, arsenic content of the aquifer rocks, and interaction with fluids rising from depth. Waters circulating in the Vico volcanics, one of the prominent rock units of the area, have high concentrations of arsenic, both for the basal and the perched aquifers. A large fraction of the waters associated with this rock unit have arsenic contents higher than 10 μg/L (82 percent for basal, 40 percent for perched). In contrast, waters circulating in the Cimino volcanics have lower arsenic contents: 30 percent of the basal and 10 percent of the perched aquifers have arsenic concentrations greater than 10 μg/L. Through an integrated approach, including leaching tests to investigate the arsenic behavior concerning the water-rock interaction and a geostatistical modeling of data, it has been possible to identify and tentatively quantify suitable water resources that have arsenic content not exceeding the quality standards for human consumption.

Description: Stream networks are highly complex systems, in which spatially complicated and temporally varying water quality patterns develop. River eutrophication is underlain by nutrient inputs across the entire stream network and is controlled by many interacting factors in an ever moving and renewing medium. These complex features must be perceived as a whole entity to control river eutrophication. The Szamos River is one of the largest tributaries of the Tisza River in Eastern Europe. It delivers high loads of nutrients and algal biomass and fundamentally influences the hydro-morphological, chemical and ecological status of the Tisza River. To improve the ecological status of the recipient river, nutrient and phytoplankton inputs from the tributary should be controlled, yet the two rivers belong to different countries, which are reluctant to harmonize management plans. This study aims at modeling trophic status of the tributary with the PhosFate nutrient emission model to outline a set of management measures that would satisfy both countries. Four management alternatives are analysed with altered landuse patterns, and management options. Each of these alternatives is evaluated against the present conditions.

Description: In contrast to non-cohesive sediments, the incipient motion of cohesive sediments is characterized by much more complex interactions between several sedimentary, biological, and chemical parameters. Thus, site-specific investigations are required to obtain information about the erosion stability of cohesive materials. This becomes even more relevant for contaminated sediments, stored in riverine sediments as a “burden of the past”, because of their remobilization potential during flood events. This article represents a twofold measuring strategy for the detection of erosion thresholds: an in situ device for determination of critical shear stresses in the field, and a laboratory approach where sediment cores are withdrawn and subsequently analyzed over depth. The combined measuring strategy was applied in the River Elbe and at selected sites of the catchment of the River Saale. The results show a great variety of erosion thresholds over depth, demonstrating the need to conduct vertical analyses, especially when addressing buried layers with contaminations. The latter is only possible in the laboratory but the in situ device revealed clear benefits in capturing the loose flocculent layer on top of the sediment that might be easily lost during sediment retrieval and transport. Consequently, it is ideal to combine both approaches for a comprehensive insight into sediment stability.

Description: The authors wish to make the following corrections to their paper [1]: [...]

Description: A new approach for flood frequency analysis based on the probability density evolution method (PDEM) is proposed. It can avoid the problem of linear limitation for flood frequency analysis in a parametric method and avoid the complex process for choosing the kernel function and window width in the nonparametric method. Based on the annual maximum peak discharge (AMPD) in 54 years from the Dalai hydrologic station which is located on the downstream of Nen River in Heilongjiang Province of China, a joint probability density function (PDF) model about AMPD is built by the PDEM. Then, the numerical simulation results of the joint PDF model are given by adopting the one-sided difference scheme which has the property of direction self-adaptive. After that, according to the relationship between the marginal function and joint PDF, the PDF of AMPD can be obtained. Finally, the PDF is integrated and the frequency curve could be achieved. The results indicate that the flood frequency curve obtained by the PDEM has a better agreement with the empirical frequency than that of the parametric method widely used at present. The method based on PDEM is an effective way for hydrologic frequency analysis.

Description: Movable weirs have been developed to address the weaknesses of conventional fixed weirs. However, the structures for riverbed protection downstream of movable weirs are designed using the criteria of fixed weirs in most cases, and these applications cause problems, such as scour and deformation of structures, due to misunderstanding the difference between different types of structures. In this study, a hydraulic experiment was conducted to examine weir type-specific hydraulic phenomena, compare hydraulic jumps and downstream flow characteristics according to different weir types, and analyze hydraulic characteristics, such as changes in water levels, velocities and energy. Additionally, to control the flow generated by a sluice gate, energy dissipators were examined herein for their effectiveness in relation to different installation locations and heights. As a result, it was found that although sluice gates generated hydraulic jumps similar to those of fixed weirs, their downstream supercritical flow increased to eventually elongate the overall hydraulic jumps. In energy dissipator installation, installation heights were found to be sensitive to energy dissipation. The most effective energy dissipator height was 10% of the downstream free surface water depth in this experiment. Based on these findings, it seems desirable to use energy dissipators to reduce energy, as such dissipators were found to be effective in reducing hydraulic jumps and protecting the riverbed under sluice gates.

Description: This paper presents a modeling application of surface runoff using the Hydrologic Modelling System (HEC-HMS). A case study was carried out for the Jianghe watershed, a typical semi-arid and sub-humid geo-climatic region in northern China. Two modeling schemes using different descriptive sub-mechanism models provided by HEC-HMS for runoff volume, direct runoff and routing (channel flow) were investigated. The modeling results were compared with historical observation data. This work shows that HEC-HMS can be a suitable modeling tool for specific situations in China. With the appropriate selection of the sub-mechanism models, HEC-HMS can be applied to various situations, including the typical semi-arid and sub-humid conditions in northern China.

Description: This study adopts rainwater harvesting systems (RWHS) into a stormwater runoff management model (SWMM) for the spatial design of capacities and quantities of rain barrel for urban flood mitigation. A simulation-optimization model is proposed for effectively identifying the optimal design. First of all, we particularly classified the characteristic zonal subregions for spatial design by using fuzzy C-means clustering with the investigated data of urban roof, land use and drainage system. In the simulation method, a series of regular spatial arrangements specification are designed by using statistical quartiles analysis for rooftop area and rainfall frequency analysis; accordingly, the corresponding reduced flooding circumstances can be simulated by SWMM. Moreover, the most effective solution for the simulation method is identified from the calculated net benefit, which is equivalent to the subtraction of the facility cost from the decreased inundation loss. It serves as the initially identified solution for the optimization model. In the optimization method, backpropagation neural network (BPNN) are first applied for developing a water level simulation model of urban drainage systems to substitute for SWMM to conform to newly considered interdisciplinary multi-objective optimization model, and a tabu search-based algorithm is used with the embedded BPNN-based SWMM to optimize the planning solution. The developed method is applied to the Zhong-He District, Taiwan. Results demonstrate that the application of tabu search and the BPNN-based simulation model into the optimization model can effectively, accurately and fast search optimal design considering economic net benefit. Furthermore, the optimized spatial rain barrel design could reduce 72% of inundation losses according to the simulated flood events.

Description: Details are given in the paper of the refinement of a three-dimensional layer integrated turbulence model and its application to a scaled physical model of a reservoir, named Hamidieh Reservoir, in Iran. The strong turbulent flows generated in this reservoir are due to the high volumes of flow diversion, with low head differences. In this paper, a refined numerical model is applied to a reservoir, associated with a dam, water intakes and sluice gates, with the aim being to investigate the flow patterns and sediment transport processes in the vicinity of such hydraulic structures. The calibration of the model is undertaken using measurements made from a scaled physical model. The numerical model is able to predict the conditions for a range of scenarios that are difficult to test in the physical model. Different scenarios are introduced to investigate the effects of various intake and sluice gate configurations, as well as their operation schemes on the flow and sediment transport processes into Hamidieh Reservoir. The results indicate that the flow velocity field in the vicinity of one of the intakes varies significantly. Moreover, the sluice gates do not appear to have any considerable effect on the suspended sediment concentrations moving through the intakes.

Description: There is growing concern about the sustainability of groundwater supplies worldwide. In many regions, desalination—the conversion of saline water to freshwater—is viewed as a way to increase water supplies and reduce pressure on overdrawn aquifers. Using data from reports, articles, interviews, a survey, and a focus group, this paper examines if, and how, the adoption of desalination technology can lead to aquifer preservation in Baja California Sur (BCS), Mexico. The paper outlines existing institutional arrangements (i.e., rules, norms, or organizations) surrounding desalination in BCS and concludes that there are currently no effective mechanisms to ensure aquifer preservation. Four mechanisms that could be implemented to improve groundwater management are identified, including: 1) integrated water-and land-use planning; 2) creation of an institute responsible for coordinated and consistent planning; 3) improved groundwater monitoring; and 4) implementation of water conservation measures prior to the adoption of desalination technology. This paper concludes that viewing water technologies, including desalination, as sociotechnical systems—i.e., a set of technological components that are embedded in complex social, political, and economic contexts—has the potential to create a more sustainable human–environment–technology relationship. By assessing desalination technology as a sociotechnical system, this study highlights the need to focus on institutional development and capacity building, especially within local water utilities and urban planning agencies.

Description: Saturation excess is a major runoff process in humid regions such as the US Northeast. Topographic index (TI) is used to simulate the pattern of runoff-contributing areas following a saturation excess runoff process. Although TI is useful to delineate saturated areas, i.e., hydrologically sensitive areas, for taking spatially distinctive actions in watersheds for improving water quality, local resource management practitioners often question its applicability to local conditions. This study introduces two methods to validate a locally revised TI in humid central New Jersey, USA. The revised TI uses soil moisture deficit instead of water table depth as the state variable in simulating the saturation excess runoff process. First, the calculated TI values were compared to the soil moisture measurements sampled in two sites in Tewksbury Township in the region to evaluate their correlations. Second, a watershed model Variable Source Load Function (VSLF) that incorporates TI was applied to the Neshanic River Watershed in the region and compared to another watershed model Soil and Water Assessment Tool (SWAT) to evaluate its capability in predicting the streamflow and its runoff and baseflow components. The positive correlations between soil moisture measurements and TI suggested TI is a good indicator of runoff-generating potential. VSLF achieves a modeling efficiency comparable to SWAT in simulating watershed hydrology. Such validation gives practitioners confidence to incorporate TI pattern into watershed management practices for improving their efficiency. The results are applicable to shallow, interflow-driven watersheds in humid regions.

Description: An indirect simulation-optimization model framework with enhanced computational efficiency and risk-based decision-making capability was developed to determine optimal total maximum daily load (TMDL) allocation under uncertainty. To convert the traditional direct simulation-optimization model into our indirect equivalent model framework, we proposed a two-step strategy: (1) application of interval regression equations derived by a Bayesian recursive regression tree (BRRT v2) algorithm, which approximates the original hydrodynamic and water-quality simulation models and accurately quantifies the inherent nonlinear relationship between nutrient load reductions and the credible interval of algal biomass with a given confidence interval; and (2) incorporation of the calibrated interval regression equations into an uncertain optimization framework, which is further converted to our indirect equivalent framework by the enhanced-interval linear programming (EILP) method and provides approximate-optimal solutions at various risk levels. The proposed strategy was applied to the Swift Creek Reservoir’s nutrient TMDL allocation (Chesterfield County, VA) to identify the minimum nutrient load allocations required from eight sub-watersheds to ensure compliance with user-specified chlorophyll criteria. Our results indicated that the BRRT-EILP model could identify critical sub-watersheds faster than the traditional one and requires lower reduction of nutrient loadings compared to traditional stochastic simulation and trial-and-error (TAE) approaches. This suggests that our proposed framework performs better in optimal TMDL development compared to the traditional simulation-optimization models and provides extreme and non-extreme tradeoff analysis under uncertainty for risk-based decision making.

Description: This study analyzed the farmer-perceived importance of adaptation practices to climate change and examined the barriers that impede adaptation. Perceptions about causes and effects of long-term changes in climatic variables were also investigated. A total of 100 farmer-households were randomly selected from four communities in the Lawra district of Ghana. Data was collected using semi-structured questionnaires and focus group discussions (FGDs). The results showed that 87% of respondents perceived a decrease in rainfall amount, while 82% perceived an increase in temperature over the past 10 years. The study revealed that adaptation was largely in response to dry spells and droughts (93.2%) rather than floods. About 67% of respondents have adjusted their farming activities in response to climate change. Empirical results of the weighted average index analysis showed that farmers ranked improved crop varieties and irrigation as the most important adaptation measures. It also revealed that farmers lacked the capacity to implement the highly ranked adaptation practices. The problem confrontation index analysis showed that unpredictable weather, high cost of farm inputs, limited access to weather information, and lack of water resources were the most critical barriers to adaptation. This analysis of adaptation practices and constraints at farmer level will help facilitate government policy formulation and implementation.

Description: A new approach is investigated utilizing light guidance capabilities of optical pure quartz glass in order to maximize drinking water disinfection efficiency with UVC-light-emitting diodes (LEDs). Two experimental setups consisting of soda-lime AR® glass (VWR, Darmstadt, Germany) or HSQ® 100 quartz glass (Heraeus, Wasserburg, Germany) reactors were designed to compare disinfection rates with and without total reflection of UVC radiation along the reactor walls. Each reactor was filled with 9 mL bacteria samples containing either E. coli DSM (Deutsche Sammlung von Mikroorganismen) 498 or B. subtilis DSM 402 strains (concentration 1–3 × 106 colony forming units (CFU)/mL) with and without additional mixing and irradiation periods of 10, 40, and 90 s. Disinfection rates were increased up to 0.95 log10 (E. coli) and 0.75 log10 (B. subtilis) by the light guide approach in stagnant samples. The same experiments with mixing of the samples resulted in an increased disinfection efficiency of 3.07 log10 (E. coli) and 1.59 log10 (B. subtilis). Optical calculations determine that total reflection is achieved with the applied UVC-LED’s viewing angle of 15°. Furthermore measurements show that HSQ® 100 quartz has a transmittance of 92% at 280 nm UVC irradiation compared to the transmittance of soda-lime glass of 2% (1 mm wall thickness).

Description: Spatial variability plays an important role in nonlinear hydrologic processes. Due to the limitation of computational efficiency and data resolution, subgrid variability is usually assumed to be uniform for most grid-based rainfall-runoff models, which leads to the scale-dependence of model performances. In this paper, the scale effect on the Grid-Xinanjiang model was examined. The bias of the estimation of precipitation, runoff, evapotranspiration and soil moisture at the different grid scales, along with the scale-dependence of the effective parameters, highlights the importance of well representing the subgrid variability. This paper presents a subgrid parameterization method to incorporate the subgrid variability of the soil storage capacity, which is a key variable that controls runoff generation and partitioning in the Grid-Xinanjiang model. In light of the similar spatial pattern and physical basis, the soil storage capacity is correlated with the topographic index, whose spatial distribution can more readily be measured. A beta distribution is introduced to represent the spatial distribution of the soil storage capacity within the grid. The results derived from the Yanduhe Basin show that the proposed subgrid parameterization method can effectively correct the watershed soil storage capacity curve. Compared to the original Grid-Xinanjiang model, the model performances are quite consistent at the different grid scales when the subgrid variability is incorporated. This subgrid parameterization method reduces the recalibration necessity when the Digital Elevation Model (DEM) resolution is changed. Moreover, it improves the potential for the application of the distributed model in the ungauged basin.

Description: Water scarcity is the most critical constraint for sustainable cotton production in Xinjiang Province, northwest China. Drip irrigation under mulch is a major water-saving irrigation method that has been widely practiced for cotton production in Xinjiang. The performance of such an irrigation system should be evaluated for proper design and management. Therefore, a field experiment and a simulation study were conducted to (1) determine a modeling approach that can be applied to manage drip irrigation under mulch for cotton production in this region; and (2) examine the effects of irrigation amount and mulch on soil water distribution and root zone water balance components. In the experiment, four irrigation treatments were used: T1, 166.5 m3; T2, 140.4 m3; T3, 115.4 m3; and T4: 102.3 m3. The HYDRUS-2D model was calibrated, validated, and applied with the data obtained in this experiment. Soil water balance in the 0–70 cm soil profile was simulated. Results indicate that the observed soil water content and the simulated results obtained with HYDRUS-2D are in good agreement. The radius of the wetting pattern, root water uptake, and evaporation decreased as the amount of irrigation was reduced from T1 to T4, while a lot of stored soil water in the root zone was utilized and a huge amount of water was recharged from the layer below 70 cm to compensate for the decrease in irrigation amount. Mulch significantly reduced evaporation by 11.7 mm and increased root water uptake by 11.2 mm. Our simulation study suggests that this model can be applied to provide assistance in designing drip irrigation systems and developing irrigation strategies.

Description: The melting of alpine snow and glaciers is an important hydrologic process on Mount Gongga, China. The relevance of ice-snow melt to the groundwater recharge in the glacierized Hailuogou watershed is so far not well known. To better understand the origin of groundwater and the hydrological interactions between groundwater, meltwater, and precipitation in this region, 148 environmental isotopic data of water samples were analyzed for changes in isotopic composition. The results indicate that the groundwater contains a uniform isotopic signature, with δ18O values between −13.5‰ and −11.1‰ and δ2H values between −90‰ and −75‰. The mean stable isotopic composition of groundwater is heavier than that of ice-snow meltwater but lighter than that of precipitation. The effect of evaporation on the isotopic variation of groundwater is very limited and the seasonal isotope variations in precipitation are attenuated in groundwater. A model based on the δ18O results suggests that approximately 35% of the groundwater is derived from ice-snow meltwater sources. The study demonstrates that ice-snow meltwater is a substantial source of shallow groundwater in the alpine regions on the edge of the Tibetan Plateau.

Description: The water-management model used in Cape Verde for irrigation water is a singular one involving both public and private institutions. The institutional framework adopted since independence (1975) includes influences of both Portuguese colonial occupation and African culture. Water is a common-pool resource, which can take the form of communal, private or state property, or not be subject to any form of ownership. Thus, this case study enables us to compare theories about managing. From a neo-liberal point of view, the common administration of resources of this kind is inefficient, but for one school of the institutional theory, solutions can come “from within”; in other words, from user groups themselves, who can co-operate, once they have defined commitments. Research based on surveys and interviews with private sector administrators leads to the conclusion that user association management is successful, whereas, individual management can lead to squandering.

Description: The content of the paper is focused on determining the influence of an old municipal landfill site on the pollution of soil and groundwater by ammonium. The assessment of the influence was conducted on piezometric recording basis, laboratory tests and site investigation, which gave information on contamination level and direction of pollutants migration. Based on the groundwater monitoring results, several maps of groundwater level changes were created. Moreover, mapping of ammonium distribution and migration paths within Lubna Landfill surroundings was also provided. The monitoring data show improvement of water quality in almost every piezometer after only a few years from when groundwater protection system was installed at the site. It indicates that reduction of ammonium within the vicinity of the landfill is continuously progressing in time. On the basis of the results obtained, the magnitude of variability in pollutant migration and changes in concentration, as well as efficiency of the vertical barrier were assessed.

Description: In this paper we deal with the problem of missing data in environmental cost-benefit analysis. If government pursues the goal of maximizing social welfare, this implies that public funds should be allocated to those uses where they generate the highest net social benefit. This criterion makes it necessary to conduct cost-benefit analyses for public projects. While the assessment of project costs is typically rather straightforward, a comprehensive assessment of the project benefits is more complicated because one has to consider that also people living far away from the project site might benefit from that project. Neglecting these so-called passive use benefits would lead to a systematic undervaluation of environmental projects, thereby reducing their chances of being realized. A comprehensive cost-benefit analysis would, therefore, require benefit assessment studies in all areas where passive use values might occur. Obviously, this would be impossible. In this paper we show how the assessment of the social benefits from environmental projects can be enhanced even with an imperfect database by using benefit transfer techniques. This is also illustrated empirically using an example from Northwest China.

Description: In a previous study, we showed that widespread adoption of water-saving equipment had the potential to reduce CO2 emissions by 1% in Japan. The usage of already diffused equipment was used as an evaluation baseline. This was an evaluation model of developed countries. In order to evaluate the potential benefits of water-saving in developing countries, it is necessary to set the baseline, as cities in developing countries are expected to have the necessary infrastructure in place in the near future. In this paper, the potential for reducing CO2 emissions by water saving in Vietnam was evaluated. Based on the development of water infrastructure, and envisioning a society in which the latest high-efficiency flush toilet bowls and showers installed in Hanoi and Ho Chi Minh City are used in all Vietnamese houses as a near future baseline, we evaluated the potential reduction when a water-saving project is implemented. Under these conditions, an 8.8% reduction in CO2 emissions in Vietnam would be achieved by the widespread adoption of water-saving equipment. Following the recognition of the large environmental contribution potential of water saving, a water-saving project has been planned for implementation in Vietnam in the near future.

Description: Existing flocculation models for cohesive sediments are classified into two groups: population balance equation models (PBE) and floc growth models. An FGM ensures mass conservation in a closed system. However, an FGM determines only the average size of flocs, whereas a PBE has the capability to calculate a size distribution of flocs. A new stochastic approach to model the flocculation process is theoretically developed and incorporated into a deterministic FGM in this study in order to calculate a size distribution of flocs as well as the average size. A log-normal distribution is used to generate random numbers based on previous laboratory experiments. The new stochastic flocculation model is tested with three laboratory experiment results. It was found and validated with measured data that the new stochastic flocculation model has the capability to replicate a size distribution of flocs reasonably well under different sediment and carrier flow conditions. Three more distributions (normal; Pearson type 3; and generalized extreme value distributions) were also tested. From the comparison with results of different distribution functions, it is shown that a stochastic FGM using a log-normal distribution has a comparative advantage in terms of simplicity and accuracy.

Description: The atmospheric chloride mass balance (CMB) method was used to estimate net aquifer recharge in Las Cañadas Caldera, an endorheic summit aquifer area about 2000 m a.s.l. with negligible surface runoff, which hosts the largest freshwater reserve in Tenerife Island, Canary Islands, Spain. The wet hydrological year 2005–2006 was selected to compare yearly atmospheric chloride bulk deposition and average chloride content in recharge water just above the water table, both deduced from periodical sampling. The potential contribution of chloride to groundwater from endogenous HCl gas may invalidate the CMB method. The chloride-to-bromide molar ratio was an efficient tracer used to select recharge water samples having atmospheric origin of chloride. Yearly net aquifer recharge was 631 mm year−1, i.e., 69% of yearly precipitation. This result is in agreement with potential aquifer recharge estimated through an independent lumped-parameter rainfall-runoff model operated by the Insular Water Council of Tenerife. This paper illustrates basic procedures and routines to use the CMB method for aquifer recharge in active volcanic oceanic islands having sparse-data coverage and groundwater receiving contribution of endogenous halides.

Description: In this contribution we analyze the performance of a monthly river discharge forecasting model with a Support Vector Regression (SVR) technique in a European alpine area. We considered as predictors the discharges of the antecedent months, snow-covered area (SCA), and meteorological and climatic variables for 14 catchments in South Tyrol (Northern Italy), as well as the long-term average discharge of the month of prediction, also regarded as a benchmark. Forecasts at a six-month lead time tend to perform no better than the benchmark, with an average 33% relative root mean square error (RMSE%) on test samples. However, at one month lead time, RMSE% was 22%, a non-negligible improvement over the benchmark; moreover, the SVR model reduces the frequency of higher errors associated with anomalous months. Predictions with a lead time of three months show an intermediate performance between those at one and six months lead time. Among the considered predictors, SCA alone reduces RMSE% to 6% and 5% compared to using monthly discharges only, for a lead time equal to one and three months, respectively, whereas meteorological parameters bring only minor improvements. The model also outperformed a simpler linear autoregressive model, and yielded the lowest volume error in forecasting with one month lead time, while at longer lead times the differences compared to the benchmarks are negligible. Our results suggest that although an SVR model may deliver better forecasts than its simpler linear alternatives, long lead-time hydrological forecasting in Alpine catchments remains a challenge. Catchment state variables may play a bigger role than catchment input variables; hence a focus on characterizing seasonal catchment storage—Rather than seasonal weather forecasting—Could be key for improving our predictive capacity.

Description: Understanding the spatio-temporal variation and the potential source of water pollution could greatly improve our knowledge of human impacts on the environment. In this work, data of 11 water quality indices were collected during 2012–2014 at 10 monitoring sites in the mainstream and major tributaries of the Danjiangkou Reservoir Basin, Central China. The fuzzy comprehensive assessment (FCA), the cluster analysis (CA) and the discriminant analysis (DA) were used to assess the water pollution status and analyze its spatio-temporal variation. Ten sites were classified by the high pollution (HP) region and the low pollution (LP) region, while 12 months were divided into the wet season and the dry season. It was found that the HP region was mainly in the small tributaries with small drainage areas and low average annual discharges, and it was also found that most of these rivers went through urban areas with industrial and domestic sewages input into the water body. Principal component analysis/factor analysis (PCA/FA) was applied to reveal potential pollution sources, whereas absolute principal component score-multiple linear regression (APCS-MLR) was used to identify their contributions to each water quality variable. The study area was found as being generally affected by industrial and domestic sewage. Furthermore, the HP region was polluted by chemical industries, and the LP region was influenced by agricultural and livestock sewage.

Description: Adequate infiltration through Permeable Interlocking Concrete Pavements (PICPs) is critical to their hydraulic and stormwater treatment performance. Infiltration is affected by clogging caused by the trapping of fines in the PICP surface, which, over time, reduces treatment performance. Clogging can be reduced by periodic maintenance such as vacuum sweeping and/or pressure washing. Maintenance requirements can be indicated by measuring reduced infiltration rates. This paper compared infiltration results using the standard test (C1781M-14a) with the results of a new stormwater infiltration field test (SWIFT) developed in Australia to evaluate the maintenance requirements of PICPs. A strong correlation (Pearson’s r = −0.714) was found between results using the two methods. This study found that the SWIFT was a reliable method for estimating the degree of clogging of PICPs while successfully overcoming some of the problems with the more technical existing test methodology such as horizontal water leakage (use of sealant), unrealistic pressure heads, speed of test, and portability. The SWIFT test is a simple, fast and inexpensive way for asset managers and local government employees to quickly assess the maintenance requirements of PICP installations in the field.

Description: Water deficit in semi-arid regions limits the future of the livestock sector. Also, its high price represents a percentage of the total cost of forage production. Non-conventional water resources applied by subsurface drip irrigation (SDI), in which the safe use lies in the management and not on the level of water treatment, would enhance the ruminant production sustainability. To obtain the optimal benefit, the transformation of water per kilogram of dry matter produced must have a high grade of effectiveness. Under this premise, a maralfalfa crop (Penissetum sp, hybridum) has been established with an SDI system and reclaimed water. Forage yield is analyzed with respect to a 40% irrigation reduction. This study shows that, with the use of these good irrigation management practices, it is possible to harvest an annual production of 90 to 72 t·ha−1 in the warmer regions of the Canary Islands. This implies water consumption between 13,200 and 8100 m3·ha−1. A water consumption of 21,000 m3·ha−1 per year for the same production, at a ratio of 230 L·t−1, can be estimated for the rest of the Canary Islands coastal regions. The use of the water management described in this paper can be profitable in the Canary Islands for fodder production.

Description: The chloride mass balance method was used to estimate the average diffuse groundwater recharge on northeastern Gran Canaria (Canary Islands), where the largest recharge to the volcanic island aquifer occurs. Rainwater was sampled monthly in ten rainwater collectors to determine the bulk deposition rate of chloride for the 2008–2014 period. Average chloride deposition decreases inwardly from more than 10 g·m−2·year−1 to about 4 g·m−2·year−1. The application of the chloride mass balance method resulted in an estimated average recharge of about 28 hm3/year or 92 mm/year (24% of precipitation) in the study area after subtracting chloride loss with surface runoff. The average storm runoff was estimated to be 12 hm3/year (9% of precipitation) for the 1980–2014 period. Runoff was sampled during scarce rainy periods, which produce surface water flow. Average recharge varies from less than a few mm/year near the coast up to 270 mm/year in the highlands (about 33% of average rainfall), with a close-to-linear increase inwardly of about 18 mm·year−1·km−1. Recharge rate uncertainty corresponds to an estimated CV of 0.3–0.4 because of the short data series available.

Description: Rain gauge and satellite-retrieved data have been widely used in basin-scale hydrological applications. While rain gauges provide accurate measurements that are generally unevenly distributed in space, satellites offer spatially regular observations and common error prone retrieval. Comparative evaluation of gauge-based and satellite-based data is necessary in hydrological studies, as precipitation is the most important input in basin-scale water balance. This study uses quality-controlled rain gauge data and prevailing satellite products (Tropical Rainfall Measuring Mission (TRMM) 3B43, 3B42 and 3B42RT) to examine the consistency and discrepancies between them at different scales. Rain gauges and TRMM products were available in the Poyang Lake Basin, China, from 1998 to 2007 (3B42RT: 2000–2007). Our results show that the performance of TRMM products generally increases with increasing spatial scale. At both the monthly and annual scales, the accuracy is highest for TRMM 3B43, with 3B42 second and 3B42RT third. TRMM products generally overestimate precipitation because of a high frequency and degree of overestimation in light and moderate rain cases. At the daily scale, the accuracy is relatively low between TRMM 3B42 and 3B42RT. Meanwhile, the performances of TRMM 3B42 and 3B42RT are highly variable in different seasons. At both the basin and pixel scales, TRMM 3B43 and 3B42 exhibit significant discrepancies from July to September, performing worst in September. For TRMM 3B42RT, all statistical indices fluctuate and are low throughout the year, performing worst in July at the pixel scale and January at the basin scale. Furthermore, the spatial distributions of the statistical indices of TRMM 3B43 and 3B42 performed well, while TRMM 3B42RT displayed a poor performance.

Description: Flood is a frequent natural hazard that has significant financial consequences for Australia. In Australia, physical losses caused by floods are commonly estimated by stage-damage functions. These methods usually consider only the depth of the water and the type of buildings at risk. However, flood damage is a complicated process, and it is dependent on a variety of factors which are rarely taken into account. This study explores the interaction, importance, and influence of water depth, flow velocity, water contamination, precautionary measures, emergency measures, flood experience, floor area, building value, building quality, and socioeconomic status. The study uses tree-based models (regression trees and bagging decision trees) and a dataset collected from 2012 to 2013 flood events in Queensland, which includes information on structural damages, impact parameters, and resistance variables. The tree-based approaches show water depth, floor area, precautionary measures, building value, and building quality to be important damage-influencing parameters. Furthermore, the performance of the tree-based models is validated and contrasted with the outcomes of a multi-parameter loss function (FLFArs) from Australia. The tree-based models are shown to be more accurate than the stage-damage function. Consequently, considering more parameters and taking advantage of tree-based models is recommended. The outcome is important for improving established Australian flood loss models and assisting decision-makers and insurance companies dealing with flood risk assessment.

Description: This paper recounts the environmental history of a main waterway in Northern Israel—the Kishon, and deploys this history to examine the evolution of Israel water policy as it struggled to bridge the growing gap between its ambitions of development and the realities of its limited water supply. The first part of the paper describes the decay of the Kishon since the early 1950s, and the multiple scientific, political and legal attempts to alleviate its misfortunes, and discusses the reasons for their failings. Some of these reasons were administrative by nature, but the paper suggests a deeper reason, rooted in the ideological core of the infant state that was overwhelmingly concerned with the development of its infrastructure, and invited the pioneering Israeli society to consider the demise of the Kishon as a necessary sacrifice for progress. The second part of the paper describes the late-20th century developments that allowed for the recovery of the ailing river. Changing social mores, the growing importance of environmental politics, the advance of Israel’s water technologies, and an environmental scandal that endowed the rehabilitation of the Kishon with a new political and moral meaning, have all contributed to the rehabilitation of the river. Once a testament for the sacrifices involved in a struggle to create a viable state, the Kishon has become a theater for a confident society that has triumphed in its struggle against nature.

Description: A detention reservoir is one of the most effective engineered solutions for flood damage mitigation in urban areas. Detention facilities are constructed to temporarily store storm water and then slowly drain when the peak period has passed. This delayed drainage may coincide with upstream floods and aggravate the flood risk downstream. Optimal operation and design are needed to improve the performance of detention reservoirs for flood reduction. This study couples hydrologic simulation software (EPA-SWMM) with an evolutional optimizer (extraordinary particle swarm optimization, EPSO) to minimize flood damage downstream while considering the inundation risk at the detention reservoir. The optimum design and operation are applied to an urban case study in Seoul, Korea, for historical severe flooding events and designed rainfall scenarios. The optimal facilities outperform the present facilities in terms of flood damage reduction both downstream and in the detention reservoir area. Specifically, the peak water level at the detention pond under optimal conditions is significantly smaller than that of the current conditions. The comparison of the total flooded volume in the whole watershed shows a dramatic reduction of 79% in a severe flooding event in 2010 and around 20% in 2011 and in 180 min designed rainfall scenarios.

Description: The study of the Rio Grande/Bravo (RGB) Basin water allocation demonstrates how the United States (U.S.) and Mexico have consolidated a transboundary framework based on water sharing. However, the water supply no longer meets the ever-increasing demand for water or the expectations of different stakeholders. This paper explores opportunities for an enhanced management regime that will address past problems and better examine how to balance demands for a precious resource and environmental needs. Based on an overview of the RGB Basin context and the water allocation framework, as well as a discussion on stakeholders’ ability to achieve solutions, this paper explores three key questions: (1) Does the current binational water allocation framework meet current and future human and environmental needs? (2) How can the U.S.-Mexico water allocation framework be adapted to balance social and environmental water demands so it can support and preserve the RGB Basin ecosystem? (3) What are the main opportunities to be explored for expanding the U.S.-Mexico water resources allocation framework? The U.S.-Mexico water resources framework is subject to broad interpretation and may be adapted to the circumstances taking the fullest advantage of its flexibility. Policy recommendations highlight the existing flexibility of the binational framework, the potential to move forward with an ad hoc institutional arrangement, and the creation of political will to achieve change through stakeholders recommendations.

Description: Stormwater runoff quality was measured with online turbidity sensors at four common types of small urban subcatchments: (i) a flat roof; (ii) a parking lot; (iii) a residential catchment; and (iv) a high-traffic street. Samples were taken to estimate site-specific correlations between total suspended solids (TSS) and turbidity. Continuous TSS time series were derived from online turbidity measurements and were used to estimate event loads and event mean concentrations. Rainfall runoff event characteristics were subjected to correlation analysis to TSS loads. Significant correlations were found for rainfall intensities at sites with high imperviousness and decrease with increasing catchment size. Antecedent dry weather periods are only correlated at the parking lot site. Intra-event TSS load distributions were studied with M (V)-curves. M (V)-curves are grouped at runoff quantiles and statistically described with boxplots. All sites show, in general, a more pronounced first-flush effect. While wash-off of the flat roof tends to be source-limited, the parking lot and high-traffic street sites show a more transport-limited behavior. Wash-off process of the residential catchment appears to be influenced by a composition of different subcatchments.

Description: Water is used in dairy farming for producing feed, watering the animals, and cleaning and disinfecting barns and equipment. The objective of this study was to investigate the drinking and cleaning water use in a dairy cow barn. The water use was measured on a well-managed commercial dairy farm in North-East Germany. Thirty-eight water meters were installed in a barn with 176 cows and two milking systems (an automatic milking system and a herringbone parlour). Their counts were logged hourly over 806 days. On average, the cows in the automatic milking system used 91.1 (SD 14.3) L drinking water per cow per day, while those in the herringbone parlour used 54.4 (SD 5.3) L per cow per day. The cows drink most of the water during the hours of (natural and artificial) light in the barn. Previously published regression functions of drinking water intake of the cows were reviewed and a new regression function based on the ambient temperature and the milk yield was developed (drinking water intake (L per cow per day) = −27.937 + 0.49 × mean temperature + 3.15 × milk yield (R2 = 0.67)). The cleaning water demand had a mean of 28.6 (SD 14.8) L per cow per day in the automatic milking system, and a mean of 33.8 (SD 14.1) L per cow per day in the herringbone parlour. These findings show that the total technical water use in the barn makes only a minor contribution to water use in dairy farming compared with the water use for feed production.

Description: Waves induced by ship movement might be harmful for the habitat in the littoral zone of rivers due to the temporally increasing bed shear stress, the high-energy breaking waves and the consequently related detachment of benthic animals. In order to understand the complex hydrodynamic phenomena resulting from littoral waves, we present the testing of a novel methodology that incorporates field observations and numerical tools. The study is performed at a section of the Danube River in Hungary and analyzes the influence of different ship types. The field methods consist of parallel acoustic measurements (using Acoustic Doppler Velocimetry (ADV)) conducted at the riverbed and Large Scale Particle Image Velocimetry (LSPIV) of the water surface. ADV measurements provided near-bed flow velocities based on which the wave induced currents and local bed shear stress could be estimated. The LSPIV was able to quantify the dynamics of the breaking waves along the bank. Furthermore, computational fluid dynamics (CFD) modeling was successfully applied to simulate the propagation and the breaking of littoral waves. The used techniques complement each other well and their joint application provides an adequate tool to support the improvement of riverine habitats.

Description: The classical working principle of aquaponics is to provide nutrient-rich aquacultural water to a hydroponic plant culture unit, which in turn depurates the water that is returned to the aquaculture tanks. A known drawback is that a compromise away from optimal growing conditions for plants and fish must be achieved to produce both crops and fish in the same environmental conditions. The objective of this study was to develop a theoretical concept of a decoupled aquaponic system (DAPS), and predict water, nutrient (N and P), fish, sludge, and plant levels. This has been approached by developing a dynamic aquaponic system model, using inputs from data found in literature covering the fields of aquaculture, hydroponics, and sludge treatment. The outputs from the model showed the dependency of aquacultural water quality on the hydroponic evapotranspiration rate. This result can be explained by the fact that DAPS is based on one-way flows. These one-way flows results in accumulations of remineralized nutrients in the hydroponic component ensuring optimal conditions for the plants. The study also suggests to size the cultivation area based on P availability in the hydroponic component as P is an exhaustible resource and has been identified one of the main limiting factors for plant growth.

Description: The water level of Dongting Lake has changed because of the combined impact of climatic change and anthropogenic activities. A study of the long-term statistical properties of water level variations at Chenglingji station will help with the management of water resources in Dongting Lake. In this case, 54 years of water level data for Dongting Lake were analyzed with the non-parametric Mann–Kendall trend test, Sen’s slope test, and the Pettitt test. The results showed the following: (1) Trends in annual maximum lake water level (WLM), annual mean lake water level (WL), and annual minimum lake water level (WLm) increased from 1961 to 2014; however, the three variables showed different trends from 1981 to 2014; (2) The annual change trends in Dongting Lake between 1961–2014 and 1981–2014 were found to be from approximately 0.90 cm/year to −2.27 cm/year, 1.65 cm/year to −0.79 cm/year, and 4.58 cm/year to 2.56 cm/year for WLM, WL, and WLm, respectively; (3) A greater degree of increase in water level during the dry season (November–April) was found from 2003 to 2014 than from 1981 to 2002, but a smaller degree of increase, even to the point of decreasing, was found during the wet season (May–October); (4) The measured discharge data and numerical modeling results showed the operation of Three Gorge Reservoir (TGR) pushed to influence partly the recent inter-annual variation of water level in Dongting Lake region, especially in the flood and dry seasons. The analysis indicated that the water level of Dongting Lake has changed in the long term with decreasing of range between WLM and WLm, and may decrease the probability of future drought and flood events. These results can provide useful information for the management of Dongting Lake.

Description: The voluntary Water Efficiency Labelling Scheme (WELS) on showers for bathing in Hong Kong is a water conservation initiative of the Hong Kong Special Administrative Region (HKSAR) Government. As shower water consumption has been identified as a potential area for carbon emissions reductions, this study examines, from a five-month measurement survey of the showering practices of 37 local residents, a range of showerheads with resistance factors k = 0.54–4.05 kPa·min2·L−2 with showering attributes including hot shower temperature, temperature difference between hot and cold water supply, flow rate and water consumption and shower duration. A Monte Carlo model is proposed for evaluating the water consumption and carbon-reducing impacts of WELS on showers for bathing at confidence intervals with input parameters determined from the measurement survey. The simulation results indicate that full implementation of WELS rated showerheads with k ≥ 4.02 can reduce water consumption by 37%, energy use by 25% and carbon dioxide (CO2) emissions by 26%. This study is also a useful source of reference for policymakers and practitioners to evaluate the impacts of water efficient showerheads on water consumption, energy use, and CO2 emissions.

Description: The authors wish to make the following corrections to this paper [1]: The author name “Bernard A. Engle” should be “Bernard A. Engel”[...]

Description: Pluvial floods have caused severe damage to urban areas in recent years. With a projected increase in extreme precipitation as well as an ongoing urbanization, pluvial flood damage is expected to increase in the future. Therefore, further insights, especially on the adverse consequences of pluvial floods and their mitigation, are needed. To gain more knowledge, empirical damage data from three different pluvial flood events in Germany were collected through computer-aided telephone interviews. Pluvial flood awareness as well as flood experience were found to be low before the respective flood events. The level of private precaution increased considerably after all events, but is mainly focused on measures that are easy to implement. Lower inundation depths, smaller potential losses as compared with fluvial floods, as well as the fact that pluvial flooding may occur everywhere, are expected to cause a shift in damage mitigation from precaution to emergency response. However, an effective implementation of emergency measures was constrained by a low dissemination of early warnings in the study areas. Further improvements of early warning systems including dissemination as well as a rise in pluvial flood preparedness are important to reduce future pluvial flood damage.

Description: Various maize irrigation treatments including full and deficit irrigation were used to calibrate and validate the soil water balance and irrigation scheduling model SIMDualKc at Paysandú, western Uruguay. The model adopts the dual crop coefficient approach to partition actual evapotranspiration (ETc act) into actual transpiration (Tc act) and soil evaporation (Es). Low errors of estimation were obtained for simulating soil water content (Root mean square errors (RMSE) ≤ 0.014 cm3·cm−3 with calibrated parameters, and RMSE ≤ 0.023 cm3·cm−3 with default parameters). The ratio Es/Tc act ranged from 26% to 33% and Es/ETc act varied from 20% to 25%, with higher values when the crop was stressed offering less soil coverage. Due to rainfall regime, runoff and deep percolation were quite large. The Stewarts phasic model was tested and used to predict maize yield from Tc act with acceptable errors, in the range of those reported in literature. Water productivity values were high, ranging 1.39 to 2.17 kg·m−3 and 1.75 to 2.55 kg·m−3 when considering total water use and crop ET, respectively. Using a 22-year climatic data series, rainfed maize was assessed with poor results for nearly 40% of the years. Differently, alternative supplemental irrigation schedules assessed for the dry and very dry years have shown good results, particularly for mild deficit irrigation. Overall, results show appropriateness for using SIMDualKc to support the irrigation practice.

Description: The aquaculture sector has been increasing its share in the total fish production in the world. Numerous studies have been published about aquaculture, introducing a variety of techniques and methods that have been applied or could be applied in aquaculture production systems. The purpose of this study is to present a systemic overview of the functions of aquaculture production systems. Each function of an aquaculture system is applied to carry out a certain purpose. The results are divided into three sets of functions: input, treatment, and output. Input functions deal with what happens before the rearing area, treatment functions are about what happens inside the rearing area, and output functions is what comes out of the system. In this study, five input functions, ten treatment functions, and five output functions are indentified. For each function the controlling parameters or indicators were identified and then a list of possible methods or technological solutions in order to carry out the function was compiled. The results are presented in a system map that aggregates all functions used in different types of aquaculture systems along with their methods of solution. This is the first of four articles that together generate taxonomy of both means and ends in aquaculture. The aim is to identify both the technical solutions (means) that solve different functions (ends) and the corresponding functions. This article is about the functions.

Description: Urban stormwater with large impervious (paved) areas often produces runoff with a variety of contaminants. Although southern California is among the most urbanized coastal areas in the United States, the effect of rainfall variations on washoff efficiency of contaminants from pervious and impervious surfaces is largely unknown. The goal of this study was to investigate the effect of varying rainfall intensities and duration on runoff composition from highly impervious parking lots. In order to control the tremendous natural variability in precipitation of the arid climate in southern California, rainfall simulators were used to generate and quantify pollutant washoff at changing intensities and durations. Washoff of suspended solids, total and dissolved trace metals, and polycyclic aromatic hydrocarbons was strongly inversely correlated with rainfall duration. Rainfall intensity only affected washoff at the smallest measured duration; higher intensities produced decreased concentrations. The effect of rainfall duration was a reflection of the first flush observed in pollutographs for every duration and intensity sampled. Peak concentrations, up to an order of magnitude higher than concentrations later in the event, occurred during the first 10 min after the onset of rainfall. Longer simulated storms effectively diluted the first flush.

Description: A comparative study of two coagulants, aluminum sulfate (Alum) and aluminum chlorohydrate (ACH), used in parallel in a full scale water treatment plant (WTP) in Ohio from October 2009 to December 2012, was conducted to determine disinfection by-product (DBP) formation potential removal based on both dissolved organic matter (DOM) and fluorescence-derived metrics. Water quality parameters and fluorescence intensity of water samples collected before and after coagulation were measured three times per week and fluorescence matrices were analyzed using parallel factor (PARAFAC) analysis, while DBP formation potential was measured in a weekly basis in pre- and post-coagulation water samples. This study revealed that Alum consistently removed more trihalomethane (THM) formation potential per mg/L of dissolved organic carbon (DOC) than ACH. ACH treated waters averaged approximately 33% more THM formation potential when normalized to DOC. Similarly, haloacetic acid (HAA) formation potential averaged 10% higher in ACH treated waters. From the fluorescence analysis, PARAFAC components C1 and C2 (humic-like fluorophores groups) removal were 23% and 16% higher, respectively, with Alum when compared to ACH. Monte Carlo simulations, based on neural network models developed from the field data, were performed to compare DBP formation across a wide range of conditions. At similar pH, the model results showed that ACH coagulated water had 13% and 20% higher THM and HAA formation potential, respectively, when compared with Alum. The observations from this study reveal that a coagulant’s preferential removal of DBP precursors has an impact on DBP formation despite similar DOC removal.

Description: Ecological monitoring and assessment is fundamental for effective management of ecosystems. As an introduction to this Special Issue, this editorial provides an overview of “Ecological Monitoring, Assessment, and Management in Freshwater Systems”. This issue contains a review article on monitoring surface waters, and research papers on data management, biological assessment of aquatic ecosystems, water quality assessment, effects of land use on aquatic ecosystems, etc. The papers in this issue contribute to the existing scientific knowledge of freshwater ecology. They also contribute to the development of more reliable biological monitoring and assessment methods for sustainable freshwater ecosystems and ecologically acceptable decision-making policies, and establishment of practices for effective ecosystem management and conservation.

Description: Climate warming threatens biodiversity at global, regional and local levels by causing irreversible changes to species populations and biological communities. The Himalayan region is highly vulnerable to climate warming. This calls for efficient environmental management strategies because biodiversity monitoring is costly, particularly for the developing countries of the Himalaya. Species distribution modeling (SDM) represents a tool that can be used to identify vulnerable areas where biodiversity monitoring and conservation are required most urgently and can be prioritized. Here, we investigated the potential present-day community compositions of river invertebrates in the central and eastern Himalayas and predicted changes in community compositions in future decades using SDMs. We then quantified the climate-induced range shifts of benthic invertebrates along the elevational gradient and tested whether the predicted community shift is fast enough to fully compensate for the projected climate warming. Our model predicts future increases in benthic invertebrate taxonomic richness. Further, projected community shifts are characterized by the movement of warm-dwellers to higher elevations and losses in cold-dwellers. The predicted model shows that benthic invertebrate communities would not be able to compensate climate warming through uphill migration and thus would accumulate climatic debts. Our findings suggest that the ongoing warming effect would cause continued elevational range shifts of mountain river communities.

Description: Nitrate contamination in rivers has raised widespread concern in the world, particularly in arid/semi-arid river basins lacking qualified water. Understanding the nitrate pollution levels and sources is critical to control the nitrogen input and promote a more sustainable water management in those basins. Water samples were collected from a typical semi-arid river basin, the Weihe River watershed, China, in October 2014. Hydrochemical assessment and nitrogen isotopic measurement were used to determine the level of nitrogen compounds and identify the sources of nitrate contamination. Approximately 32.4% of the water samples exceeded the World Health Organization (WHO) drinking water standard for NO3−-N. Nitrate pollution in the main stream of the Weihe River was obviously much more serious than in the tributaries. The δ15N-NO3− of water samples ranged from +8.3‰ to +27.0‰. No significant effect of denitrification on the shift in nitrogen isotopic values in surface water was observed by high dissolved oxygen (DO) values and linear relationship diagram between NO3−-N and δ15N-NO3−, except in the Weihe River in Huayin County and Shitou River. Analyses of hydrochemistry and isotopic compositions indicate that domestic sewage and agricultural activities are the main sources of nitrate in the river.

Description: With the high demand for freshwater and its vital role in sustaining multiple ecosystem services, it is important to quantify and evaluate freshwater provisioning for various services (e.g., drinking, fisheries, recreation). Research on ecosystem services has increased recently, though relatively fewer studies apply a data driven approach to quantify freshwater provisioning for different ecosystem services. In this study, freshwater provisioning was quantified annually from 1995 to 2013 for 13 watersheds in the Upper Mississippi River Basin (UMRB). Results showed that the annual freshwater provision indices for all watersheds were less than one indicating that freshwater provisioning is diminished in the UMRB. The concentrations of sediment and nutrients (total nitrogen, and total phosphorus) are the most sensitive factors that impact freshwater provisioning in the UMRB. A significant linear relationship was observed between precipitation and freshwater provisioning index. During wet periods freshwater provisioning generally decreased in the study watersheds, primarily because of relatively high concentrations and loads of sediment and nutrients delivered from nonpoint sources. Results from this study may provide an insight, as well as an example of a data-driven approach to enhance freshwater provisioning for different ecosystem services and to develop a sustainable and integrated watershed management approach for the UMRB.

Description: The Long Term Hydrologic Impact Assessment (L-THIA) model was previously improved by incorporating direct runoff lag time and baseflow. However, the improved model, called the L-THIA asymptotic curve number (ACN) model cannot simulate pollutant loads from a watershed or instream water quality. In this study, a module for calculating pollutant loads from fields and through stream networks was developed, and the L-THIA ACN model was combined with the QUAL2E model (The enhanced stream water quality model) to predict instream water quality at a watershed scale. The new model (L-THIA ACN-WQ) was applied to two watersheds within the Korean total maximum daily loads management system. To evaluate the model, simulated results of total nitrogen (TN) and total phosphorus (TP) were compared with observed water quality data collected at eight-day intervals. Between simulated and observed data for TN pollutant loads in Dalcheon A watershed, the R2 and Nash–Sutcliffe efficiency (NSE) were 0.81 and 0.79, respectively, and those for TP were 0.79 and 0.78, respectively. In the Pyungchang A watershed, the R2 and NSE were 0.66 and 0.64, respectively, for TN and both statistics were 0.66 for TP, indicating that model performed satisfactorily for both watersheds. Thus, the L-THIA ACN-WQ model can accurately simulate streamflow, instream pollutant loads, and water quality.

Description: Metals such as antimony, cadmium, chromium, copper, lead, nickel, and zinc can be highly relevant pollutants in stormwater runoff from traffic areas because of their occurrence, toxicity, and non-degradability. Long-term measurements of their concentrations, the corresponding water volumes, the catchment areas, and the traffic volumes can be used to calculate specific emission loads and annual runoff loads that are necessary for mass balances. In the literature, the annual runoff loads are often specified by a distinct catchment area (e.g., g/ha). These loads were summarized and discussed in this paper for all seven metals and three types of traffic areas (highways, parking lots, and roads; 45 sites). For example, the calculated median annual runoff loads of all sites are 355 g/ha for copper, 110 g/ha for lead (only data of the 21st century), and 1960 g/ha for zinc. In addition, historical trends, annual variations, and site-specific factors were evaluated for the runoff loads. For Germany, mass balances of traffic related emissions and annual heavy metal runoff loads from highways and total traffic areas were calculated. The influences on the mass fluxes of the heavy metal emissions and the runoff pollution were discussed. However, a statistical analysis of the annual traffic related metal fluxes, in particular for different traffic area categories and land uses, is currently not possible because of a lack of monitoring data.

Description: Determining the spatiotemporal water quality patterns and their corresponding driving factors is crucial for lake water quality managements. This study analyzed hydrological data and concentrations of 11 water quality parameters, including total nitrogen, total phosphorus, ammonia nitrogen and chlorophyll–a (Chl–a), for water samples collected from 15 sampling sites between 2009 and 2014. The water quality of sites in the northern Poyang Lake–Yangtze River waterway was influenced by different environmental parameters compared to sites in central lake, especially for Chl–a concentration. All pollutant parameters were significantly higher in the river phase (water level 〈14 m) than in the lake phase (water level >14 m) (p 〈 0.05). These results were confirmed via principal component analysis, which identified three principal components that explained over 79% of the dataset variance. Among all the parameters related to climatic factors, eutrophication and organic pollution were the most important contributors in water quality. Dilution was the controlling factor that drove the seasonal variability in the water quality of the Poyang Lake, China. This work further indicated that regulating pollutant effluents in tributaries and water level within the lake could improve the water quality in Poyang Lake, which may give some impetus for water quality management.

Description: Water is an essential element for life, and development would not be possible without its availability. This study identified the main water consumers and their likely impact on water lake level for the case of Issyk-Kul Lake Basin, Kyrgyzstan. Data on precipitation, lake level, irrigation, household and industrial water consumption from 1980 to 2014 were provided by the Department of Water Resources and Irrigation, Ministry of Agriculture and Land Reclamation of the Kyrgyz Republic. The input data was analyzed with OriginPro 8.5 for Statistical Analysis. The results indicated a decreasing irrigation water consumption from 2029.42 to 461.76 million·m3 in 1980 and 2014, respectively. Likewise, households consumed 27.02 million·m3 in 1980 falling to 16.55 million·m3 in 2014, similar to the manufacture’s water consumption. However, it was noted that agriculture is a high water consumer, whose water demand for irrigation rises from April to August, the period during which the precipitation also increases. Nevertheless, manufactures and household water consumption do not have timed limits of use like in agriculture, which in turn affects the lake water level. Therefore, as the rainfall increases by April to August, we suggest to harvest and only use the rainfall water during its abundance period. This would help in restoring the lake’s water level during the time of rainwater uses, and leads to water consumption balance, flood management and lake biodiversity conservation as well.

Description: This paper presents the hydrological analysis and grain size characteristics of fluvial sediments in a river basin and their combination to characterize a flood event. The overall objective of the research is the development of a practical methodology based on experimental surveys to reconstruct the hydraulic history of ungauged river reaches on the basis of the modifications detected on the riverbed during the dry season. The grain size analysis of fluvial deposits usually requires great technical and economical efforts and traditional sieving based on physical sampling is not appropriate to adequately represent the spatial distribution of sediments in a wide area of a riverbed with a reasonable number of samples. The use of photographic sampling techniques, on the other hand, allows for the quick and effective determination of the grain size distribution, through the use of a digital camera and specific graphical algorithms in large river stretches. A photographic sampling is employed to characterize the riverbed in a 3 km ungauged reach of the Tescio River, a tributary of the Chiascio River, located in central Italy, representative of many rivers in the same geographical area. To this end, the particle size distribution is reconstructed through the analysis of digital pictures of the sediments taken on the riverbed in dry conditions. The sampling has been performed after a flood event of known duration, which allows for the identification of the removal of the armor in one section along the river reach under investigation. The volume and composition of the eroded sediments made it possible to calculate the average flow rate associated with the flood event which caused the erosion, by means of the sediment transport laws and the hydrological analysis of the river basin. A hydraulic analysis of the river stretch under investigation was employed to verify the validity of the proposed procedure.

Description: Several inversion modeling-based approaches have been developed/used to extract soil hydraulic properties (α, n, θres, θsat, Ksat) from remotely sensed (RS) soil moisture footprints. Hydrological models with shallow ground water (SGW) table depths in soils simulate daily root zone soil moisture dynamics based on the extracted soil parameters. The presence of SGW table depths in soils significantly influences model performances; however, SGW table depths are usually unknown in the field, thus, unknown SGW table depths might cause uncertainties in the model outputs. In order to overcome these drawbacks, we developed a dynamic ground water (DGW) data assimilation approach that can consider SGW table depths across time for quantifying effective soil hydraulic properties in the unsaturated zone. In order to verify the DGW data assimilation scheme, numerical experiments comprising synthetic and field validation experiments were conducted. For the numerical studies, the Little Washita (LW) watershed in Oklahoma and Olney (OLN)/Bondville (BOND) sites in Illinois were selected as different hydroclimatic regions. For the synthetic conditions, we tested the DGW scheme using various soil textures and vegetation covers with fixed and dynamically changing SGW table depths across time in homogeneous and heterogeneous (layered) soil columns. The DGW-based soil parameters matched the observations under various synthetic conditions better than those that only consider fixed ground water (FGW) table depths in time. For the field validations, our proposed data assimilation scheme performed well in predicting the soil hydraulic properties and SGW table depths at the point, airborne sensing, and satellite scales, even though uncertainties exist. These findings support the robustness of our proposed DGW approach in application to regional fields. Thus, the DGW scheme could improve the availability and applicability of pixel-scale soil moisture footprints based on satellite platforms.

Description: Understanding the changes in water consumption structure in order to take measures for demand control is very important for sustainable water resources management. In this study, using the Southern China area of Nanjing as an example, we employed the information entropy method to analyze the water consumption structure, as well as the grey incidence analysis to analyze synthetic incidence degree of the factors associated with agricultural, industrial, domestic, and ecological water consumption. The results show that the degree of balance among water consumption sectors has increased from 0.755 to 0.825 between 1993 and 2014. Gradual decrease of the relative proportion of a single water user structure in a water consumption system has made the utilization of water resources in Nanjing rational and diversified. The study identifies three stages of transformation of water structure in Nanjing, namely, a growth period from 1993 to 2002, an adjustment period from 2003 to 2010, and another growth period from 2011 to 2014. The synthetic incidence degree analysis indicates that adjustments of the agricultural and industrial water consumption as well as water saving measures are the main factors that affected water consumption structure in Nanjing. It is expected that the results obtained from this study will provide references to optimize the utilization of urban water resources.

Description: Regions of scarce fresh water resources, such as the Middle East and North Africa, are facing great challenges already today, and even more in the future, due to climatic and socioeconomic changes. The Middle Drâa valley in Morocco is one of many semi-arid to arid mountainous areas struggling with increasing water scarcity threatening self-sufficient husbandry. In order to maintain people’s livelihoods water management needs to be adapted. The Water Evaluation And Planning System (WEAP) software has been widely used to examine complex water systems in the water resource planning sector all around the world and proved to be a helpful asset to show the various interactions of water supply and demand. This paper presents the application of WEAP on the Middle Draâ valley’s water demand and supply, including several socioeconomic and land use scenarios under one basic climate change scenario. The climate scenario shows a significant decrease in available water resources up to 2029 while all socioeconomic scenarios show an increase in water demand. In years of droughts groundwater is used for irrigation, leading to increasingly depleted aquifers. The aquifers are recharged by percolation losses from irrigation and by river bed infiltration the latter of which is stronger in the northern oases than in the southern oases due to water withdrawal rules. A drastic reduction of irrigated agricultural area is the only solution to guarantee sustainable water use.

Description: This work develops a rule curve-based conjunctive use management model for optimizing the operating rules for a lake–groundwater system with off-stream storage lakes. The proposed procedure is a simulation-optimization approach that embeds an Artificial Neural Network (ANN) instead of a groundwater numerical model into a genetic algorithm (GA). The direct physical exchange between lake water with groundwater is simulated using the ANN model, which is a reduced version of a full numerical model, MODFLOW with an LAK3 module. By applying the ANN model, the proposed procedure can reduce the computational burden that is induced by the nonlinear exchange. An operating rule-based optimal conjunctive use management model for the Gaopin Artificial lakes system in Taiwan was thus developed using the proposed framework. A set of optimal solutions involves rule curves and a discount ratio. Simulation results demonstrate that the embedded ANN model can accurately simulate the nonlinear exchange of a lake with groundwater. The embedded ANN model is less computationally complex than the numerical model. This work demonstrates a methodology for reducing the computational burden of the optimal conjunctive use management model that is associated with an internal nonlinear system by using the ANN reduced model. Specifically, the concept of, and results obtained using the developed operating rule-based model incorporating five artificial lakes and considering the nonlinear exchange of those lakes with the groundwater system provides a valuable practical reference for solving related conjunctive use problems.

Description: Small aquatic ecosystems of the boreal zone are known to be most sensitive indicators of on-going environmental change as well as local anthropogenic pressure, while being highly vulnerable to external impacts. Compared to rather detailed knowledge of the evolution of large and small lakes in Scandinavia and Canada, and large lakes in Eurasia, highly abundant small boreal lakes of northwest Russia have received very little attention, although they may become important centers of attraction of growing rural population in the near future. Here we present the results of a multidisciplinary, multi-annual study of a small boreal humic lake of NW Russia. A shallow (3 m) and a deep (16 m) site of this lake were regularly sampled for a range of chemical and biological parameters. Average multi-daily, summer-time values of the epilimnion (upper oxygenated) layer of the lake provided indications of possible trends in temperature, nutrients, and bacterio-plankton concentration that revealed the local pollution impact in the shallow zone and overall environmental trend in the deep sampling point of the lake. Organic phosphorus, nitrate, and lead were found to be most efficient tracers of local anthropogenic pollution, especially visible in the surface layer of the shallow site of the lake. Cycling of trace elements between the epilimnion and hypolimnion is tightly linked to dissolved organic matter speciation and size fractionation due to the dominance of organic and organo-ferric colloids. The capacity of lake self-purification depends on the ratio of primary productivity to mineralization of organic matter. This ratio remained >1 both during winter and summer periods, which suggests a high potential of lake recovery from the input of allochthonous dissolved organic matter and local anthropogenic pollution.

Description: The effect of fine-scale topographic variability on model estimates of ecohydrologic responses to climate variability in California’s Sierra Nevada watersheds has not been adequately quantified and may be important for supporting reliable climate-impact assessments. This study tested the effect of digital elevation model (DEM) resolution on model accuracy and estimates of the sensitivity of ecohydrologic responses to inter-annual climate variability. The Regional Hydro-Ecologic Simulation System (RHESSys) was applied to eight headwater, high-elevation watersheds located in the Kings River drainage basin. Each watershed was calibrated with measured snow depth (or snow water equivalent) and daily streamflow. Modeled streamflow estimates were sensitive to DEM resolution, even with resolution-specific calibration of soil drainage parameters. For model resolutions coarser than 10 m, the accuracy of streamflow estimates largely decreased. Reduced model accuracy was related to the reduction in spatial variance of a topographic wetness index with coarser DEM resolutions. This study also found that among the long-term average ecohydrologic estimates, summer flow estimates were the most sensitive to DEM resolution, and coarser resolution models overestimated the climatic sensitivity for evapotranspiration and net primary productivity. Therefore, accounting for fine-scale topographic variability in ecohydrologic modeling may be necessary for reliably assessing climate change effects on lower-order Sierra Nevada watersheds (≤2.3 km2).

Description: The current water scarcity situation in South Africa is a threat to sustainable development. The present paper has assessed the water footprint of milk produced and processed in South Africa using the procedures outlined in the water footprint assessment manual. The results show that 1352 m3 of water is required to produce one tonne of milk with 4% fat and 3.3% protein in South Africa. The water used in producing feed for lactating cows alone accounts for 86.35% of the total water footprint of milk. The water footprint of feed ration for lactating cows is about 85% higher than that of non-lactating cows. Green water footprint accounts for more than 86% of the total water footprint of feed ration for lactating cows. Green and blue water footprints are the highest contributors to the total water footprint milk production in South Africa. Water used for feed production for both lactating and non-lactating cows accounts for about 99% of the total water footprint of milk production in South Africa. Particular attention should be given to feed crops with low water footprints and high contribution to dry matter to provide balanced ration with low water footprint. Water users, managers and livestock producers should pay attention to green and blue water consumption activities along the milk value chain and design strategies to minimize them. Corn, sorghum and lucerne production under irrigation in the greater Orange River basin is sustainable, whereas oats production for silage in the same catchment area is not sustainable. Our findings provide the rationale for dairy producers and water users in the dairy industry to get an understanding of the degree of sustainability of their input and output combinations, production choices, and policy interventions, in terms of water use.

Description: Strontium and barium to calcium ratios are often used as proxies for tracking animal movement across salinity gradients. Many estuarine rivers face saltwater intrusion due to sea level rise, potentially causing changes in mobility and distribution of these metals upstream. From May 2013 to August 2015, monthly water samples were collected and in-situ measurements were performed at six sites along an estuary strongly affected by saltwater intrusion, the Calcasieu River, with salinity ranging from 0.02 to 29.50 Parts Per Thousand (ppt). Results showed that the total Sr concentration and the Sr/Ca ratio both increased significantly with increasing salinity. The average Sr concentration at the site closest to the Gulf of Mexico (Site 6) was 46.21 µmol/L, about 130 times higher than that of the site furthest upstream (Site 1, 0.35). The average Sr/Ca ratio at Site 6 (8.41 mmol/mol) was about three times the average Sr/Ca ratio at Site 1 (2.89). However, the spatial variation in total Ba concentration was marginal, varying from 0.36 to 0.47 µmol/L. The average Ba/Ca ratio at Site 1 (4.82 mmol/mol) was about 54 times the ratio at Site 6 (0.09), showing a negative relation between the Ba/Ca ratio and salinity. All elemental concentrations and ratios had considerable seasonal variations, with significant differences among sampling months for the Sr and Ba concentrations and the Ba/Ca ratio (p 〈 0.01). The results suggest that for low-gradient estuarine rivers such as the Calcasieu River, water chemistry upstream would experience substantial Sr and Ca enrichment, potentially affecting aquatic environments and biological communities.

Description: Drought has been a recurrent phenomenon in Mexico. For its assessment and monitoring, several studies have monitored meteorological droughts using standardized indices of precipitation deficits. Such conventional studies have mostly relied on rain gauge-based measurements, with the main limitation being the scarcity of rain gauge spatial coverage. This issue does not allow a robust spatial characterization of drought. A recent alternative for monitoring purposes can be found in satellite-based remote sensing of meteorological variables. The main objective of this study is to evaluate the standardized precipitation index (SPI) in Mexico during the period 1998 to 2013, using the Tropical Rainfall Measuring Mission (TRMM) satellite product 3B42. Results suggest that Mexico experienced the driest conditions during the great drought between 2011 and 2012; however, temporal variability in the SPI was found across different climatic regions. Nevertheless, a comparison of the SPI derived by TRMM against the rain gauge-based SPI computed by the official Mexican Drought Monitor showed low to medium correlation of the time series though both SPIs managed to capture the most relevant droughts at the national scale. We conclude that the TRMM product can properly monitor meteorological droughts despite its relative short dataset length (~15 years). Finally, we recommend an assimilation of rain gauge and satellite-based precipitation data to provide more robust estimates of meteorological drought severity.

Description: 3D hydrological modeling was performed, using CATHY (acronym for CATchment HYdrology model), with the basic objective of checking whether the model could reproduce the effects of subsurface agricultural drainage on stream flows and soil water storage. The model was also used to further our understanding of the impact of soil hydrodynamic properties on watershed hydrology. Flows simulated by CATHY were consistent with traditional subsurface drainage approaches and, for wet years, flows at the outlet of the study watershed corroborated well with observed data. Temporal storage variation analyses illustrated that flows depended not only on the amount of rainfall, but also on its distribution throughout the year. Subsurface agricultural drainage increased base and total flows, and decreased peak flows. Hydrograph separation using simulated results indicated that exfiltration was the most dominant process; peak flows were largely characterized by overland flow; and subsurface drain flow variations were low.

Description: Urban flooding is of growing concern due to increasing densification of urban areas, changes in land use, and climate change. The traditional engineering approach to flooding is designing single-purpose drainage systems, dams, and levees. These methods, however, are known to increase the long-term flood risk and harm the riverine ecosystems in urban as well as rural areas. In the present paper, we depart from resilience theory and suggest a concept to improve urban flood resilience. We identify areas where contemporary challenges call for improved collaborative urban flood management. The concept emphasizes resiliency and achieved synergy between increased capacity to handle stormwater runoff and improved experiential and functional quality of the urban environments. We identify research needs as well as experiments for improved sustainable and resilient stormwater management namely, flexibility of stormwater systems, energy use reduction, efficient land use, priority of transport and socioeconomic nexus, climate change impact, securing critical infrastructure, and resolving questions regarding responsibilities.

Description: An urban rainfall-runoff water quality model was developed to simulate total suspend solids (TSS) using the stormwater management model (SWMM) for a 3.8 ha university campus in Beijing (approximately 76.5% impervious), and calibrated and validated against data from two observed rainfall events (221.2 and 16.6 mm rainfall). Model performance is satisfactory (Nash–Sutcliffe model efficiency 0.8 and 0.72 for flow and 0.74 and 0.51 for TSS concentration, respectively). A series of sensitivity model runs were conducted using the calibrated SWMM to study the influences of rainfall characteristics (rainfall hyetographs, depths and durations) and surface flooding on the TSS concentration in outlet runoff of the catchment. The Pilgrim and Cordery rainfall distribution defines a first-quartile storm (the most severe) and results in the highest peak discharge and TSS concentration at the outlet but the lowest outlet TSS load because of the highest TSS flood loss (32.3%). The simulated TSS pollutograph resulting from the Keifer and Chu rainfall distribution (with r = 0.5) is almost identical to that resulting from the alternating block rainfall distribution. Under the same rainfall hyetograph, simulated peak discharge and outlet TSS load are positively correlated (R2 = 0.95) to the rainfall depth as a function of the return period.

Description: The Storm Water Management Model (SWMM) is a dynamic simulation engine of flow in sewer systems developed by the USEPA. It has been successfully used for analyzing and designing both storm water and waste water systems. However, despite including some interfacing functions, these functions are insufficient for certain simulations. This paper describes some new functions that have been added to the existing ones to form a library of functions (Toolkit). The Toolkit presented here will allow the direct modification of network data during simulation without the need to access the input file. To support the use of this library, a testing protocol was performed in order to evaluate both calculation time and accuracy of results. Finally, a case study is presented. In this application, this library will be used for the design of a sewerage network by using a genetic algorithm based on successive iterations.

Description: Stream flow plays a crucial role in the environment, society, and the economy, and identifying the causes of changes in runoff is important to understanding the impact of climate change and human activity. This study examines the variation trends in recorded runoff for the Xinshui River, a tributary of the Yellow River on the Loess Plateau, and uses hydrological simulations to investigate how climate change and human activity have contributed to those trends. Results show that the recorded runoff at the Daning station on the Xinshui River declined significantly from 1955–2008 with an abrupt change occurring in 1973. The Simplified Water Balance Model (SWBM) simulates monthly discharge well with a Nash–Sutcliffe efficiency (NSE) coefficient of 78% and a relative error of volumetric fit (RE) of 0.32%. Runoff depth over the catchment in 1973–2008 fell by 25.5 mm relative to the previous period, with human activity and climate change contributing 60.6% and 39.4% of the total runoff reduction, respectively. However, the impacts induced by climate change and human activities are both tending to increase. Therefore, efforts to improve the ecology of the Loess Plateau should give sufficient attention to the impacts of climate change and human activity.

Description: Estimating the spatial distribution of precipitation is an important and challenging task in hydrology, climatology, ecology, and environmental science. In order to generate a highly accurate distribution map of average annual precipitation for the Loess Plateau in China, multiple linear regression Kriging (MLRK) and geographically weighted regression Kriging (GWRK) methods were employed using precipitation data from the period 1980–2010 from 435 meteorological stations. The predictors in regression Kriging were selected by stepwise regression analysis from many auxiliary environmental factors, such as elevation (DEM), normalized difference vegetation index (NDVI), solar radiation, slope, and aspect. All predictor distribution maps had a 500 m spatial resolution. Validation precipitation data from 130 hydrometeorological stations were used to assess the prediction accuracies of the MLRK and GWRK approaches. Results showed that both prediction maps with a 500 m spatial resolution interpolated by MLRK and GWRK had a high accuracy and captured detailed spatial distribution data; however, MLRK produced a lower prediction error and a higher variance explanation than GWRK, although the differences were small, in contrast to conclusions from similar studies.

Description: Climate, weather and water hazards do not recognize national boundaries. Transboundary/regional programs and cooperation are essential to reduce the loss of lives and damage to livelihoods when facing these hazards. The development and implementation of systems to provide early warnings for severe weather events such as cyclones and flash floods requires data and information sharing in real time, and coordination among the government agencies at all levels. Within a country, this includes local, municipal, provincial-to-national levels as well as regional and international entities involved in hydrometeorological services and Disaster Risk Reduction (DRR). Of key importance are the National Meteorological and Hydrologic Services (NMHSs). The NMHS is generally the authority solely responsible for issuing warnings for these hazards. However, in many regions of the world, the linkages and interfaces between the NMHS and other agencies are weak or non-existent. Therefore, there is a critical need to assess, strengthen, and formalize collaborations when addressing the concept of reducing risk and impacts from severe weather and floods. The U.S. Agency for International Development/Office of U.S. Foreign Disaster Assistance; the United Nations World Meteorological Organization (WMO); the WMO Southern Africa Regional Specialized Meteorological Center, hosted by the South African Weather Service; the U.S. National Oceanic and Atmospheric Administration/National Weather Service and the Hydrologic Research Center (a non-profit corporation) are currently implementing a project working with Southern Africa NMHSs on addressing this gap. The project aims to strengthen coordination and collaboration mechanisms from national to local levels. The project partners are working with the NMHSs to apply and implement appropriate tools and infrastructure to enhance currently operational severe weather and flash flood early warning systems in each country in support of delivery and communication of warnings for the DRR entities at the regional, national and local levels in order to reduce the loss of life and property.

Description: The Upper Indus Basin (UIB) and the Karakoram Range are the subject of ongoing hydro-glaciological studies to investigate possible glacier mass balance shifts due to climatic change. Because of the high altitude and remote location, the Karakoram Range is difficult to access and, therefore, remains scarcely monitored. In situ precipitation and temperature measurements are only available at valley locations. High-altitude observations exist only for very limited periods. Gridded precipitation and temperature data generated from the spatial interpolation of in situ observations are unreliable for this region because of the extreme topography. Besides satellite measurements, which offer spatial coverage, but underestimate precipitation in this area, atmospheric reanalyses remain one of the few alternatives. Here, we apply a proven approach to quantify the uncertainty associated with an ensemble of monthly precipitation and temperature reanalysis data for 1979–2009 in Shigar Basin, Central Karakoram. A Model-Conditional Processor (MCP) of uncertainty is calibrated on precipitation and temperature in situ data measured in the proximity of the study region. An ensemble of independent reanalyses is processed to determine the predictive uncertainty of monthly observations. As to be expected, the informative gain achieved by post-processing temperature reanalyses is considerable, whereas significantly less gain is achieved for precipitation post-processing. The proposed approach indicates a systematic assessment procedure for predictive uncertainty through probabilistic weighting of multiple re-forecasts, which are bias-corrected on ground observations. The approach also supports an educated reconstruction of gap-filling for missing in situ observations.

Description: Northeastern Mexico is a semiarid region with water scarcity and a strong pressure on water sources caused by the rapid increase of population and industrialization. In this region, rainwater harvesting alone is not enough to meet water supply demands due to the irregular distribution of rainfall in time and space. Thus, in this study the reliability of integrating rainwater harvesting with greywater reuse to reduce water consumption and minimize wastewater generation in the Tecnológico de Monterrey, Monterrey Campus, was assessed. Potable water consumption and greywater generation in main facilities of the campus were determined. Rainwater that can be potentially harvested in roofs and parking areas of the campus was estimated based on a statistical analysis of the rainfall. Based on these data, potential water savings and wastewater minimization were determined. Characterization of rainwater and greywater was carried out to determine the treatment necessities for each water source. Additionally, the capacity of water storage tanks was estimated. For the selected treatment systems, an economic assessment was conducted to determine the viability of the alternatives proposed. Results showed that water consumption can be reduced by 48% and wastewater generation can be minimized by 59%. Implementation of rainwater harvesting and greywater reuse systems in the Monterrey Campus will generate important economic benefits to the institution. Amortization of the investments will be achieved in only six years, where the net present value (NPV) will be on the order of US $50,483.2, the internal rate of return (IRR) of 4.6% and the benefits–investment ratio (B/I) of 1.7. From the seventh year, the project will present an IRR greater than the minimum acceptable rate of return (MARR). In a decade, the IRR will be 14.4%, more than twice the MARR, the NPV of US $290,412.1 and the B/I of 3.1, denoting economic feasibility. Based on these results, it is clear that integrating rainwater harvesting with greywater reuse resulted in a more feasible and reliable strategy than those strategies based only on rainwater harvesting. Furthermore, the investments can be amortized in a shorter period of time.

Description: Headwater streams generally comprise the majority of stream area in a watershed and can have a strong influence on downstream food webs. Our objective was to determine the effect of altering streamside management zone (SMZ) configurations on headwater aquatic insect communities. Timber harvests were implemented within six watersheds in eastern Kentucky. The SMZ configurations varied in width, canopy retention and best management practice (BMP) utilization at the watershed scale. Benthic macroinvertebrate samples collected one year before and four years after harvest indicated few differences among treatments, although post-treatment abundance was elevated in some of the treatment streams relative to the unharvested controls. Jaccard index values were similar across SMZ treatments after logging, indicating strong community overlap. These findings suggest that stream invertebrate communities did respond to the timber harvest, though not negatively. Results also suggest that SMZ criteria for aquatic habitats in steeply sloping topography, including at least 50 percent canopy retention and widths of at least 16.8 m, appear to be adequate for protecting benthic macroinvertebrate communities from logging impacts.

Description: Constructed ponds and wetlands are widely used in urban areas for stormwater management, ecological conservation, and pollution treatment. The treatment efficiency of these systems is strongly related to the hydrodynamics and hydraulic residence time. In this study, we developed a physical model and used rhodamine-WT as a tracer to conduct flume experiments. An equivalent Reynolds number was assumed, and the flume was a 1/25-scale model. Emergent obstructions (EOs), submerged obstructions (SOs), and high- and low-density emergent vegetation were placed along the sides of the flume, and 49 tracer tests were performed. We altered the density, spatial extent, aspect ratio, and configurations of the obstructions and emergent vegetation to observe changes in the hydraulic efficiency of a deep-water wetland. In the cases of low-aspect-ratio obstructions, the effects of the EOs on the hydraulic efficiency were significantly stronger than those of the SOs. In contrast, in the cases of high-aspect-ratio obstructions, the improvement effects of the EOs were weaker than those of the SOs. The high-aspect-ratio EOs altered the flow direction and constrained the water conveyance area, which apparently caused a short-circuited flow phenomenon, resulting in a decrease in hydraulic efficiency. Most cases revealed that the emergent vegetation improved the hydraulic efficiency more than the EOs. The high-density emergent vegetation (HEV) improved the hydraulic efficiency more than the low-density emergent vegetation (LEV). Three cases involving HEV, two cases involving LEV, and one case involving EOs attained a good hydraulic efficiency (λ > 0.75). To achieve greater water purification, aquatic planting in constructed wetlands should not be overly dense. The HEV configuration in case 3-1 achieved optimum hydraulic performance for compliance with applicable water treatment standards.

Description: The collection of hydrological data is particularly important for the utilization and management of water resources, water conservation, and flood control. Most of the hydrological observation operations should be conducted manually and are time-consuming, strenuous, dangerous, and have low precision. In this study, the shortcomings of the manual observations are overcome and the uncertainties related to the radar-based flow velocity estimations by a sensor in the radar surface current meter are explored. This includes an automatic observation feature and analyses are conducted using the radar signals that are received by the instruments for the real-time observation of the signals. In this study, experiments were conducted at the Water Resources Planning Institute (WRPI) of the Water Resources Agency, Ministry of Economic Affairs, Taiwan and the surface velocity was estimated using the conventional fast Fourier transform (FFT), wavelet transform (WT), and a bandpass filter. The experimental results after signal processing using the bandpass filter were precise, when the tilt angle ranged between 20 and 40 degrees. The 10.525 GHz radar surface current meter adopted in this study is suitable for a tilt angle of 20–40 degrees; the measurement error will be relatively large if the tilt angle is less than 20 degrees or more than 40 degrees.

Description: Implementing agricultural water management programs over appropriate spatial extents can have positive effects on water access and erosion management. Lack of access to water for domestic and agricultural uses represents a major constraint on agricultural productivity and perpetuates poverty and hunger in sub-Saharan Africa (SSA). This lack of access is the result of erratic precipitation, poor water management, limited knowledge of hydrological systems, and inadequate investment in water infrastructure. Water management programs should be made by multi-disciplinary teams that consider the interrelationship between hydraulic and anthropogenic factors. This paper proposes a method to prioritize watersheds for water management and agricultural development across Mali (Western Africa) using remote sensing data and GIS tools. The method involves deriving a set of relevant thematic layers from satellite imagery. Satellite images from Landsat ETM+ were used to generate thematic layers such as land use/land cover. Slope and drainage density maps were derived from Shuttle RADAR Topography Mission (SRTM) Digital Elevation Model (DEM) at 90 m spatial resolution. Population grids were available from the Global rural-urban mapping project (GRUMP) database for the year 2000 and mean rainfall maps were extracted from Tropical rainfall measuring mission (TRMM) grids for each year between 1988 and 2014. Each thematic layer was divided into classes that were assigned a rank for agriculture and livelihoods development provided by experts in the relevant field (e.g., Soil scientist ranking the soil classes) and published literature on those themes. Zones of priority were delineated based on the combination of high scoring ranks from each thematic layer. Five categories of priority zones ranging from “very high” to “very low” were determined based on total score percentages. Field verification was then undertaken in selected categories to check the priority assigned to each class using a random sampling method. Watershed boundaries were prepared at 1000 ha scale and overlaid on the priority map to identify watersheds that were in a very high priority zone. The importance and efficiency of using remote sensing to prioritize watershed interventions across countries is critical due to the limited technical and financial resources available in sub-Saharan Africa (SSA).

Description: Recently, urban areas have experienced frequent, large-scale flooding, a situation that has been aggravated by climate change. This study aims to improve the urban drainage system to facilitate climate change adaptation. A methodology and a series of mitigation strategies are presented to efficiently improve the urban drainage system in light of climate change. In addition, we assess the impact of climate change and predict the scale of potential future flood damage by applying the methodology and mitigation strategies to urban areas. Based on the methodology presented, urban flood prevention measures for Gyeyang-gu (Province), Incheon, Korea, was established. The validity of the proposed alternatives is verified by assessing the economic feasibility of the projects to reduce flood damage. We expect that the methodology presented will aid the decision-making process and assist in the development of reasonable strategies to improve the urban drainage system for adaptation to climate change.

Description: Channel-forming discharges typically are associated with recurrence intervals less than five years and usually less than two years. However, the actual frequency of occurrence of these discharges is often several times more frequent than the statistical expectation. This result was confirmed by using the Log-Pearson Type 3 statistical method to analyze measured annual series of instantaneous peaks and peak daily means for 150 catchments in six states in the North Central Region of the United States. Discharge records ranged from 39 to 102 years and catchment sizes ranged from 29 to 6475 km2. For each state, mean values of the ratio of the calculated to the expected occurrences exceeded 1.0, for recurrence intervals from two years to 100 years with R-squared values varying from 0.64 to 0.97, respectively. However, catchment-by-catchment variability was too large for the relationships for each state to be useful. We propose a method, called Full Daily Distribution (FDD), which used all of the daily values for the available period of records. The approach provided ratios of calculated to expected occurrences that were approximately 1.0. For recurrence intervals less than five years, the FDD calculated discharges were much greater than those obtained by using the Log-Pearson Type 3 approach with annual series of instantaneous peaks or peak daily means. The method can also calculate discharges for recurrence intervals less than one year. The study indicates a need to enhance the Log-Pearson Type 3 method to provide better estimates of channel-forming discharges and that the proposed FDD could be a useful tool to this purpose.

Description: Expolitation of coalbed methane (CBM) involves production of a massive amount saline water that needs to be properly managed for environmental protection. In this study, direct contact membrane distillation (DCMD) was utilized for treatment of CBM-produced water to remove saline components in the water. Simulated CBM waters containing varying concentrations of NaCl (1, 20, and 500 mM) and NaHCO3 (1 and 25 mM) were used as feed solutions under two transmembrane temperatures (Δ40 and 60 °C). In short-term distillation (~360 min), DCMD systems showed good performance with nearly 100% removal of salts for all solutes concentrations at both temperatures. The permeate flux increased with the feed temperature, but at a given temperature, it remained fairly stable throughout the whole operation. A gradual decline in permeate flux was observed at Δ60 °C at high NaHCO3 concentration (25 mM). In long-term distillation (5400 min), the presence of 25 mM NaHCO3 further decreased the flux to 25%–35% of the initial value toward the end of the operation, likely due to membrane fouling by deposition of Ca-carbonate minerals on the pore openings. Furthermore, pore wetting by the scalants occurred at the end of the experiment, and it increased the distillate conducitivity to 110 µS·cm−1. The precipitates formed on the surface were dominantly CaCO3 crystals, identified as aragonite.

Description: Due to the scarcity of field observations and geodetic measurements in catchments in the Karakoram Mountains in Western China, obtaining precipitation data for the high mountains involves large uncertainties and difficulties. In this study, we used a functional relationship between the annual glacier accumulation and summer temperature at the equilibrium line altitude (ELA) to derive precipitation lapse rates (PLAPSs) in a data-scarce watershed. These data were used in a modified Soil and Water Assessment Tool (SWAT) model with a glacier module to simulate glacio-hydrological processes in the Yarkant River basin in the Karakoram. The PLAPS based on the widely-used grid datasets considerably underestimated precipitation, yielding an unreasonable watershed water balance and inaccurate glacier changes. However, the ELA-based PLAPS improved the simulation significantly. In the Yarkant River basin, the annual precipitation reached a peak of 800–1000 mm at approximately 5300 m a.s.l. The model simulations indicated that the contributions of glacier melt and ice melt to total runoff were 52% and 31%, respectively. Moreover, a significant precipitation increase and a non-significant temperature increase during the melt season may be the major reasons for the decreased ice melt and slower glacier shrinkage on the northern slope of the Karakoram during the period of 1968–2007.

Description: Most studies of input data used in hydrological models have focused on flow; however, point discharge data negligibly reflect deviations in spatial input data. To study the effects of different input data sources on hydrological processes at the catchment scale, eight MIKE SHE models driven by station-based data (SBD) and remote sensing data (RSD) were implemented. The significant influences of input variables on water components were examined using an analysis of the variance model (ANOVA) with the hydrologic catchment response quantified based on different water components. The results suggest that compared with SBD, RSD precipitation resulted in greater differences in snow storage in the different elevation bands and RSD temperatures led to more snowpack areas with thinner depths. These changes in snowpack provided an appropriate interpretation of precipitation and temperature distinctions between RSD and SBD. For potential evapotranspiration (PET), the larger RSD value caused less plant transpiration because parameters were adjusted to satisfy the outflow. At the catchment scale, the spatiotemporal distributions of sensitive water components, which can be defined by the ANOVA model, indicate that this approach is rational for assessing the impacts of input data on hydrological processes.

Description: To understand changes in global mean and extreme streamflow volumes over recent decades, we statistically analyzed runoff and streamflow simulated by the WBM-plus hydrological model using either observational-based meteorological inputs from WATCH Forcing Data (WFD), or bias-corrected inputs from five global climate models (GCMs) provided by the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP). Results show that the bias-corrected GCM inputs yield very good agreement with the observation-based inputs in average magnitude of runoff and streamflow. On global average, the observation-based simulated mean runoff and streamflow both decreased about 1.3% from 1971 to 2001. However, GCM-based simulations yield increasing trends over that period, with an inter-model global average of 1% for mean runoff and 0.9% for mean streamflow. In the GCM-based simulations, relative changes in extreme runoff and extreme streamflow (annual maximum daily values and annual-maximum seven-day streamflow) are slightly greater than those of mean runoff and streamflow, in terms of global and continental averages. Observation-based simulations show increasing trend in mean runoff and streamflow for about one-half of the land areas and decreasing trend for the other half. However, mean and extreme runoff and streamflow based on the GCMs show increasing trend for approximately two-thirds of the global land area and decreasing trend for the other one-third. Further work is needed to understand why GCM simulations appear to indicate trends in streamflow that are more positive than those suggested by climate observations, even where, as in ISI-MIP, bias correction has been applied so that their streamflow climatology is realistic.

Description: Water has often been the source of crises and their frequency will intensify due to climate change impacts. The Niagara River Watershed provides an ideal case to study water crises as it is an international transboundary system (Canada-United States) and has both historical and current challenges associated with water quantity and quality, which resonates broadly in water basins throughout the world. The aim of this study was to understand how stakeholders perceive ecosystems and the relationship with preferences for governance approaches in the context of water governance. An online survey instrument was employed to assess perceptions of the system in terms of resilience (engineering, ecological, social-ecological, or epistemic), preferences for governance approaches (state, citizen, market, and hybrid forms), and the most pressing issues in the watershed. Responses showed that, despite demographic differences and adherence to different resilience perspectives, support was strongest for governance approaches that focused on state or state-citizen hybrid forms. The validity of the resilience typology as a grouping variable is discussed. The roles of institutional constraints, pragmatism in governance approach preferences, and the influence of multiple crises are explored in relation to the context of the study site, as well as to water governance scholarship more broadly.