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Small agricultural reservoirs support water demands during dry spells. However, evaporative losses that are often overlooked in water accounting and management diminish the storage efficiency of these popular but un‐inventoried resources. We developed a predictive framework to identify the spatio‐temporal extent of small reservoirs (900–100,000 m2) and quantify their evaporative losses using a physically‐based model. Focusing on water‐stressed regions of Europe (Italy, Spain, and Portugal), our results indicate that the total number and cumulative area of small reservoirs in drier areas of Europe almost doubled in two decades from about 6,200 reservoirs with the cumulative area of 46 km2 in 2,000 to 11,800 reservoirs with the cumulative area of 93.5 km2 in 2020. We observed climate‐driven trends in the expansion of agricultural reservoirs and their evaporative losses which exceeded 72 million cubic meters during warm months (April to September) accounting for 38% of their total storage capacity. Plain Language Summary: Small agricultural reservoirs play a key role in supporting irrigation and local demands in a warming climate. However, evaporation diminishes their storage efficiency. We provide a physically‐based framework for estimating global abundance and evaporative losses from small reservoirs serving as a basis for improving water management and planning. To show the applicability of the proposed method, we focused on water‐stressed regions of Europe (Italy, Spain, and Portugal). We found that cumulative area of small reservoirs in the study area has reached to 93.5 km2 in 2020 with cumulative evaporative losses that may exceed 72 million cubic meters. The study offers new insights into the improved understanding of the role and efficiency of small water storage infrastructure in water planning strategies. Key Points: A physically‐based framework was proposed to identify the extent of small reservoirs (<0.1 km2) and quantify their evaporative lossesTotal number and cumulative area of small agricultural reservoirs in water‐stressed regions of southern Europe doubled in two decadesStrong correlations were found between expansion of agricultural reservoirs, air temperature and precipitation [ABSTRACT FROM AUTHOR]

Although the UN concluded, already in 1997, that water would be the most contentious issue of the 21st century, water governance is still confused, nearly everywhere. Even the severe impacts of escalating water bankruptcy and global warming have so far failed to incur a marked improvement in governance systems. The global community has adopted sustainable development as a common vision and guide for the future. Yet, the adoption of the underlying principles of sustainable development has been slow in the water sector and elsewhere. Despite the realization that water governance is a political issue, the near-universal neoliberal agenda tends to only employ technologic and economic solutions to address water problems. This paper presents a historical overview, from the end of the Second World War (WWII) and onwards, of events that could, or should, have had an impact on water management frameworks. It evidences some important consequences of the institutional rigidity exposed during that period. The paper also turns to the fields of science, policy, and management, to pinpoint failures in the translation of political rhetoric as well as new scientific findings into change at the operational level. It explores how an updated knowledge base could serve a quest for sustainable water governance strategies. It is argued that a persistent failure to learn is an important reason behind the dire state that we are now in. As a result, water management is still based on century-old, technocratic, and instrumental methodologies that fail to take advantage of important scientific advancements since WWII and remain unable to properly deal with real-world complexities and uncertainties. The paper concludes that when it is linked to a transformation of the institutional superstructure, adaptive water management (AWM), a framework rooted in systems thinking, emerges as a prominent way to embark on a needed, radical transformation of the water governance systems. [ABSTRACT FROM AUTHOR]

The Zayandeh-Rud River Basin in the central plateau of Iran continues to grapple with water shortages due to a water-intensive development path made possible by a primarily supply-oriented water management approach to battle the water limits to growth. Despite inter-basin water transfers and increasing groundwater supply, recurring water shortages and associated tensions among stakeholders underscore key weaknesses in the current water management paradigm. There was an alarming trend of groundwater depletion in the basin's four main aquifers in the 1993–2016 period as indicated by the results of the Mann-Kendall3 (MK3) test and Innovative Trend Analysis (ITA) of groundwater volume. The basin's water resources declined by more than 6 BCM in 2016 compared to 2005 based on the equivalent water height (EWH) derived from monthly data (2002–2016) from the GRACE. The extensive groundwater depletion is an unequivocal evidence of reduced water availability in the face of growing basin-wide demand, necessitating water saving in all water use sectors. Implementing an integrated water resources management plan that accounts for evolving water supply priorities, growing demand and scarcity, and institutional changes is an urgent step to alleviate the growing tensions and preempt future water insecurity problems that are bound to occur if demand management approaches are delayed. [ABSTRACT FROM AUTHOR]

Problems have a high rank in decision making when they are both urgent and important. Accordingly, water has not earned the attention it deserves in public policy agenda because under normal circumstances it is not viewed as an urgent matter in the eyes of the public and politicians. By creating a sense of urgency, extreme events such as droughts, floods, conflicts, and migrations can create opportunities for implementing some essential policy reforms that would be politically costly otherwise. So, despite their high short-term costs, extreme natural and societal events have the potential to increase the resilience of water systems in the long run. It is argued here that the societal and political sense of urgency about water must be promoted through public outreach and information dissemination. Otherwise, for useful reforms and long-term improvements, we will rely on costly and risky extreme events that sometimes have the potential to fully collapse the human-natural system-of-systems. [ABSTRACT FROM AUTHOR]

Lake Urmia, one of the largest saltwater lakes on earth and a highly endangered ecosystem, is on the brink of a major environmental disaster similar to the catastrophic death of the Aral Sea. With a new composite of multi-spectral high resolution satellite observations, we show that the area of this Iranian lake has decreased by around 88% in the past decades, far more than previously reported (-25% to 50%). The lake's shoreline has been receding severely with no sign of recovery, which has been partly blamed on prolonged droughts. We use the lake basin's satellite-based gauge-adjusted climate record of the Standardized Precipitation Index data to demonstrate that the on-going shoreline retreat is not solely an artifact of prolonged droughts alone. Drastic changes to lake health are primarily consequences of aggressive regional water resources development plans, intensive agricultural activities, anthropogenic changes to the system, and upstream competition over water. This commentary is a call for action to both develop sustainable restoration ideas and to put new visions and strategies into practice before Lake Urmia falls victim to the Aral Sea syndrome. [ABSTRACT FROM AUTHOR]

Water allocation is a growing concern in a developing world where limited resources like fresh water are in greater demand by more parties. Negotiations over allocations often involve multiple groups with disparate social, economic, and political status and needs, who are seeking a management solution for a wide range of demands. Optimization techniques for identifying the Pareto-optimal (social planner solution) to multi-criteria multi-participant problems are commonly implemented, although often reaching agreement for this solution is difficult. In negotiations with multiple-decision makers, parties who base decisions on individual rationality may find the social planner solution to be unfair, thus creating a need to evaluate the willingness to cooperate and practicality of a cooperative allocation solution, i.e., the solution's stability. This paper suggests seeking solutions for multi-participant resource allocation problems through an economics-based power index allocation method. This method can inform on allocation schemes that quantify a party's willingness to participate in a negotiation rather than opt for no agreement. Through comparison of the suggested method with a range of distance-based multi-criteria decision making rules, namely, least squares, MAXIMIN, MINIMAX, and compromise programming, this paper shows that optimality and stability can produce different allocation solutions. The mismatch between the socially-optimal alternative and the most stable alternative can potentially result in parties leaving the negotiation as they may be too dissatisfied with their resource share. This finding has important policy implications as it justifies why stakeholders may not accept the socially optimal solution in practice, and underlies the necessity of considering stability where it may be more appropriate to give up an unstable Pareto-optimal solution for an inferior stable one. Authors suggest assessing the stability of an allocation solution as an additional component to an analysis that seeks to distribute water in a negotiated process. [Copyright &y& Elsevier]

Within river basins different social, economic, political and physical subsystems interact. When making decisions, policy makers should be aware of such interactions as any new policy will affect more than one subsystem. To determine the adequacy of a specific management policy, an integrated study is needed of a complicated water management system in the basin considering major physical, social, economic and political aspects. The Zayandeh-Rud river basin, in central Iran with a semi-arid climate and large agricultural, industrial and domestic water uses, is an example of a complicated watershed system where the lack of complete knowledge about all the interacting subsystems has led to failure of the policymakers in addressing the water shortage in the basin. Although water shortages occur fairly soon after completion of each new water source, transbasin water diversion is still the major policy of water planners to address ongoing shortages. System dynamics provides a unique framework for integrating the disparate physical, socio-economic and political systems important to watershed management. This approach is used to comprehend the interactions of different drivers of the problem and to convey the experiences, lessons learned, and perceptions gained during the model development process. A simulation model, built based on causal loop diagrams of the problem, shows that transbasin diversion is not the best and only solution to the problem. The results of the model for different scenarios suggest that various options of demand management and population control can be more effective in addressing the water crisis of the basin when combined with transbasin water diversions, increasing water storage capacity and controlling of groundwater withdrawal. [ABSTRACT FROM AUTHOR]

Economically optimal operational changes and adaptations for California's water supply system are examined for a dry form of climate warming (GFDL CM2.1 A2) with year 2050 water demands and land use. Economically adaptive water management for this climate scenario is compared to a similar scenario with the historical climate. The effects of population growth and land use alone are developed for comparison. Compared with the historic hydrology, optimized operations for the dry climate warming scenario raise water scarcity and total operation costs by $490 million/year with year 2050 demands. Actual costs might be somewhat higher where non-economic objectives prevail in water management. The paper examines the economical mix of adaptation, technologies, policies, and operational changes available to keep water supply impacts to such modest levels. Results from this screening model suggest promising alternatives and likely responses and impacts. Optimized operations of ground and surface water storage change significantly with climate. Dry-warm climate change increases the seasonal storage range of surface reservoirs and aquifers. Surface reservoir peak storage usually occurs about a month earlier under dry-warm climate change. [ABSTRACT FROM AUTHOR]

The authors discuss issues to be considered by water professionals for sustainability monitoring and assessment. They describe sustainable development as a quality issue and a process. They recommend developing processes and tools that help promote sustainability and practicing participatory planning and collaborative, trust-based decision-making based on a common sense of urgency.

This paper presents the first groundwater‒energy‒food (GEF) nexus study of Iran's agronomic crops based on national and provincial datasets and firsthand estimates of agricultural groundwater withdrawal. We use agronomic crop production, water withdrawal, and energy consumption data to estimate groundwater withdrawal from electric-powered irrigation wells and examine agronomic productivity in Iran's 31 provinces through the lens of GEF nexus. The ex-post GEF analysis sheds light on some of the root causes of the nation's worsening water shortage problems. Access to highly subsidized water (surface water and groundwater) and energy has been the backbone of agricultural expansion policies in Iran, supporting employment in agrarian communities. Consequently, water use for agronomic crop production has greatly overshot the renewable water supply capacity of the country, making water bankruptcy a serious national security threat. Significant groundwater table decline across the country and increasing energy consumption underscore dysfunctional feedback relations between agricultural water and energy price and groundwater withdrawal in an inefficient agronomic sector. Thus, it is essential to implement holistic policy reforms aimed at reducing agricultural water consumption to alleviate the looming water bankruptcy threats, which can lead to the loss of numerous agricultural jobs in the years to come. [ABSTRACT FROM AUTHOR]

We convened a workshop to enable scientists who study water systems from both social science and physical science perspectives to develop a shared language. This shared language is necessary to bridge a divide between these disciplines' different conceptual frameworks. As a result of this workshop, we argue that we should view socio-hydrological systems as structurally coconstituted of social, engineered, and natural elements and study the "characteristic management challenges" that emerge from this structure and reoccur across time, space, and socioeconomic contexts. This approach is in contrast to theories that view these systems as separately conceptualized natural and social domains connected by bi-directional feedbacks, as is prevalent in much of the water systems research arising from the physical sciences. A focus on emergent characteristic management challenges encourages us to go beyond searching for evidence of feedbacks and instead ask questions such as: What types of innovations have successfully been used to address these challenges? What structural components of the system affect its resilience to hydrological events and through what mechanisms? Are there differences between successful and unsuccessful strategies to solve one of the characteristic management challenges? If so, how are these differences affected by institutional structure and ecological and economic contexts? To answer these questions, social processes must now take center stage in the study and practice of water management. We also argue that water systems are an important class of coupled systems with relevance for sustainability science because they are particularly amenable to the kinds of systematic comparisons that allow knowledge to accumulate. Indeed, the characteristic management challenges we identify are few in number and recur over most of human history and in most geographical locations. This recurrence should allow us to accumulate knowledge to answer the above questions by studying the long historical record of institutional innovations to manage water systems. [ABSTRACT FROM AUTHOR]

Understanding the complexity and feedbacks among food, energy, and water (FEW) systems is key to making informed decisions about sustainable development. This paper presents qualitative representation and quantitative system dynamics simulation of the water resources system in the Qazvin Plain, Iran, taking into account the energy intensity of water supply and interconnected water use sectors (e.g., urban, industrial, and agricultural). Qazvin Plain faces water resources challenges that are common to arid/semi-arid areas, including frequent droughts, declining surface water and groundwater, and increased urban and agricultural water demand. A system dynamics model is developed using historical data (2006–2016) to investigate the effects of anticipated dynamics of integrated water and energy sectors in the next two decades. The results of policy scenarios (2020–2039) demonstrate that the continuation of the existing management policies will cause severe damage to the water and energy sectors, pushing the system towards water resources limits to growth. An annual groundwater table decline of nearly 1 m is anticipated, indicating significant overshoot of the plain's natural recharge capacity, which may lead to the depletion of recoverable groundwater in the plain within the next three decades. The groundwater table decline will cause energy consumption of water supply to increase by about 32% (i.e., 380 GWh) to maintain irrigated agriculture. It is critical to implement a combination of water demand and supply management policies (e.g., net agricultural water savings and recycling treated wastewater) to delay the problem of water limits to growth in the region. • We present a system dynamics of model integrated water and energy sectors in an agricultural region. • The model facilitates evaluation of water management policies using a food-energy water nexux approach. • Policies that facilitate net agricultural water savings and water reuse can delay groundwater depletion. [ABSTRACT FROM AUTHOR]

Understanding the climatic and direct human drivers of abrupt drying of lakes in many parts of the world is a high research priority, particularly for water resources management and restoration. Lake Urmia, a shallow endemic lake in north-west Iran and one of the major saltwater bodies on earth, has undergone a dramatic decline in its water level (WL) in the past decades, resulting in about 80% of loss in the lake's water content. Different explanations have been discussed regarding the primary cause of this WL decline, including climate change, and regional human-driven land- and water-use changes. This paper reports a comprehensive study of the possible primary drivers of the lake's desiccation. Using classical exploratory statistical methods, the analysis accounts for the relationships between climate change (precipitation P, temperature T), land-surface and hydrological evolution (soil moisture SM, and WL), and vegetation cover (VC) change in the region. The latter includes human-driven changes of irrigation and expansion of agricultural lands. Observations over the period 1981-2015 indicate that the observed variability in P, T, and SM cannot explain the sharp decline in the lake WL since 2000. Instead, land-surface analysis shows VC was nearly doubled after 2000 in the Lake Urmia watershed, indicating that the WL decline is mainly associated with human-driven agricultural increase of VC. The expansion of agricultural activities in the watershed has led to increasing transpiration and hence, total evapotranspiration, decreasing the runoff during the increase in VC (inherently including irrigation, storage, and water diversion). Our results are consistent with similar cases around the world identifying human activities and interventions as the main driver of hydrologic changes, while climate change will likely increasingly contribute to such changes and their impacts in the future. [ABSTRACT FROM AUTHOR]