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• Water diplomacy is multi-track with informal tracks involving foreign affairs and security actors • Informal water diplomacy has a role to inform and share knowledge on shared rivers • Informal water diplomacy can extend beyond the geographical scope of the river • The efficacy of water diplomacy is related to the political economy of water Water diplomacy is regarded as a means to prevent conflict and to enhance peace through the cooperative management of transboundary water resources. There have been calls for water diplomacy to be given further attention, especially by foreign policy and security specialists, and to be extended to non-state actors through informal dialogue processes. The paper critically questions the qualitative changes water diplomacy delivers and argues for further analytical scrutiny on its efficacy. Using a critical hydropolitics perspective, the paper advances understanding of the way power asymmetries presiding over contested waters are altered or maintained, particularly through informal diplomacy. To exemplify, the paper uses Track 2 diplomacy or an informal dialogue process between non-state actors. Drawing on the case study of the Track 2 process by the Council for Security Cooperation in the Asia Pacific, the paper examines how foreign affairs experts deliberated water security in the Mekong river basin in the face of rapid dam development. The analysis demonstrates that information was forwarded to officials within the ministry of foreign affairs and created alternative knowledge channels, differentiated from networks of water and environmental ministries. Informal diplomacy also enabled downstream states, usually considered to have less influence on issues of water allocation, to exercise power in agenda-setting and influencing the debate. However, flows of finance around dam development within the region made it difficult for informal diplomacy to provide alternatives to existing transboundary water arrangements such that it changes power relations manifested in formal diplomacy. The paper suggests attentive analysis on the links between state and non-state actors through informal diplomacy and the nuanced way resources and networks are mobilised to control water resources. [ABSTRACT FROM AUTHOR]

The Delaware River Basin (DRB) in the Mid-Atlantic region of the United States is an institutionally complex water resources system that provides drinking water for 13.5 million people, plus water for energy, industry, recreation, and ecosystems. This paper introduces Pywr-DRB, an open-source Python model exploring the impacts of reservoir operations, transbasin diversions, and minimum flow targets on water availability and drought risk in the DRB. Pywr-DRB draws on streamflow estimates from emerging data resources, bridging advances in large-scale hydrologic modeling with an improved representation of the basin's evolving water infrastructure and management institutions. Our detailed model diagnostic assessment demonstrates that Pywr-DRB provides substantial improvements over sole use of hydrologic models in capturing the DRB's dynamics. We also explore how water management alters model-derived risk estimates for low flows and water demand shortfalls. Our approach to diagnostic benchmarking and water systems modeling is broadly applicable to other major basins. • Pywr-DRB enables open science & drought risk planning for the Delaware River Basin. • Pywr-DRB bridges hydrologic model data, observations & water management modeling. • Reservoirs, diversions & minimum flow targets shape low-flow behaviors in the basin. • Reliability of minimum flows & transbasin diversions are strongly interdependent. • Water management modeling is critical for accurate water availability assessment. [ABSTRACT FROM AUTHOR]

• Groundwater contributes 26–78 % of streamflow during the low-flow period in a large Himalayan watershed. • The groundwater contribution varies substantially from the upstream to downstream sub-catchments. • Young water fraction ranges from 36 % in the middle catchment to 55 % in the lower catchment. • Hydraulic conductivity of the underlying bedrock is a key control on groundwater discharge to the stream. • Our study emphasizes fractured bedrock's critical role in mountain baseflow. Mountains in general are important sources of water resources and correspondingly, the Upper Indus Basin (UIB) in the Himalayas provides water for hundreds of millions of users. During low-flow periods, streamflow is fed by a combination of groundwater (baseflow), snow/glacier melt and recent precipitation. However, the proportion of stream baseflow generated by different sources and the factors that control these contributions remain poorly understood. In this paper, we focus on the Western Himalayan Liddar watershed (1243 km2) in the UIB and use a multi-method approach to characterize aquifers and baseflow generation in three nested catchments which represent varying geology and topography. Our multi-method approach includes geophysical surveys, slug tests, stable isotope compositions, young water fraction (F yw) estimation and a Bayesian end member mixing model. Specifically, we hypothesize that K sat of the subsurface plays a critical role in the contribution of groundwater to baseflow. The watershed is subdivided into three nested catchments (Limestone, hardrock and alluvium). Our results indicate that the upstream, steep, high-permeability limestone catchment has the relatively largest groundwater contribution to streamflow (63–78 %) and a low F yw (38 %) than the other two sites. The mid-elevation hard rock catchment has a lower permeability on average but is highly variable due to fracture networks and geologic contacts, allowing a substantial groundwater contribution to streamflow (38–66 %) and a similar F yw (36 %) to the limestone catchment. The downstream, low-slope catchment underlain by alluvium has a highly variable hydraulic conductivity and a substantially lower groundwater contribution to streamflow (26–45 %) and a higher F yw (55 %). We find that both hydraulic conductivity and topography exert control on the magnitude of baseflow contribution to the stream. However, K sat acts as a key control in groundwater contribution to baseflow as observed in headwaters and downstream region of the watershed. While unconsolidated deposits are often thought of as important high-porosity mountain aquifers, our results point to the importance of fractured and karstified bedrock in baseflow generation in high mountains. As climate change alters the snow- and ice-melt regimes of UIB rivers, our study underscores the critical importance of improving our understanding of baseflow sources. [ABSTRACT FROM AUTHOR]

Examining the interplay among water-energy-environment-economy in the Yellow River Basin holds paramount importance for ecological conservation and fostering the high-quality advancement in this region. This research establishes a theoretical framework for understanding the water-energy-environment-economy interplay and proposes a comprehensive evaluation index system targeting for holistic development of the water-energy-environment-economy system. Analyzing data from 57 cities in the Yellow River Basin in 2002–2022, this research employes the coupling coordination model, spatial autocorrelation model, and obstacle model for in-depth analysis. The findings indicate: (1) The overall development of water-energy-environment-economy in the Yellow River Basin demonstrates a steady upward trajectory, with distinct evolution patterns in each subsystem. (2) The coupling coordination degree in water-energy-environment-economy exhibits a gradual improvement, with the coupling coordination values showing the sequence of Lower reaches > Upper reaches > Total average > Middle reaches. (3) Coupling coordination degree reveals a spatial pattern of high values in peripheries and lower values in the central areas, suggesting a certain spatial agglomeration. (4) Water resources per capita emerges as the primary obstacle factor in the Yellow River Basin, with its obstacle degree on the rise. Building upon these insights, the paper presents targeted policy recommendations. • A theoretical framework for relationship among water, energy, environment, and economy is built. • Coupling coordination degree of WEEE in the YRB was evaluated. • Spatiotemporal evolution of WEEE coupling coordination was analyzed. • Obstacle factors of WEEE were identified in the YRB. [ABSTRACT FROM AUTHOR]

Soke Plain, located within the Büyük Menderes River Basin is one of the highest producers of cotton in Türkiye. The overall irrigation water supply is based on scarce conventional water resources that are being depleted at an increasing pace due to climate change impacts in B. Menderes. The inclusive objective of this research is to pave the way for a "water efficiency action plan" incorporating non-conventional (alternative) water resources for irrigation in Soke Plain to address adaptive management. Integrated Water Resources Management (IWRM) principles help decision makers (DMs) to identify and apply the most adequate alternatives among other possible ones in resource planning processes. Therefore, the preference ranking of DMs among possible water resource alternatives for irrigation is vital for implementation. This paper marks the first instance of using a multi-criteria decision-making (MCDM) method to evaluate both conventional and non-conventional water resource alternatives for cotton irrigation. The evaluation and ranking of water resource alternatives is processed using the hybrid MCDM method, integration of "Hesitant Fuzzy-Analytic Hierarchy Process" (HF-AHP) and "Hesitant Fuzzy Evaluation based on Distance from Average Solution" (HF-EDAS), namely HF-AHP-EDAS. This procedure implies several possibly contradictory qualitative and quantitative criteria, incorporates ambiguity, vagueness, and hesitancy in decision-makers' decisions, and achieves a consistent, dependable ranking of alternatives. Eight different water resources for irrigation are evaluated by 5 experts, for 15 assessment criteria, in Soke Plain. Conventional water resources blended with drainage water is concluded to be the best irrigation water resource alternative, with HF-AHP-EDAS and also with HF-AHP-PROMETHEE II (Preference Ranking Organization Method for Enriching Evaluations II), that is used for comparison analysis. This choice aligns well with the outlined arguments, culminating in an overall result deemed compliant with the field survey. [Display omitted] • B. Menderes is an example of water stressed river basin (water stress index > 0,8). • Knowing preference ranking of DMs for irrigation resources helps to restructure water management. • Using an MCDM method to evaluate irrigation water alternatives marks the first instance. • The HF-AHP-EDAS and HF-PROMETHEE II methods are utilized to rank irrigation water alternatives. • Reuse necessitates associated sewerage infrastructure, quality standards and pricing policy. [ABSTRACT FROM AUTHOR]

This paper engages in a normative analysis of water security, in view of the sustainable development goals (SDGs) and the call for transformation. It examines the role of river basin organizations (RBOs) and integrated water resources management (IWRM) to water governance, and the extent to which they are consistent with water security for development in Southern Africa. The paper uses Policy Coherence for Development (PCD) and addresses essential questions regarding the extent to which RBOs in the Southern African Development Community (SADC) insofar as concerns SDG 6 achieve water security for people at the grassroots. The theoretical contribution of the paper includes the comparative examination of normative PCD and water security structures at RBO level in Southern Africa, and the extent to which RBOs reflect IWRM principles. Empirically, the paper highlights regional water policies regarding harmonization and coordination in the respective riparian states of and the RBOs, in line with the SADC's developmental objectives. As RBOs seem to prefer conserving, developing and utilizing water resources over people, they would do well to shift their focus on to people by adopting normative PCD, if they are to witness transformation. This would also be consistent with regional goals, which seek to bring the transformation agenda to the ground. • The SDGs suggest that development should be realized through "transformation". • Theoretically, normative PCD and water security are compared, and how far they reflect IWRM principles. • Empirically, harmonization and coordination of water policies of riparian states in basin organizations are highlighted. • SADC's commitment to IWRM integrates core values essential for transformation in some of its key policy documents. • The core values have not been translated into SADC river basins' water resources management strategies. [ABSTRACT FROM AUTHOR]

• This paper constructed a framework for green water assessment in the Loess Plateau gully region using MIKE SHE model. • A new concept and extraction method for green water components was defined based on existing research. • A new concept of the potential of green water was defined in relation to the dried soil layers' classification indicators. • We assessed the dependence on green water components and potential for environmental changes. Exponentially increasing water demand and increasingly uncertain hydrological conditions due to climate change (CC) and land use/cover change (LUCC) undoubtedly pose significant challenges to the sustainability of water systems in arid and semi-arid regions worldwide, and even more so in the rain-fed agricultural area of the Loess Plateau (LP) in China, where green water supports all ecological landscapes and most agriculture. Therefore, an accurate assessment of green water resources is crucial for regional development. This paper constructed a comprehensive framework for assessing green water resources based on the MIKE SHE model, defined a new concept of green water components (GWCs) that can be extracted based on existing studies, proposes the potential of green water (GW P), and present a research methodology. To validate this research framework, we applied it to a typical basin in the LP gully area of the Nanxiaohegou (NXHG) basin. The model was calibrated using runoff data from basin outlet stations to extract four GWCs: high-efficiency green water (GW H), low-efficiency green water (GW L), unused green water (GW U), ineffective green water (GW I). We then assessed the GW P of the basin and analyzed its trends, consistency, and dependence on changing environments. The assessment framework is simple and easy to use, providing valuable information for regional revegetation and basin water management, and is highly recommended for replication in other regions. [ABSTRACT FROM AUTHOR]

Research on water cooperation in the Eastern Nile Basin has focused on expanding policy and diplomacy tools for a better allocation of transboundary water resources confined to the river. Regional cooperation on water and related sectors such as energy and land expands the bargaining and areas for mutual gain, and thus enhances cooperation perspectives. This paper looks at the contribution and the potential benefits of a regional cooperation approach to addressing the underlying challenges of water diplomacy, such as complexity and distrust. It also promotes the understanding of river basins as a “resource basin” of integrated and linked resource-use issues, not always related to the river flow. The paper provides an analysis of priority issues for water–energy–food nexus in regional cooperation in the Eastern Nile Basin. This basin represents an illustrative case for regional cooperation and increased integration due to multiple comparative advantages inherent in the uneven endowments of water, energy and arable land resources, and to varying levels of economic and technological advancement among the three riparian countries: Egypt, Sudan and Ethiopia. The paper also analyzes institutional arrangements on a regional scale, and elaborates on the inherent trade-offs associated with them. [ABSTRACT FROM AUTHOR]

• Actual evapotranspiration and water stress during the dry seasons were studied. • The SSEBop model's performance can be improved by readjusting aerodynamic resistance. • All land-cover classes, especially farmland areas experienced severe water stress. Due to the simultaneous impacts of economic development and climate change, the Lijiang River Basin in China—the largest karst tourist attraction in the world—has experienced dramatic water shortages during the dry season. As actual evapotranspiration (ET a) plays a critical role in the water cycle, accurate estimation of ET a and water stress are important for sustainable water resources management. In this paper, we mapped the distribution of daily ET a using a modified Operational Simplified Surface Energy Balance (SSEBop) model in combination with Landsat 8 images and assessed water stress using the Crop Water Stress Index (CWSI) during the dry season in the Lijiang River Basin. In general, the daily ET a simulated by the SSEBop model with aerodynamic resistance value of 110 s m−1 was higher than that of satellite-based actual evapotranspiration products (i.e., MOD16A2 and Penman-Monteith-Leuning (PML)_V2 actual evapotranspiration products in this study). Aerodynamic resistance plays a critical role in the estimation of energy fluxes in the SSEBop model and should be readjusted and calibrated with available datasets to improve the model's performance in estimating actual evapotranspiration for particular regions. Readjusted values between 20 and 35 s m−1 of aerodynamic resistance produced reasonable agreement with satellite-based actual evapotranspiration products in the Lijiang River Basin. In addition, insufficient ground-level measurements of actual evapotranspiration might have increased the uncertainty of the SSEBop model's performance. The achievement of higher accuracy in the estimation of actual evapotranspiration and water availability will require establishing local flux towers, particularly in forested areas, to collect evapotranspiration, temperature and other in situ data. For different land-cover classes, forest areas exhibited the highest actual evapotranspiration, whereas farmland and built-up areas had the lowest actual evapotranspiration values compared to the other land-cover classes. All land-cover classes, especially farmland areas, experienced severe water stress. Inadequate precipitation as a result of climate change, combined with high actual evapotranspiration will result in less water being available for the Lijiang River Basin. Additional water is required to compensate for evapotranspiration and support plant growth in the Lijiang River Basin during the growing season. [ABSTRACT FROM AUTHOR]

In federations such as the United States, governments at various levels are experimenting with new watershed governance arrangements to protect water quality for both ecosystem health and human consumption. Such arrangements may bring previously uncooperative governments together to credibly commit to resource protection under the auspices of new and intricate formal institutions. Given the risks of cooperation, theory indicates that a robust arrangement will contain means of holding governing actors accountable to each other. This paper examines a purportedly successful case, the New York City watershed governance arrangement, to identify how safeguards against intergovernmental opportunism promote lasting cooperation. Using the qualitative method of process tracing, this paper finds that the New York City watershed governance arrangement uses structural, judicial, and popular safeguards against opportunistic behaviors by governing actors that might threaten the resource or the arrangement. The results indicate that such safeguards are present and interact with other safeguards and rule institutions at the state and federal level to maintain compliance. [ABSTRACT FROM AUTHOR]

Important hydrological changes are observed in Serbia, as well as in many parts of the world. Many national and international projects and studies address climate change and its impact on water resources. Some focus solely on the impact of climate change, while others also assess the impact of land use changes and/or changes in human use of water. Due to differences in climate change and human activities, the different climate and hydrological trends are obtained for the different regions in Serbia. This paper presents the past longterm temperature, precipitation and river discharge trends across Serbia. Second, more important aim of the research, is to assess and forecast average relationships between an increase in air temperature and changes in river discharges and precipitation. This relation could help us to find appropriate regional climate and hydrological models. Even within a single catchment, depending on the regional models used, the initial and other assumptions made, and the impacts assessed, the differences between the results can be small but often significant, too. The reliability of the projections receives little or no consideration. This paper also discusses this topic and attempts to provide some guidelines. [ABSTRACT FROM AUTHOR]

Frequent drought disasters have significant impacts on socio-economic and ecosystems, and it is crucial to explore the propagation characteristics of drought for disaster prevention and mitigation. In this paper, based on 0.25° × 0.25° grid-point Meteorological hydrological and large-scale climate factor data, the start-to-start, peak-to-peak, and end-to-end drought propagation times, and the periods and rates of drought development and recovery were estimated for 11 regions in the Luanhe River Basin under stationary and non-stationary conditions. The Generalized Additive Model for Location, Scale and Shape (GAMLSS) framework was used to construct stationary and non-stationary models to capture the stationary and non-stationary drought characteristics respectively, and then the drought development and recovery patterns, and drought propagation times were assessed. The results showed that under the influence of climate factors, severe drought events occurred in most study areas, the duration of meteorological drought was prolonged by 0.1–0.6 months, and the peak intensity was increased by about 0.05. The severity of hydrological drought increased by 0.2–0.8, and the peak intensity decreased by 0.1–0.2. The rate of development and recovery of hydrological drought was accelerated by 0.1–0.2 per month. The propagation time of start-to-start was shortened by 0.2 months, and the propagation time of end-to-end was extended by 1–2 months. These mean that water resource control authorities need to propose responses to droughts more quickly. • The non-stationary drought indices considering climatic factors were constructed. • The drought propagation time was calculated from start to start, peak to peak, and end to end. • Quantification of the effects of climate change on drought propagation [ABSTRACT FROM AUTHOR]

Considering global water scarcity, especially in the agricultural sector, many attempts are being made to improve water productivity and save more water. Changing irrigation systems from surface to pressurized has been one of the considerable actions in this regard. However, any attempts to do so must be evaluated in an integrated perspective at the basin level by means of relevant agro-hydrological models before making them operational. This paper aims to address this issue by using the soil and water assessment tool (SWAT). Zarrineh Rud River, the main feeding river of northwest Iran’s Lake Urmia, is selected as the case study for exploring this methodology. This lake has been shrinking since 1995, and to save water and increase the basin’s water productivity, improvement of pressurized systems is considered as a solution. SWAT cannot directly simulate changing the irrigation system from surface to pressurized. In this study, we use the innovative approach of applying the model to simulate different irrigation systems considering real irrigation management variables such as depth and date of each irrigation event. Also, in order to improve its performance in simulation of such systems, a comprehensive calibration procedure was used based on a wide range of data for hydrological and agricultural variables. The results showed that changing the current irrigation to a pressurized system can increase water productivity up to 15% due to increases in crop yield, better water distribution and greater actual evapotranspiration. However, pressurized irrigation results in no significant change in total inflow to the lake. Notably, these systems can intensify drawdown of the basin’s water table up to 20%. So, any significant “real water saving” program in the basin must be associated with reduction of evapotranspiration by adopting measures like reducing cultivated areas, changing cropping patterns to less water consuming plants, or applying deficit irrigation. The applied methodology of this paper as well as the comprehensive calibration and setup of the SWAT model with the readily available hydrological and agricultural variables can be a good sample for similar works. However, further work is still needed to more broadly test this approach in areas with intensive irrigation systems. [ABSTRACT FROM AUTHOR]

• The adaptive irrigation behaviors might worsen the water scarcity in the CRB. • Clustering identified bold, prudent, and forward-looking farmer classes. • We indicated specific parameters for uncertainty reduction in human systems. The Colorado River Basin (CRB) supports the water supply for seven states and forty million people in the Western United States (US) and has been suffering an extensive drought for more than two decades. As climate change continues to reshape water resources distribution in the CRB, its impact can differ in intensity and location, resulting in variations in human adaptation behaviors. The feedback from human systems in response to the environmental changes and the associated uncertainty is critical to water resources management, especially for water-stressed basins. This paper investigates how human adaptation affects water scarcity uncertainty in the CRB and highlights the uncertainties in human behavior modeling. Our focus is on agricultural water consumption, as approximately 80% of the water consumption in the CRB is used in agriculture. We adopted a coupled agent-based and water resources modeling approach for exploring human-water system dynamics, in which an agent is a human behavior model that simulates a farmer's water consumption decisions. We examined uncertainties at the system, agent, and parameter levels through uncertainty, clustering, and sensitivity analyses. The uncertainty analysis results suggest that the CRB water system may experience 13 to 30 years of water shortage during the 2019–2060 simulation period, depending on the paths of farmers' adaptation. The clustering analysis identified three decision-making classes: bold, prudent, and forward-looking, and quantified the probabilities of an agent belonging to each class. The sensitivity analysis results indicated agents whose decision-making models require further investigation and the parameters with the higher uncertainty reduction potentials. By conducting numerical experiments with the coupled model, this paper presents quantitative and qualitative information about farmers' adaptation, water scarcity uncertainties, and future research directions for improving human behavior modeling. [ABSTRACT FROM AUTHOR]

Summary Australia is the driest continent and there is increasing competition for scarce fresh water resources between agriculture and the environment. In the Murray–Darling Basin (MDB) that conflict has largely been resolved by reallocating water from agriculture to the environment. As part of the water reform process both governments and industry are focussed on improving on-property water use efficiency (WUE), particularly of irrigated agriculture. This paper examines the potential for WUE to enable MDB irrigators to adapt to cuts in their irrigation entitlements. The paper draws on data from a case study in the Namoi Valley of New South Wales. The distinctive contribution of this paper is that we draw on survey data of the existing and intended adoption of a limited suite of currently available WUE practices. That is, we have not simply assumed that all irrigators, or a specific proportion of irrigators, will adopt each WUE option. Given survey respondents’ intended level of adoption, we calculated the potential water savings for each property and then the catchment, without extrapolating beyond the survey respondents. Those calculations suggest that water savings of up to 100.9 GL could be achieved across the Namoi catchment if those interested in doing so were to convert to existing improved WUE practices. Those savings represented 82% of the reduction in irrigator entitlements under the draft MDB Plan, and exceed the 10 GL/yr reductions required under the revised MDB Plan. These results suggest that those adopting existing WUE practices will have additional water for irrigation. To the extent that this is the case, there seems to be less justification for government support for irrigators during the adjustment process. [ABSTRACT FROM AUTHOR]

Summary Unraveling the interaction between water users in a river basin is essential for sound water resources management, particularly in a context of increasing water scarcity and the need to save water. While most attention from managers and decision makers goes to allocation and withdrawals of surface water resources, reuse of non-consumed water gets only marginal attention despite the potentially significant volumes. As a consequence, claims of water saving are often grossly exaggerated. It is the purpose of this paper to explore the processes associated with water reuse in a river basin among users of varying nature and review existing methods for directly or indirectly describing non-consumed water, recoverable flow and/or water reuse. First a conceptual representation of processes surrounding water withdrawals and associated definitions is discussed, followed by a section on connectivity between individual withdrawals and the complex dynamics arising from dependencies and tradeoffs within a river basin. The current state-of-the-art in categorizing basin hydrological flows is summarized and its applicability to a water system where reuse occurs is explored. The core of the paper focuses on a selection and demonstration of existing indicators developed for assessing water reuse and its impacts. It is concluded that although several methods for analyses of water reuse and recoverable flows have been developed, a number of essential aspects of water reuse are left out of existing indicators. Moreover, a proven methodology for obtaining crucial quantitative information on recoverable flows is currently lacking. Future studies should aim at spatiotemporal tracking of the recoverable portion of water withdrawals and showing the dependency of multiple water users on such flows to water policy makers. [ABSTRACT FROM AUTHOR]

Summary The effects of climate change on water resources have been studied extensively throughout the world through the use of hydrologic models coupled with General Circulation Model (GCM) output or climate sensitivity scenarios. This paper examines the effects of hydrologic model parameterization uncertainty or equifinality, where multiple unique hydrologic model parameter sets can result in adequate calibration metrics, on hydrologic projections from downscaled GCMs for three snowmelt-dependent watersheds (upper reaches of the Clearwater, Gunnison, and Sacramento River watersheds) in the western United States. The hydrologic model used in this study is the Soil and Water Assessment Tool (SWAT) and is calibrated for discharge at the watershed outlet in each watershed. Despite achieving similar calibration metrics, a majority of hydrologic projections of average annual streamflow during the 2080s were statistically different, with differences in magnitude and direction (increase or decrease) compared to historical annual streamflows. At the average monthly time-scale, a majority of the hydrologic projections varied in peak streamflow timing, peak streamflow magnitude, summer streamflows, as well as overall increases or decreases compared to the historical monthly streamflows. Snowmelt projections from the SWAT model also widely varied, both in depth and snowmelt peak timing, for all watersheds. Since a large portion of the runoff-producing regions in the western United States is snowmelt-dependent, this has large implications for the prediction of the amount and timing of streamflow in the coming century. This paper shows that hydrologic model parameterizations that give similar adequate calibration metrics can lead to statistically significant differences in hydrologic projections under climate change. Therefore, researchers and water resource managers should account for this uncertainty by assembling ensemble projections from both multiple parameter sets and GCMs. [ABSTRACT FROM AUTHOR]

Springs are environmental objects of unique character, determined by water resources and high water quality, important for economic, recreational, landscape, and cultural aspects. Springs, on the boundary of surface and groundwater resources, are fundamental for understanding resources and circulation of water in the river catchment, and can be good indicators for assessment of the natural environment changes. The paper presents results of discharge measurements analyses for 65 springs performed in the period 1946-2016 in the area of the Lublin Upland and Roztocze in Poland. Based on approximately 5,000 measurements, characteristic discharges were determined for each spring: minimum, mean, and maximum, as well as the variation coefficient. The role of spring waters in the alimentation of rivers was assessed. The most abundant springs (continuously or periodically exceed 100 dm3 · s–1, maximum discharge 400 dm3 · s–1) are alimented from the Cretaceous aquifer. The springs show high discharge stability in the multiannual rhythm and seasonal regime of water resource fluctuations resulting from the appearance of a series of years with increased or reduced atmospheric precipitation. Variable response to atmospheric alimentation results from the conditions of water flow through the aeration zone. Springs provide from 40% to almost 100% of river water. Because of economic activity, contributing to the transformation of environmental components and constituting a threat to springs, their niches, and water quality, there is the need for their protection and their preservation in a possibly natural state in accordance with the local environmental conditions. [ABSTRACT FROM AUTHOR]

'Water' always has been a key resource for humankind but over the period with increasing population and rapid urbanization, water resource is under immense pressure. Groundwater is the prime source of drinking water and needs proper monitoring in order to have an optimum utilization strategy owing to the current scenario of over-exploitation. Being the part of Deccan trap region, the basin is hot and semi-arid, experiencing moderately dry climate accompanied by episodic drought and erratic showers therefore, the surface water of the basin is ephemeral. In the present study, the probabilistic recharge zones have been delineated by dint of various thematic layers viz. geological setting, geomorphic features, land use, slope gradient, infiltration number, soil physiognomies, curvature and lineament through multi-criteria decision analysis technique in the GIS domain. This has further divided into four categories, viz., very poor, poor, good, and very good zones. Thus, this paper is an attempt to demarcate probabilistic groundwater zones in the Vaniar watershed region using geospatial techniques for better planning and management of groundwater resources. [ABSTRACT FROM AUTHOR]

Majority of researchers consider the Arabian-Caucasus region as a corridor for migration of earliest hominins from their African motherland to Eurasia. The paper is devoted to geological position of main stratified localities of the earliest Paleolithic industries in the Arabian-Caucasus region and estimation of environment of creators of these industries. The following early Paleolithic localities are analyzed: 'Ubeidiya in Israel, middle Orontes River, Halabiyeh-Zalabiyeh area in the Euphrates River valley, and Aïn al Fil in Syria, Dursunlu in Central Turkey, Şambayat, Bostancık, Eskimalatya, and Kovancılar in Eastern Turkey, Karakhach, Muradovo, Agvoric, and Jradzor in NW Armenia, Dmanisi in Southern Georgia, the Azykh cave in Nagornyi Karabakh, Muhkai II in Dagestan, and Kermek in the Taman Peninsula. The evolution of large and small mammals and palynological data on changes of vegetation from the Late Pliocene to the early Middle Pleistocene are studied to determine the age of the earliest Paleolithic industries and climatic conditions of that epoch. Combined analysis of paleontological, paleomagnetic and radio-isotopic data and geological correlation of the sections available for the Halabiyeh-Zalabiyeh, Şambayat, Kovancılar, Karakhach, Dmanisi, Muhkai II, and Kermek localities shows that their age is ranged in time interval ca. 2.0–1.7 Ma. The 1.7–1.6 Ma age of the lowest layers of 'Ubeidiya with Oldowan-type artefacts probably marks the end of this epoch. Removal of topographic effects of the late Calabrian and younger tectonic uplifts and offsets on major strike-slip faults shows that the topography of the late Gelasian – early Calabrian was much lower and less differentiated and main river systems were more passable than in the present time. The climate of the end of Gelasian was wet and relatively warm, with meadow-steppe and forest-steppe savanna-type vegetation in basins and valleys and coniferous and coniferous–broad-leaved forests in the mountains. Abundance of vegetation was supported by water resources of numerous rivers, lakes, and springs in the intermountain basins and valleys that were controlled partly by fault activity. This stimulated abundance of herbivorous mammals. In spite of relative aridisation at the beginning of Calabrian, vegetation continued to be freely available for herbivores. Hominin dispersal into the region was supported by rich resources of herbivores during the late Gelasian – early Calabrian time. [ABSTRACT FROM AUTHOR]

• The impact of precipitation, slope, and swamp wetland ratio on water yield is not affected by spatial scale and watershed. • Identifying key areas for ecosystem services combined with multiple scenarios can help to take ecological restoration. • The water yield in the Baihe basin is more sensitive on climate change, while the water yield in the Heihe basin is more easily affected by land use changes. • The economic development and ecosystem services can both be ensured by wetland ecological restoration. Water supply is one of the core ecosystem services functions for wetland. Due to the important status of Zoige wetland, assessment of water supply in Zoige wetland is significant for ecological security all over the world. In this paper, Heihe and Baihe basins in Zoige wetland were taken as research objects, the water yield module of the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model was used to spatially quantify water supply, with the aims of revealing the driving mechanism of water supply under different basins and spatial scale. We observed the spatial pattern change of water yield under baseline and eleven future scenarios and used the ANOVA of repeated measures and multiple linear regression model to explore the patterns and driving factors of water supply in Heihe and Baihe rivers basins. The research results were as follow. (1) The precipitation is main factor to improve water yield, but this intensity is different in different basins and spatial scale. Topography, climate, vegetation, and percentage of wetland conditions have important impacts on water yield services. However, the impacts of these conditions on water yield were various significantly across different watersheds and spatial scales (excluding factors such as precipitation, slope, and percentage of swamp wetland). (2) The spatial pattern of water yield main was affected by land use change and the amount of water yield main was affected by future climate change. (3) Water yield in the Baihe basin was more sensitive to climate change, while the Heihe basin is more sensitive to land use changes. Wetland ecological restoration strategies can effectively improve regional water yield, especially in the Heihe basin. (4) In all scenarios, the southeast regions of the study region were both the main hot spots of water yield. Wetland ecological restoration strategies have added hot spots in the north regions of the Baihe river basin, reduced hot spots in the middle-south regions of the Heihe basin. [ABSTRACT FROM AUTHOR]

• The evaluation index system of water resources intensive use is constructed. • The potential for water conservation and purification phases needs to be tapped. • The structure of spatial association network is sparse on the whole. • The technological element is the main reason for the formation of a spatially linked. Achieving the efficient, synergistic and sustainable utilization of water resources is a necessary precondition and an important means through which to protect the ecological environment of the Yellow River Basin (YRB) and promote the high-quality development of the basin's economy. This paper innovatively defines water-intensive utilization efficiency (WIUE) and constructs an appropriate evaluation index system. A superefficiency network slacks-based measure (SBM) model is introduced for measurement. The gravity model is improved, and the spatial clustering and spatial association network characteristics of water use efficiency (WUE) and water conservation and purification efficiency (WCPE) are analysed using exploratory spatial data analysis (ESDA) and social network analysis (SNA). Finally, the formation mechanism of the spatial network of WCPE is explored by using quadratic assignment procedure (QAP) regression. The following conclusions are obtained. (1) The WIUE of the YRB shows a divergent trend over time, with fluctuations in the water conservation and purification stage being the main factors influencing WIUE changes in each province. (2) Currently, the spatial association network structures of WUE and WCPE are sparse. However, with the government's basin-wide water conservation policy, the spatial relationships within the basin have gradually become more closely linked. The local clustering effect of WUE in space and the communication of technical elements in the WCPE stage in the basin are the main reasons for this network formation. Focusing on the WCPE stage, this study not only proposes policy suggestions to improve the efficiency of water resource intensification in the YRB by promoting the exchange of factors but can also be used as a reference for other basins with great regional differences. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of data record length on environmental flow calculation is presented. • Method 7Q10 is the less sensitive to environmental flow calculations. • Trend analysis should be the starting point for calculation of environmental flows. • Environmental flows have a significant impact on water resource availability. • Environmental flows are the starting point for sustainable water management. The paper presents the analysis of problems regarding the calculation of EFs using selected hydrological methods. It was conducted in 14 catchments in the Vistula and Oder River basins in Poland. The Kostrzewa, Tennant, Q 90% , and 7Q10 methods were used for the analysis. The analysis showed a significant trend in the hydrological time series. The sensitivity of different applied methods to time series length was shown. High differences were observed between environmental flow (EF) values calculated for periods defined by break points. The hydrological drought and its impact for EFs were also observed for half years in the period. Finally, different values of water deficit characteristics were presented depending on the method used for EF calculation. [ABSTRACT FROM AUTHOR]

Due to the discharge of pollutants, over-exploitation of water resources and large regional imbalances, it is critical to design an effective Reward and Penalty Mechanism (RPM) for the regions in a basin based on the Water Resource Environmental Carrying Capacity (WRECC) performance. To determine how to set the reference points of reward and penalty plans and design the RPM, the following approach is proposed. Firstly, since the evaluated regions always orient their activities towards certain goals at the initial stage of the evaluation period, this paper finds the closest goal for each indicator according to the previous performance using a DEA benchmarking model. Secondly, a reward and penalty plan addressing both reward and penalty within a unified benchmarking framework is designed according to the different alert levels determined from WRECC performances. Thirdly, an extended DEA model is developed to adjust the benchmarking of the current period to the goals to determine DEA targets that are achievable and represent best practices as reference points. The gaps between the DEA targets and actual observed values allow for us to identify the alert level of the evaluated region. The rewards or penalties of the current period can be obtained based on reward and penalty plans at the final stage. A case study concerning the WRECC-based PRM of the top 10 cities in China's Huaihe River basin is selected to demonstrate the validity of the proposed approach. The results indicate that the top 10 cities of the Huaihe River basin in 2016 are benchmarked against Zhengzhou, Yangzhou and Jining; Zhengzhou, Xuzhou, Yangzhou and Jining should receive rewards and the remainder of the evaluated cities should pay penalties. According to the results, the gap between the actual performance and the DEA targets can be defined; how much improvement the regions should make can be identified; and regions that should be rewarded or punished as well as the specific amount of money required can be determined. • Both reward and penalty plans are addressed within a unified benchmarking framework. • Not only the past performance but also the current situation are considered in the approach. • The proposed model is firstly applied to design an RPM based on the WRECC performance. [ABSTRACT FROM AUTHOR]

With the intensification of global warming and anthropogenic activities, warming or drying episodes with respect to water deficit has brought severe challenges across the globe. It becomes imperative to understand the drought characteristics as well as water resource availability in such regions. In this paper, we employ trend analysis to investigate the tendency of Potential Evapotranspiration (PET) and Climatic Water Balance (CWB) from 1979 to 2017 in the Jhelum river basin. We applied Thornthwaite parameterization which is based on latitude and monthly mean temperature for the computation of PET. The results showed that annual PET of Srinagar and Quazigund stations has increasing tendency while annual CWB has decreasing tendency for all the selected stations in the basin. The trend test applied to monthly PET and CWB indicate that monthly PET has increasing tendency in most of the months while monthly CWB has decreasing tendency in most of the months for all the selected stations in the basin. In addition to this, the drought events were characterized using Standardized Precipitation Evaporation Index (SPEI) based on 3, 6 and 12-month time scales. The SPEI was also applied to investigate the spatio-temporal characteristics of drought during the study period in the basin. The spatial patterns of drought severity were derived based on the Average Recurrence Interval (ARI). The temporal analysis revealed that an average of 65 long term, 69 intermediate term and 74 short term drought events were observed across the basin. However the spatial characteristics indicated that drought becomes more severe with long return periods in the western part of the basin. This study also investigated the influence of large scale climatic variables on 3 month SPEI over the basin using cross wavelet analysis. The results show that the drought characteristics are significantly influenced by both the ENSO and ENSO-M events throughout the Jhelum basin. [ABSTRACT FROM AUTHOR]

• Water withheld to maintain a certain level of reliability are a cost that are not evaluated in catchment wide studies. • Greater reliability is not always beneficial, as the value of water held to maintain a level of reliability is ignored. • Once considered on a system wide basis, the benefits of greater levels of reliability become circumspect. • Changing the level or reliability in an irrigation system will not affect all regions and parts of that system equally. Increasing water reliability in a catchment requires reducing the total quantity of water available to users in some years in order to supply it in more years when its supply is constrained. Thus, the more reliable the supply the more water that needs to be withheld. Consequently, increased levels of water reliability to a catchment, which reduces the costs associated with an unreliable supply, often comes at an incremental increase in costs that researchers do not consider; that of the water foregone that could be have been used productively if the system had been run less reliably. In this paper the trade-offs between the costs of water foregone to maintain a level of reliability and the costs associated with an unreliable supply of water at different levels of reliability in an irrigation system are discussed. The concepts developed are applied to the irrigation sector in the Musi catchment in Andhra Pradesh, India from 2011 to 2040. In this catchment it was found that the costs of water foregone to increase reliability rise as the level of reliability rises, while the benefits generally fall. When the level of reliability exceeded approximately 85% (where water is so scarce that it is used on only the most valuable output), the costs of greater reliability exceed the benefits resulting in net losses to the system. These results were found to vary in each demand centre across the catchment. These results have implications for those considering innovations that improve the level of reliability in a catchment. [ABSTRACT FROM AUTHOR]

• We used 1 × 1 km spatial and 1-hour temporal resolution hydro-meteorological data. • We used a parsimonious distance distribution dynamics (DDD) hydrological model. • We considered three different methods of regionalizations of the model parameters. • The three methods of regionalization perform satisfactorily. • This work contributes to water resource and flood management in small ungauged catchments. Streamflow data is important for studies of water resources and flood management, but an inherent problem is that many catchments of interest are ungauged. The lack of data is particularly the case for small catchments, where flow data with high temporal resolution is needed. This paper presents an analysis of regionalizing parameters of the Distance Distribution Dynamics (DDD) rainfall-runoff model for predicting hourly flows at small-ungauged rural catchments. The performance of the model with hourly time resolution has been evaluated (calibrated and validated) for 41 small gauged catchments in Norway (areas from 1 km2–50 km2). The model parameters needing regionalization have been regionalized using three different methods: multiple regression, physical similarity (single-donor and pooling-group based methods), and a combination of the two methods. Seven independent catchments, which are not used in the evaluation, are used for validation of the regionalization methods. All the three methods (the multiple regression, pooling-group, and combined methods) perform satisfactorily (0.5 ≤ KGE < 0.75). The combined method (which combines multiple regression and pooling-group) performed slightly better than the other methods. Some model parameters, namely those describing recession characteristics, estimated by the regionalization methods, appear to be a better choice than those estimated locally from short period of hydro-meteorological data for some test catchments. The single-donor method did not perform satisfactorily. The satisfactory performance of the combined method shows that regionalization of DDD model parameters is possible by combining multiple regression and physical similarity methods. [ABSTRACT FROM AUTHOR]

Abstract The estuarine delta of the Yellow River is a region of strong land-ocean-human interactions that undergoes a unique evolutionary process. In this paper, we combined historical data and remote sensing images to better understand the evolution of the Yellow River delta. Changes in the Yellow River estuarine flow path from natural swing to artificial diversion were first studied to understand the rules and mechanism of the delta formation. The complex geomorphic structural system of the Yellow River delta is constituted by contemporary and modern deltas and their sub-deltas. Remote sensing images and measured data indicate that variations in runoff and sediment load in the Yellow River estuary will affect the deltaic erosion and siltation. The natural and artificial factors that cause runoff and sediment changes include climate change, soil erosion control in the middle reaches, building reservoirs along the Yellow River, which are used as water supply for local cities and farmland irrigation, as well as the water and sediment regulation experiment in the Xiaolangdi reservoir. Furthermore, artificial intervention of diversion channels has contributed to the maintained stability of the Yellow River estuary environment, so as to have regional development and prosperity of the Yellow River delta. Graphical abstract Image 1 Highlights • The Yellow River estuarine flow paths change from natural swing to artificial diversion, and the delta formation rule. • The variation of runoff and sediment load in the Yellow River affect the deltaic erosion and siltation. • Probe into the natural and artificial reasons of runoff and sediment changes and decrease. • The estuarine artificial control maintains relative stableenvironment and creates prosperity of the Yellow River delta. • This study reflects land-ocean-human interaction on estuarine coastal region. [ABSTRACT FROM AUTHOR]

Abstract A river basin usually provides water for multiagent. Imperfect coordination mechanisms among these agents, however, usually lead to serious water shortage, pollution, and ecological degradation. Therefore, it is vital to conduct research on allocating different kinds of water resources among multiagent including the water quantity agent, water quality agent and environment agent within a river basin. This paper proposes an optimization-simulation method that takes into consideration engineering measures, including water transfer projects, reservoirs, canal heads, and pump stations; multi-water resources such as local surface water, transferred water, groundwater, and reused sewage; and multiagent for remitting serious water problems. In the proposed optimization-simulation method, the groundwater and reused sewage are first allocated according to the water resources allocation simulation module (Module 1). Then, local surface and transferred water are allocated based on the water resources allocation optimization module (Module 2), which comprises water quantity, water quality and environment agents' objectives based on synergism. Finally, the instream water quality is simulated according to the water quality simulation module (Module 3). Results show that, compared to the current situation, the water quantity and environment agent guarantee rates can satisfy the design requirements in the planning year of 2020. The regulated instream water quality is also improved; although, it still remains relatively poor. Water quality in the downstream is worse than that in the upstream. In addition, the water quality shows a positive correlation with the instream streamflow. These results certify the proposed optimization-simulation method can provide support for efficacious multiagent water resources allocation. Highlights • A coupled quantity-quality-environment water allocation model is constructed. • Multi-water resources, many types of engineering projects and multiagent are considered. • Multi-water resources cover local surface, transferred water, groundwater, and reused sewage. • Water transfer projects, reservoirs, canal heads, and pump stations are selected projects. • Coupled model is solved by an optimization-simulation method. [ABSTRACT FROM AUTHOR]

Highlights • Discharge measurements are exposed to different levels of uncertainties. • Impacts of land use change could be masked by errors in discharge measurements. • 50−75% of errors in discharge measurement can mask impact of land use change. • Data quality controls will enhance precision of land use change impact. Abstract Analysis of hydrological impacts of land use change raises questions about whether, and how much, such impacts are misrepresented because of errors in river flow observations. In this paper, land use change impacts (represented by changes in watershed storage) and different ranges of discharge measurement error are compared to assess how errors in discharge measurement can potentially mask a land use change impact. Using a watershed from the Ethiopian highlands to exemplify this, we simulated five different levels of land use change impacts with five levels of watershed storage reductions (from 10% to 50% change) and the associated time series of runoff. Different levels of observation error were then introduced into these artificial time series. Comparison was made between every pair, i.e. a time series derived from a certain level of land use change (storage reduction) versus a time series corresponding to a given level of observation error, using a step-change t -test. Significant step-changes between pairs define the detectability of land use change impact. The analysis was made for the entire 30-year time series as well as for the most extreme annual weather conditions. The results showed that for the average year and wettest year, 75% or more error in observed discharge masks the maximum simulated land use change impact on hydrology. In dry years, a 50% error in discharge is enough to mask the same impact. Knowing (and improving) the level of data quality contributes to a better understanding of hydrological uncertainties and improves the precision in assessing land use change impacts. Both of these are essential elements in water resources development planning. [ABSTRACT FROM AUTHOR]

• A method was proposed by coupling the ERI and the CLUE-S model. • Three different scenarios designed to explore ERI of LUCC in 2027. • Spatiotemporal characteristics of ERI were predicted under different scenarios. The Jinghe County of the Ebinur Lake Basin was chosen as the study area. Based on Landsat TM / OLI images obtained in 2007 and 2017, this paper attempts to use CLUE-S model to predict LUCC under three different scenarios (Natural Development scenario, Farmland Protection scenario, Water Resources Protection scenarios) in 2027. Landscape indices and ecological risk index were calculated and spatially interpolated for the whole region, and the results of ecological risk could be divided into five different zones: extremely low, low, moderate, high and extremely high. They were carried out for assessing the spatial–temporal changes in ecological risk for each landscape pattern. The results show that: (1) Among the three scenarios designed in this paper, the spatial distribution of LUCC in the Water Resource Protection scenario has the most obvious changes, followed by the Farmland Protection scenario and the Natural Development scenario becomes the third. In the water resources protection scenario, the scale of the desert decreases, but the forest and grass part increases, which is conducive to ecological improvement. (2) the distribution area of high ecological risk areas was the largest of three different scenarios, especially the farmland protection scenario. The area of low-risk level is the largest under the water conservation scenario. The ecological risk of LUCC under the water resources protection scenario is lower, which is better for ecological environment. (3) Water bodies mainly concentrate upon low ecological risk degree, accounting for approximately 62.8%, 82.2%, and 73.1% of low ecological risk; Farmland mainly lies in the low-risk areas, accounting for 59.1%, 63.5% and 68.8% of the lower ecological risk levels; In 2027, the unused land and other land types are the main land types of the higher ecological risk areas under three different scenarios, whose proportions are 67.40%, 68.24% and 65.90%, respectively. [ABSTRACT FROM AUTHOR]

• Water resources carrying capacity(WRCC) as the ability of the area to carry pressures from the economy, society, and ecology within a sustainable development of water resources. • Construct a four-sided evaluation index system including 21 indicators. • entropy method and CRITIC method are applied. • Game theory is cited in combinatorial empowerment. • The mean value of the WRCC index of the Tarim River basin in Xinjiang is 0.34. • The WRCC of the Tarim River basin in Xinjiang shows a trend of horizontal fluctuation and then a steady increase. As a basic resource, water resources are the controlling element of ecological environment construction and are vital to social development and human survival. Water resources carrying capacity is an important criterion to measure the harmony of ecology, society, economy and resources in the region. The increasing contradiction of water resources in the Tarim River Basin of Xinjiang has restricted the rigid constraints of water resources in various fields of economic and social development. In order to provide a better basis for water resources management in the Tarim River Basin. This paper selects 21 indicators and constructs an evaluation system containing four subsystems: water resources, society, economy, and ecology. The objective function is constructed through the idea of game assembly, and the comprehensive weights obtained by combining the entropy weighting method and CRITIC method are assigned. Finally, we substitute into TOPSIS model to calculate the proximity to get the water resources carrying capacity index. The results show that the average value of the water resources carrying capacity index of the five prefectures of the Tarim River Basin in Xinjiang from 2010 to 2019 is 0.34, and according to the trend of change with the year, the carrying capacity of the five prefectures fluctuates at a low level from 2011 to 2016. Except for Bazhou, where the water resources carrying capacity dropped sharply due to the transfer of water to the outside, the other four prefectures showed an overall upward trend after 2016. This indicates that the water resources carrying capacity of the Tarim River basin, which was on the verge of overload in the past, is gradually becoming better after the rectification of relevant measures such as counterpart assistance to Xinjiang and efficient water conservation. And there is still more room for development in the future. [ABSTRACT FROM AUTHOR]

Floods are one of the deadliest natural hazards and are exacerbated by changes in land-use and climate. Urban development decreases infiltration by reducing pervious areas and increases the accumulation of pollutants during dry weather. It also decreases infiltration by reducing pervious areas and increases the accumulation of pollutants during dry periods. During rainy events, there is an increase in pollution concentrations and runoff that may be a source of water supply during drought periods. Modeling the quantity and quality dynamics of stormwater runoff requires a coupled hydrodynamic module capable of estimating the transport and fate of pollutants. In this paper, we evaluate the applicability of a distributed hydrodynamic model coupled with a water quality model (HydroPol2D). First, the model is compared to GSSHA and WCA2D in the V-Tilted catchment, and the limitation of the critical velocity of WCA2D is investigated. We also applied the model in a laboratory wooden board catchment, focusing on the validation of the numerical approach to simulate water quality dynamics. Then, we apply HydroPol2D in the Tijuco Preto catchment, in São Carlos - Brazil, and compare the modeled results with the full momentum solver of the HEC-RAS 2D. This catchment shares similar characteristics with many poorly-gauged and human-impacted catchments worldwide. The implementation of the model, the governing equations, and the estimation of input data are discussed, indicating the challenges and opportunities to scale HydroPol2D into the reality of data scarcity of larger poorly-gauged catchments. For a 1-yr return period of rainfall and antecedent dry days, and assuming an uncertainty of 40% in the water quality parameters, the results indicate that the maximum concentration of total suspended solids (TSS), the maximum load and the mass of the pollutant washed in 30% of the volume are, 456 ± 260 mgL-1km-2, 2. 56 ± 0. 4 kgs-1km-2, and 89 % ± 10 % , respectively. [Display omitted] • A new coupled hydrodynamic and water quality 2D model is developed (HydroPol2D). • The spatial–temporal dynamics of Total Suspended Solids (TSS) is investigated. • We estimate TSS transport rates and first flush for a 1-year return period. • The maximum TSS load is 2. 56 ± 0. 4 kg s − 1 km − 2 for a 40% uncertainty in water quality parameters. • HydroPol2D can also be used for flood inundation mapping, infiltration, and evapotranspiration modeling. [ABSTRACT FROM AUTHOR]

An emergent strategy to target sustainability involves an understanding of the water-energy interconnections. It takes water to produce energy, and it takes energy to source, treat, and distribute water. Sanitation and energy distribution are the world's pre-eminent development challenges. They are a magnifier of poverty, ill-health and mortality, and gender inequality. The word 'nexus' means the understanding of these interdependencies, tensions, and trade-offs. This paper investigates water-energy interconnections through critical analysis. We applied a bottom-up approach to describe Sao Paulo state's river basins, in Southeast Brazil, from the household to the regional scale. Initially, water availability, energy consumption and wastewater treatment data are inferred using per capita data. The subsequent data analysis then considered the positive and negative linkages among the basins. Local and state levels of dependency are also assessed, considering environmental and socioeconomic impacts. The significance of this paper lies in understanding these interconnections and their interdependence within the local context and individuals' behaviour. The results allow a comprehensive analysis of the water-energy Nexus across Sao Paulo state. The critical analysis also shows how the primary drivers contribute to urbanisation levels, population growth, and industrial activities. • Regional WE Nexus analysis is undertaken for the most industrialised state of Brazil. • The increase in wastewater treatment highlights the sustainability path. • Wastewater treatment growth rates are higher than population and GDP rates. • It develops a unique database for future studies using the Nexus approach. • Population growth, GDP, and industrial intensity are the main drivers in the WE Nexus. [ABSTRACT FROM AUTHOR]

Climate change and human activities have changed the spatial-temporal distribution of water resources, especially in a fragile ecological area such as the upper reaches of the Minjiang River (UMR) basin, where they have had a more profound effect. The average of double-mass curve (DMC) and Distributed Time-Variant Gain Hydrological Model (DTVGM) are applied to distinguish between the impacts of climate change and human activities on water resources in this paper. Results indicated that water resources decreased over nearly 50 years in the UMR. At the annual scale, contributions of human activities and climate change to changes in discharge were −77% and 23%, respectively. In general, human activities decreased the availability of water resources, whereas climate change increased the availability of water resources. However, the impacts of human activities and climate change on water resources availability were distinctly different on annual versus seasonal scales, and they showed more inconsistency in summer and autumn. The main causes of decreasing water resources are reservoir regulation, and water use increases due to population growth. The results of this study can provide support for water resource management and sustainable development in the UMR basin. [ABSTRACT FROM AUTHOR]

China's “Developing a Water-saving Society” policy is an ambitious water conservation strategy. However, there has been little evidence of the policy's effectiveness in terms of saving water at a river basin level. In this paper, we used a basin-scale hydroeconomic input-output model to calculate the water consumption ( WC ) by producers and consumers ( WC p and WC c ), respectively in the first pilot area for implementation of this policy, the Heihe River Basin, which belongs to an arid area in inland China. The results show that, after implementation of the policy, WC c decreased sharply but WC p only decreased slightly. A structural decomposition analysis revealed that decreased water consumption intensity played an important role in reducing water consumption. However, this effect was largely offset by the increasing exports of virtual water in goods and services. Our results suggest that in arid river basins, measures in saving water must be accompanied with a cap on total water consumption which is set in accordance with the local water endowments and consideration of environmental water requirement. [ABSTRACT FROM AUTHOR]

Degradation of freshwater ecosystems and the services they provide is a primary cause of increasing water insecurity, raising the need for integrated solutions to freshwater management. While methods for characterizing the multi-faceted challenges of managing freshwater ecosystems abound, they tend to emphasize either social or ecological dimensions and fall short of being truly integrative. This paper suggests that management for sustainability of freshwater systems needs to consider the linkages between human water uses, freshwater ecosystems and governance. We present a conceptualization of freshwater resources as part of an integrated social-ecological system and propose a set of corresponding indicators to monitor freshwater ecosystem health and to highlight priorities for management. We demonstrate an application of this new framework —the Freshwater Health Index (FHI) — in the Dongjiang River Basin in southern China, where stakeholders are addressing multiple and conflicting freshwater demands. By combining empirical and modeled datasets with surveys to gauge stakeholders' preferences and elicit expert information about governance mechanisms, the FHI helps stakeholders understand the status of freshwater ecosystems in their basin, how ecosystems are being manipulated to enhance or decrease water-related services, and how well the existing water resource management regime is equipped to govern these dynamics over time. This framework helps to operationalize a truly integrated approach to water resource management by recognizing the interplay between governance, stakeholders, freshwater ecosystems and the services they provide. [ABSTRACT FROM AUTHOR]

River discharge is a critical water cycle variable, as it integrates all the processes (e.g. runoff and evapotranspiration) occurring within a river basin and provides a hydrological output variable that can be readily measured. Its prediction is of invaluable help for many water-related tasks including water resources assessment and management, flood protection, and disaster mitigation. Observations of river discharge are important to calibrate and validate hydrological or coupled land, atmosphere and ocean models. This requires using datasets from different scientific domains (Water, Weather, etc.). Typically, such datasets are provided using different technological solutions. This complicates the integration of new hydrological data sources into application systems. Therefore, a considerable effort is often spent on data access issues instead of the actual scientific question. This paper describes the work performed to address multidisciplinary interoperability challenges related to river discharge modeling and validation. This includes definition and standardization of domain specific interoperability standards for hydrological data sharing and their support in global frameworks such as the Global Earth Observation System of Systems (GEOSS). The research was developed in the context of the EU FP7-funded project GEOWOW (GEOSS Interoperability for Weather, Ocean and Water), which implemented a “River Discharge” application scenario. This scenario demonstrates the combination of river discharge observations data from the Global Runoff Data Centre (GRDC) database and model outputs produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) predicting river discharge based on weather forecast information in the context of the GEOSS. [ABSTRACT FROM AUTHOR]

One of the significant economic benefits to communities around the world of having pristine forest catchments is the supply of substantial quantities of high quality potable water. This supports a saving of around US$ 4.1 trillion per year globally by limiting the cost of expensive drinking water treatments and provision of unnecessary infrastructure. Even low levels of contaminants specifically organics and metals in catchments when in a mobile state can reduce these economic benefits by seriously affecting the water quality. Contamination and contaminant mobility can occur through natural and anthropogenic activities including forest fires. Moderate to high intensity forest fires are able to alter soil properties and release sequestered metals from sediments, soil organic matter and fragments of vegetation. In addition, the increase in post-fire erosion rate by rainfall runoff and strong winds facilitates the rapid transport of these metals downslope and downstream. The subsequent metal deposition in distal soil and water bodies can influence surface water quality with potential impacts to the larger ecosystems inclusive of negative effects on humans. This is of substantial concern as 4 billion hectares of forest catchments provide high quality water to global communities. Redressing this problem requires quantification of the potential effects on water resources and instituting rigorous fire and environmental management plans to mitigate deleterious effects on catchment areas. This paper is a review of the current state of the art literature dealing with the risk of post-fire mobilization of the metals into surface water resources. It is intended to inform discussion on the preparation of suitable management plans and policies during and after fire events in order to maintain potable water quality in a cost-effective manner. In these times of climate fluctuation and increased incidence of fires, the need for development of new policies and management frameworks are of heighted significance. [ABSTRACT FROM AUTHOR]

Climate change, population growth, and weakly developed water management institutions in many of the world’s dry communities have raised the importance of designing innovative water allocation methods that adapt to water supply fluctuations while respecting cultural sensitivities. For example, Afghanistan faces an ancient history of water supply fluctuations that have contributed to periodic food shortage and famine. Poorly designed and weakly enforced water allocation methods continue to result in agriculture sector underperformance and periodic food shortages when water shortfalls occur. To date, little research has examined alternative water sharing rules on a multi-basin scale to protect food security for a subsistence irrigation society when the community faces water shortage. This paper’s contribution examines the economic performance of three water-sharing mechanisms for three basins in Afghanistan with the goal of protecting food security for crop irrigation under ongoing threats of drought, while meeting growing demands for food in the face of anticipated population growth. We achieved this by formulating an integrated empirical optimization model to identify water-sharing measures that minimize economic losses while protecting food security when water shortages occur. Findings show that implementation of either a water trading policy or a proportional shortage policy that respects cultural sensitivities has the potential to raise economic welfare in each basin. Such a policy can reduce food insecurity risks for all trading provinces within each basin, thus being a productive institution for adapting to water shortage when it occurs. Total economic welfare gains are highest when drought is the most severe for which suffering would otherwise be greatest. Gains would be considerably higher if water storage reservoirs were built to store wet year flows for use in dry years. Our results light a path for policy makers, donors, water administrators, and farm managers, who shoulder the burden of protecting food security and rural livelihoods in the world’s poor dry communities. [ABSTRACT FROM AUTHOR]

In semi-arid catchments, hydrological modeling, water resources planning and management are hampered by insufficient spatial rainfall data which is usually derived from limited rain gauge networks. Satellite products are potential candidates to augment the limited spatial rainfall data in these areas. In this paper, the utility of the Tropical Rainfall Measuring Mission (TRMM) product (3B42 v7) is evaluated using data from the Notwane catchment in Botswana. In addition, rainfall simulations obtained from a multi-site stochastic rainfall model based on the generalised linear models (GLMs) were used as additional spatial rainfall estimates. These rainfall products were compared to the observed rainfall data obtained from six (6) rainfall stations available in the catchment for the period 1998–2012. The results show that in general the two approaches produce reasonable spatial rainfall estimates. However, the TRMM products provided better spatial rainfall estimates compared to the GLM rainfall outputs on an average, as more than 90% of the monthly rainfall variations were explained by the TRMM compared to 80% from the GLMs. However, there is still uncertainty associated mainly with limited rainfall stations, and the inability of the two products to capture unusually high rainfall values in the data sets. Despite this observation, rainfall indices computed to further assess the daily rainfall products (i.e. rainfall occurrence and amounts, length of dry spells) were adequately represented by the TRMM data compared to the GLMs. Performance from the GLMs is expected to improve with addition of further rainfall predictors. A combination of these rainfall products allows for reasonable spatial rainfall estimates and temporal (short term future) rainfall simulations from the TRMM and GLMs, respectively. The results have significant implications on water resources planning and management in the catchment which has, for the past three years, been experiencing prolonged droughts as shown by the drying of Gaborone dam (currently at a record low of 1.6% full), which is the main source of water supply to the city of Gaborone and neighbouring townships in Botswana. [ABSTRACT FROM AUTHOR]

• The present situation is analyzed by using spatial autocorrelation and spatiotemporal feature distribution. • The entropy weight method and analytic hierarchy process are combined to calculate the weight of each index. • The coupling coordination degree evaluation model of WEF system in the Yellow River basin of Shandong province is established. • The coupling coordination degree of the Yellow River basin in Shandong province is about to reach a good coupling stage. • The PSO-BP model has good applicability in coupling coordination degree prediction. Water resources, energy, and food are important basic resources for high-quality regional development. In the process of rapid development of regional economy, how to coordinate the development of basic resources has become one of the most serious challenges to the high-quality development of the Yellow River basin and even the whole Yellow River basin in Shandong province. Previous studies have produced few such analyses and evaluations for cities in the Yellow River basin, and there is a lack of research on multi-scale analysis, evaluation and prediction of urban coupling and coordinated development level. Hence, in this study, we propose an indicator system consisting of 24 indicators for the water resources, energy, and food system based on panel data for 9 cities in the Yellow River basin in Shandong Province for 2011–2020. Spatial autocorrelation analysis and temporal and spatial distribution analysis were used to determine the current state of water resources, energy, and food systems at multiple scales; combined weighting, comprehensive evaluation, and coupling coordination quantification were used to formulate the coupling coordination relationships of water resources–energy–food and identify the spatiotemporal formation and development of the water resources–energy–food system. A particle swarm optimization–back propagation model (PSO-BP) was used to predict the coupled and coordinated changes in the water resources–energy–food system for the next five years. The study results show that: (1) The composite index of the water resources–energy–food system showed an increasing trend, and the composite index of the food subsystem increased relatively quickly. (2) In 2020, the coupling coordination degree for eight of the nine cities in the Yellow River basin in Shandong Province was 0.70. Jinan, the exception, was at a critical stage of transitioning from low to moderate coupling, and the other eight cities were at the moderate stage of coupling coordination. (3) The coupling coordination of the water resources–energy–food system is increasing; it has transitioned from low to moderate and is about to transition to the stage of good coupling coordination. (4) The PSO-BP model predicted that the coupling coordination of water resources–energy–food systems in the Yellow River basin in Shandong Province will reach the stage of good coupling coordination in 2023. The research results presented in this paper can provide a theoretical basis for formulating policy recommendations in the Yellow River basin in Shandong Province. [ABSTRACT FROM AUTHOR]

Water resources is one of the basic resources for human social development. In the context of China's rapid economic development, how to achieve the sustainable development of water resources, social economy and ecological environment has become an urgent issue. Water Resources Carrying Capacity (WRCC) is an important indicator of the degree of coordinated social, economic and ecological development that can be supported by water resources in a certain region. Based on the internal mechanism of WRCC, this paper constructs the evaluation system of WRCC, and estimates WRCC of 9 provinces in the Yellow River Basin (YRB) from 2009 to 2018 by the entropy method. Using the Logarithmic Mean Divisia Index (LMDI) model, we analyze the driving effects of WRCC differences in the YRB from both spatial and temporal aspects. Main conclusions are as follows: (1) There is an inherent mechanism between water resources, social economy and eco-environment, and the coordinated development of the three subsystems can promote the improvement of WRCC; (2) From 2009 to 2018, WRCC of the YRB showed a relatively stable upward trend, in which the sewage treatment effect and the technical effect were the main factors promoting WRCC, while the economic effect had a negative weakening function throughout the research period; (3) There were obvious differences in the WRCC of each province. We choose Shandong and Gansu as the comparison objects, then analyze the factors causing differences of WRCC through the driving effects decomposition analysis. [ABSTRACT FROM AUTHOR]

• BMA improved estimation of prediction uncertainty for daily streamflow simulations. • Applying BMA provided a better understanding of SWAT-HS reliability and precision. • BMA models had similar estimations for model reliability, but different for precision. • BMA showed that MNSE had the highest predictive ability in simulating streamflow. In this paper, multiple objective functions were used to conduct uncertainty analysis on calibrated streamflow simulations of SWAT-hillslope model (SWAT-HS), which is a semi-distributed model suited for humid, mountainous regions. SWAT-HS was set up for six watersheds of NYC water supply system and streamflow was simulated at a daily time step. Each SWAT-HS model setup was then passed through a calibration process for parameter optimization. This process involved constraining the model using several alternative objective functions which produce statistically acceptable streamflow simulations, which served as an ensemble of predictions for uncertainty analysis. We hypothesize that the uncertainty introduced by selecting a single objective function can be large with each objective function being sensitive to a specific hydrologic signature. Using multiple objective functions result in a wider range in optimum parameter values and an ensemble of simulations based on different objective functions can capture the overall prediction uncertainty through differences in parameter estimates. The Bayesian Model Averaging (BMA) method was then applied to ensemble predictions to quantify overall prediction uncertainty. The uncertainty analysis showed the similarity of uncertainty interval characteristics for all BMA based predictions across all watersheds. More than 94–97% of the observations were covered by uncertainty intervals estimated using multiple objective functions when compared to 73–79% of the observations when using a single objective function. No significant differences were observed among the six watersheds, and the results of their uncertainty analysis were similar. We propose the use of multiple objective functions as an option in ensemble modeling of streamflow and uncertainty analysis. [ABSTRACT FROM AUTHOR]

The Water Framework Directive (WFD) 2000/60/EC clearly indicates that all member states should develop and apply water pricing policies to recover the Full Water Cost (FWC) (including the direct cost, the environmental and the water resource costs). Drinking water pricing policies set by the water utilities today do not comply with the WFD basic principle. They are rather determined locally, without taking into consideration environmental (e.g. river basin water balance) or economic issues (e.g. socially fair allocation of the water cost). This paper proposes a new, socially fair drinking water pricing policy, taking into consideration the FWC recovery and socially fairness. This methodology is applied in the water utility of Kozani, in Greece. [ABSTRACT FROM AUTHOR]

River basin planning and management constitute complex decision problems, characterized by many actors and stakeholders with conflicting objectives and values, ranging from the protection of local flora and fauna and the enhancement of the recreational value of the river, to the preservation of the water resources for industrial purposes and human activities. In the light of the aforementioned complexity, specific evaluation methods are needed for supporting decision-making processes in this context. The present paper proposes an evaluation approach based on the combined use of two different evaluation techniques, the Spatial Multicriteria Evaluation and the stakeholders analysis, for supporting the definition of policies and actions for a river basin. In particular, alternative predictive scenarios are generated through the Ordered Weighted Average method in order to explore different solutions. Starting from the Pellice river basin (Italy), the study presents the results of the integrated evaluation approach, focusing on the potentialities of the methodology for supporting the definition of future policies and plans for the area. [ABSTRACT FROM AUTHOR]

A large part of the Sahel consists of endorheic hydrological systems, where reservoirs and lakes capture surface runoff during the rainy season, making water available during the dry season. Monitoring and understanding the dynamics of these lakes and their relationships to the ecohydrological evolution of the region is important to assess past, present and future changes of water resources in the Sahel. Yet, most of Sahelian watersheds are still ungauged or poorly gauged, which hinders the assessment of the water flows feeding the lakes and the overall runoff over their watershed. In this paper, a methodology is developed to estimate water inflow to lakes for ungauged watersheds. It is tested for the Agoufou lake in the Gourma region in Mali, for which in situ water height measurements and surface areas estimations by remote sensing are simultaneously available. A Height-Volume-Area (HVA) model is developed to relate water volume to water height and lake surface area. This model is combined to daily evaporation and precipitation to estimate water inflow to the lake, which approximates runoff over the whole watershed. The ratio between annual water inflow and precipitation increases over the last sixty years as a result of a significant increase in runoff coefficient over the Agoufou watershed. The method is then extended to derive water inflow to three other Sahelian lakes in Mauritania and Niger. No in situ measurements are available and lake surface areas estimation by remote sensing is the only source of information. Dry season surface area changes and estimated evaporation are used to select a suited VA relationship for each case. It is found that the ratio between annual water inflow and precipitation has also increased in the last 60 years over these watersheds, although trends at the Mauritanian site are not statistically significant. The remote sensing approach developed in this study can be easily applied to recent sensors such as Sentinel-2 or Landsat-8, to quantify the evolution of hydrological systems in ungauged Sahelian regions. [ABSTRACT FROM AUTHOR]

Likangala River catchment in Zomba District of Southern Malawi is important for water resources, agriculture and provides many ecosystem services. Provisioning ecosystem services accrued by the populations within the catchment include water, fish, medicinal plants and timber among others. In spite of its importance, the River catchment is under threat from anthropogenic activities and land use change. This paper studies land uses and land cover change in the catchment and how the changes have impacted on the ecosystem services. Landsat 5 and 8 images (1984, 1994, 2005 and 2013) were used to map land cover change and subsequent inventorying of provisioning ecosystem services. Participatory Geographic Information Systems and Focus group discussions were conducted to identify provisioning ecosystems services that communities benefit from the catchment and indicate these on the map. Post classification comparisons indicate that since 1984, there has been a decline in woodlands from 135.3 km 2 in 1984 to 15.5 km 2 in 2013 while urban areas increased from 9.8 km 2 to 23.8 km 2 in 2013. Communities indicated that provisioning ecosystems services such as forest products, wild animals and fruits and medicinal plants have been declining over the years. In addition, evidence of catchment degradation through waste disposal, illegal sand mining, deforestation and farming on marginal lands were observed. Population growth, urbanization and demand for agricultural lands have contributed to this land use and land cover change. The study suggests addressing catchment degradation through integrated method where an ecosystems approach is used. Thus, both the proximate and underlying driving factors of land-use and land cover change need to be addressed in order to sustainably reduce ecosystem degradation. [ABSTRACT FROM AUTHOR]

Summary Much has been written on the hydrology of the Yangtze River in China, especially since the construction of the Three Gorges Dam. Given the range of views in the literature on the impacts of dams and other natural and anthropogenic activities in the catchment on monthly flows, we here set out to analyse the behavior of monthly flows over the period of record 1955–2014. In the literature, the Three Gorges dam has been singled out for particular comment, mostly adverse. In this paper we analyse trend in temperature, precipitation and discharge of the Yangtze River at the monthly time scale over a period that includes the 11 years since the Three Gorges Dam came into operation. The results show that for the upper basin, there has been a marked increase in discharge in the low flow months of January to March that began abruptly in 2003 and an abrupt decrease in flow in October at the same time. Similar changes are found for discharge from the lower basin but in that case the changes have occurred gradually over the period of record. These changes are the outcome of the operation of hydroelectric and flood control dams that have been built continuously in the lower basin since 1955 while in the upper basin the building of the Three Gorges Dam began a phase of rapid dam building not seen in the lower basin. The decreased flows in the late summer and autumn are not of sufficient magnitude to cause any problems for navigation or water supply. The enhanced flows in the winter low flow period are beneficial in that they reduce the likelihood of salt water intrusions in the estuary adversely affecting the supply of freshwater to Shanghai. [ABSTRACT FROM AUTHOR]

A portfolio of water management strategies now exists to contribute to reach water demand and supply targets. Among them, integrated water resource management has a large potential for reducing water disagreement in water scarcity regions. Many of the strategies are based on well tested choices and technical know-how, with proven benefits for users and environment. This paper considers water management practices that may contribute to reduce disagreement in water scarcity areas, evaluating the management alternatives in the Mediterranean basins of Europe, a region that exemplifies other water scarcity regions in the world. First, we use a model to compute water availability taking into account water management, temporal heterogeneity, spatial heterogeneity and policy options, and then apply this model across 396 river basins. Second, we use a wedge approach to illustrate policy choices for selected river basins: Thrace (Greece), Guadalquivir, Ebro, Tagus and Duero (Spain), Po (Italy) and Rhone (France). At the wide geographical level, the results show the multi-determinant complexities of climate change impacts and adaptation measures and the geographic nature of water resources and vulnerability metrics. At the local level, the results show that optimisation of water management is the dominating strategy for defining adaptation pathways. Results also show great sensitivity to ecological flow provision, suggesting that better attention should be paid to defining methods to estimate minimum ecological flows in water scarcity regions. For all scales, average water resource vulnerability computed by traditional vulnerability indicators may not be the most appropriate measure to inform climate change adaptation policy. This has large implications to applied water resource studies aiming to derive policy choices, and it is especially interesting in basins facing water scarcity. Our research aims to contribute to shape realistic water management options at the regional level and therefore provide information to climate change, agricultural and water policies. [ABSTRACT FROM AUTHOR]