Search

Worldwide hundreds of millions of people suffer from water, food and energy insecurity in transboundary river basins, such as the Zambezi River Basin. The interconnected nature of nexus is often not recognized in investment planning and many regional policymakers lack adequate tools to tackle it. Future growing demands and climate change add an additional challenge. In this study, we combine policy relevant co-developed stakeholder scenarios and integrated nexus modeling tools to identify key solutions to achieve sustainable development in the Zambezi. Results show that siloed development without coordination achieves the least economic and social benefits in the long term. Prioritizing economic benefits by maximizing the use of available natural resources results in the expansion of irrigated areas by more than a million hectares and increase in hydropower production by 22,000 GWh/year in the coming decades, bringing significant economic benefits, up to $12.4 billion per year, but causes local water scarcity and negative impacts on the environment. Combining environmental protection policies with sustainable investments of $7.2 billion per year (e.g. groundwater pumping and wastewater treatment and reuse, irrigation efficiency improvements, and farmer support aimed to improve food security and productivity) results in significantly higher social benefits with economic benefits that still reach $11.3 billion per year.

Monitoring and estimating spatially resolved changes in soil organic carbon (SOC) stocks are necessary for supporting national and international policies aimed at assisting land degradation neutrality and climate change mitigation, improving soil fertility and food production, maintaining water quality, and enhancing renewable energy and ecosystem services. In this work, we report on the development and application of a data-driven, quantile regression machine learning model to estimate and predict annual SOC stocks at plow depth under the variability of climate. The model enables the analysis of SOC content levels and respective probabilities of their occurrence as a function of exogenous parameters such as monthly temperature and precipitation and endogenous, decision-dependent parameters, which can be altered by land use practices. The estimated quantiles and their trends indicate the uncertainty ranges and the respective likelihoods of plausible SOC content. The model can be used as a reduced-form scenario generator of stochastic SOC scenarios. It can be integrated as a submodel in Integrated Assessment models with detailed land use sectors such as GLOBIOM to analyze costs and find optimal land management practices to sequester SOC and fulfill food–water–energy–-environmental NEXUS security goals.

Reducing water scarcity requires both mitigation of the increasing water pollution and adaptation to the changing availability and demand of water resources under global change. However, state-of-the-art water scarcity modeling efforts often ignore water quality and associated biogeochemical processes in the design of water scarcity reduction measures. Here, we identify cost-effective options for reducing future water scarcity by accounting for water quantity and quality in the highly water stressed and polluted Pearl River Basin in China under various socio-economic and climatic change scenarios based on the Shared Socio-economic Pathways (SSPs) and Representative Concentration Pathways (RCPs). Our modeling approach integrates a nutrient model (MARINA-Nutrients) with a cost-optimization procedure, considering biogeochemistry and human activities on land in a spatially explicit way. Results indicate that future water scarcity is expected to increase by a factor of four in most parts of the Pearl River Basin by 2050 under the RCP8.5-SSP5 scenario. Results also show that water quality management options could half future water scarcity in a cost-effective way. Our analysis could serve as an example of water scarcity assessment for other highly water stressed and polluted river basins around the world and inform the design of cost-effective measures to reduce water scarcity.

The Lancang-Mekong River Basin is facing booming water resources infrastructure development, long-term transboundary conflicts and trade-offs between economic goals and ecosystem services provision. Optimizing the pathway towards sustainable infrastructure operation has lacked multisector-coordinated and decision behaviour-based perspectives for transboundary water systems. In this study we quantified how, and to what extent, transboundary cooperation generates economic and environmental co-benefits by jointly using a coupled simulation–optimization approach and cooperative game theoretical analysis. We found that full cooperation outweighs partial or non-cooperation modes to promote economic benefits by 3 to 21% and to minimize the losses in fishery and sediment transport from 23% and 60% to 12% and 22%, respectively. Full cooperation becomes more beneficial and stable alongside infrastructure expansion, climate change and satisfying the hydrological needs of river ecosystems. These findings underscore the importance of full cooperation for sustaining socio-environmental systems and highlight the need for a benefit reallocation mechanism and designed flow management to stabilize basin-level full cooperation in the Lancang-Mekong River Basin.

On the 23 November 2023, the SOS-Water project held the first stakeholder workshop for the Danube Basin case study. As water challenges increase worldwide, exacerbated by climate change, the SOS-Water project aims to establish a Safe Operating Space (SOS) for water resources, to ensure an adequate, sustainable and clean water supply for both human activities and natural ecosystems. Funded by the European Union's Horizon Europe Framework Programme, the project uses an integrated approach that combines modeling, monitoring, and stakeholder engagement, applied to four different case studies in Europe and beyond. The Danube River basin, known for its ecological and socio-economic diversity, is one of the selected case studies. The workshop convened key stakeholders from various freshwater-related institutions, promoting dialogue and collaboration to address the complex challenges that the basin is facing. During a day of interactive activities, stakeholders collectively identified values, objectives, and priorities essential for sustainable water management in both the entire Danube basin and the Danube Delta. Discussions underscored the need for integrated approaches that balance environmental conservation, socio-economic development, and climate adaptation. Key outcomes include the refinement of objective hierarchy maps that reflect the stakeholder input and priorities collected during the workshop. The next steps will be the development of specific indicators for the objectives. This is followed by the weighting of goals (i.e., objectives) to be achieved through further stakeholder engagement activities and workshops, towards a co-development of the Safe Operating Space for the Danube River basin.

The Mediterranean basin is one of the world’s most vulnerable regions to climate change. The fast rise of temperatures and the decrease of precipitation are some of climate change issues. Aquifers’ recharge will be also decreased in the next century. Hydroeconomic modelling is a suitable tool to analyse the effects of climate change on the future state of groundwater resources at regional scales. Hydroeconomic models of Mahdia Ksour Essef coastal aquifer, Tunisia, were developed to show how climate change affects the groundwater scarcity and farmers’ profits. The models contain hydrological and economic parameters. Six scenarios covering three policies (no cooperation between farmers, partial cooperation regime and full cooperation regime) and two situations (normal conditions and climate change situations) are evaluated. The simulation results show the potential impacts of climate change scenarios on the aquifer water table level, groundwater extractions, crops superficies and famers’ benefits for each policy in the future. The full cooperation regime gives the best results in terms of aquifer sustainability and social welfare mainly under the climate change conditions.

‘Water circles’ are presented as flexible water cycle diagrams aggregating the flows through a system for a specific region and time period, categorized by flow type and organized by magnitude. Water circles for an entire system and separate storage components can be interpreted as water cycle speedometers and can help compare and communicate different climate and human impacts on different regions, time periods, and storage components. Water circles can facilitate comparisons between hydrological models and other methods for deriving water balances.

Groundwater resources play an important role for irrigation, particularly in arid and semi-arid regions, where groundwater depletion poses a critical threat to agricultural production and associated local livelihoods. However, the relationship between groundwater use, farming, and poverty, particularly with regards to informal mechanisms of resources management, remains poorly understood. Here, we assess this relationship by developing a behavioural model of groundwater user groups, empirically grounded in the politically fragile context of Tunisia. The model integrates biophysical aquifer dynamics, institutional governance, and farmer decision-making, all of which are co-occurring under conditions of aquifer depletion and illicit groundwater extraction. The paper examines how community-level norms drive distributional outcomes of farmer behaviours and traces pathways of local system collapse - whether hydrogeological or financial. Through this model, we explore how varying levels of trust and leadership, ecological conditions, and agricultural strategies can delay or avoid collapse of the social-ecological system. Results indicate limits to collective action under path-dependent aquifer depletion, which ultimately leads to the hydrogeological collapse of groundwater user groups independent of social and institutional norms. Despite this inevitable hydrogeological collapse of user groups, the most common cause of water user group failure is bankruptcy, which is linked to the erosion of social norms regarding fee payment. Social and institutional norms, however, can serve to delay the financial collapse of user groups. In the politically fragile system of Tunisia, low levels of trust in government result in low social penalties for illicit water withdrawals. In the absence of alternative irrigation sources, this serves as a temporary buffer against income-poverty. These results highlight the need for polycentric coordination at the aquifer-level as well as income div

Water supply in the Mahdia region of Tunisia originates mainly from groundwater sources. As a common pool resource, these aquifers are highly susceptible to overexploitation, resulting in the classical tragedy of the commons. In this study, a hydro-economic optimization model was developed to determine the most efficient allocation of groundwater resources between farmers in the present and also by considering the needs of future generations. An economic analysis was performed with the model to find efficient policies that contribute to decrease aquifer overuse in normal and drought years and improve its sustainability. Financial analysis of returns and costs of producing irrigated crops were determined in the Mahdia-Ksour Essef aquifer, in which the benefits of drip, flood, and sprinkler irrigation were compared for each crop. The efficiency of alternative scenarios (baseline scenario “no policies undertaken” and water policy scenarios) were compared. Data for the analysis were obtained from multiple sources. Results show the importance of cooperation between farmers. The consideration of pumping costs along time in the farmers’ benefit equation allows the recovery of the water table level over the next two decades. This study assessed the importance of policy interventions to maximize social benefits for sustainable groundwater management. This paper introduced a case application of a dynamic model for managing an aquifer of the Mahdia region in Tunisia. This overused coastal aquifer requires the urgent application of the proposed water policies to maintain groundwater’s natural level and prevent the propagation of saltwater intrusion. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.

A sufficient freshwater supply is vital for humans, ecosystems, and economies, but anticipated climate and socio-economic change are expected to substantially alter water availability. Across Europe, about two-third of the abstracted freshwater comes from rivers and streams. Various hydrological studies address the resulting need for projections on changes in river discharge. However, those assessments rarely specifically account for the impact of various water withdrawal scenarios during low flow periods. We present here a novel, high-resolution hydrological modeling experiment using pseudo-global warming climate data to investigate the effects of changing water withdrawals under 2 K global warming. Especially in Western and Central Europe the projected impacts on low flows highly depend on the chosen water withdrawal assumption and can severely decrease under the worst case assumptions. Our results highlight the importance of accounting for future water withdrawals in low flow projections, showing that climate-focused impact assessments in near-natural catchments provide only one piece of the anticipated response and do not necessarily reflect changes in heavily managed river basins.

In this presentation we discuss methodologies, modeling tools and case studies on linking distributed disciplinary food, water, energy, environmental (FWEE) systems’ models into multi-systems multi-disciplinary integrated models for truly integrated analysis and managing of FWEE security NEXUS. Models’ linkage approaches enable to operationalize the concept of modeling and data platforms for distributed independent models’ “integration” and integrated FWEE security NEXUS management. Local, national and global FWEE security in the presence of climate change and risks of various kinds depend on the consistent coordination between and within the interdependent FWEE systems regarding sustainable resource supply and utilization. Detailed independent sectoral and regional systems’ models are often used to address these challenges. However, the independent approaches overlook the close linkages and feedbacks between and within the systems and, therefore, possible cross-sectoral implications. Critical cross-sectoral FWEE systemic supply-demand imbalances can trigger a disruption in a FWEE systems network. Disruptions and failures can be induced by human decisions in combination with natural shocks. For example, overuse of water in one system, e.g., agricultural, can lead to drying up of wells, decrease of reservoir water level, shortage of water in other systems, e.g., for colling power plants or hydropower production; an extra load in a power grid triggered by a power plant or a transmission line failure can cause cascading failures with catastrophic systemic outages; a hurricane in combination with inappropriate land use management can result in a catastrophic flood and human and economic losses, similar to the induced by Hurricane Katrina. These are examples of systemic risks motivating the development of proper models’ linkage approaches and integrated systems analysis. The linkage algorithms are becoming widely demanded in connection with the need for decentralized pla

Purpose The authors present a dynamic macroeconomic model for assessment of disaster risk reduction (DRR) policies under multiple hazards. The model can be used to analyze and compare various potential policies in terms of their economic consequences. The decomposition of these effects into multiple benefits helps policy makers and other stakeholders better understand the ex ante and ex-post advantages of DRR investments. The purpose of this paper is to address these issues. Design/methodology/approach A dynamic real business cycle model is at the core of this research. In the model multiple natural hazards modeled stochastically cause shocks to the economy. Economic outcomes, most importantly, output can be assessed before and after disasters and under various DRR policies. The decomposition of benefits aims to quantify the concept of triple dividends. Findings In case study applications in Tanzania and Zambia, the authors find that investments into physical infrastructure and risk transfer instruments generate a variety of benefits even in the absence of disaster. A land use restriction with planned relocation for example reduces output in the short run but in the long run increases it. Overall, policy effects of various DRR interventions evolve in a nonmonotonic manner and should be evaluated over a long period of time using dynamic simulation. Originality/value The novelty of this study lies in the economic quantification of multiple benefits described in the triple dividends literature. This helps comparing ex ante, ex-post and volatility-related economic effects of multiple disasters and related physical and financial DRR investment options. As observed in the case studies, the model can also identify overlooked temporal heterogeneity of co-benefits of DRR investments.

This study develops a hydro-economic model for the coastal aquifer Mahdia Ksour Essef in Tunisia in order to analyze how external shocks (climate change, energy price increase) and management policies can affect groundwater sustainability during the coming decades. Twenty-one scenarios covering three management policies (free market, partial cooperation, and full cooperation policy) under various potential climate and economic changes are evaluated. The results of scenario simulations show the potential impact of energy soaring prices and climate change on the aquifer’s water table level, groundwater extractions, cropland areas, and farmers’ benefits under each policy option in the future. They also show that the best scenario to address the effects of climate change would need to take into account environmental externalities and efficient energy prices. The findings of this study are very important in the context of climate change and uncertain global energy markets and provide feasible alternatives to preserve the regional economy and aquifer sustainability.

Hydro-economic modeling (HEM) addresses research and policy questions from socioeconomic and biophysical perspectives under a broad range of water-related topics. Applications of HEM include economic evaluations of existing and new water projects, alternative water management actions or policies, risk assessments from hydro-climatic uncertainty (e.g., climate change), and the costs and benefits of mitigation and/or adaptation to such events. This paper reviews applications of HEM in five different categories: (1) climate change impacts and adaptation, (2) water–food–energy–ecosystems nexus management, (3) capability to link to other models, (4) innovative water management options, and (5) the ability to address and integrate uncertainty. We find that (i) the increasing complexity and heterogeneity of water resource management problems due to the growing demand and competition for water across economic sectors, (ii) limited availability and high costs of developing additional supplies, and (iii) emerging recognition and consideration of environmental water demands and value, have inspired new integrated hydro-economic problems and models to address issues of water–food–energy nexus sustainability, resilience, reliability through water (re)allocation based on the relative “value” of water uses. In the past decade, the field of HEM has improved the integration of ecosystem needs, but their representation is still insufficient and mostly ineffective. HEM studies address how to sustainably manage water resources, including groundwater which has become an area of particular interest in climate change adaptation. The current most used spatial and temporal resolutions (basin-scale and yearly time-step) are appropriate for planning but not for operational decisions and could be underestimating impacts from extreme events (e.g., flood risk) captured only by sub-monthly time scales. In addition, HEM primarily focuses on biophysical and economic indicators but often overlooks p

Study region The Guadalquivir Basin in Spain as a representative Mediterranean basin. Study focus The aim of this study is to assess the adaptive capacity of Mediterranean basins to long periods of severe drought. To do so, a hydro-economic model has been developed that includes a spatial representation of the major economic uses of water and enables an analysis of the economic and environmental effects of alternative water management policies under a single event of water scarcity. New hydrological insights for the region Results highlight the trade-offs among economic uses of water and environmental flow requirements since water resources in the Guadalquivir are fully allocated. Moreover, the increase of irrigated perennial crops area will aggravate vulnerability to drought by limiting the adaptive capacity of the basin. Survival irrigation is the first option for farmers to adapt to the simulated extreme drought. 148,000 ha are shifted from normal irrigation to survival irrigation in the Drought Management Protocol scenario. These findings call for policy interventions to ensure greater management flexibility toward optimising water use while meeting environmental goals. For instance, enabling water trading among farmers would reallocate 22 % more water to the upper basin, reducing drought losses by 22 M EUR. The hydro-economic model developed here can be adapted to basins elsewhere and the results show that it can be a useful tool to guide the design of efficient water management policies to address severe droughts in water-stressed basins.

China is the world’s top water consumer and CO2 emitter. The government has deployed Three Red Lines (TRLs) to improve water security by 2030 and committed to achieving carbon neutrality by 2060. China’s industries, which account for half of national CO2 emissions and >20% water withdrawals, is key to decarbonization and water conservation. However, there remains a lack of consensus regarding whether industrial emission reduction and water saving can be achieved simultaneously. Here, we adopt a general equilibrium model using a self-developed high-resolution provincial water-use inventory based on enterprise census data, to uncover the impacts achieving carbon neutrality would have on industrial water use across China. Meeting carbon neutrality enables the achievement of the TRL-associated industrial water-use target and can reduce industrial water use by 24% in 2060. Nevertheless, if inter-provincial industrial relocation occurs, water use could rise in certain provinces, reducing the above water-saving potential. Stricter and coordinated policies and technological advancements are essential to successfully address climate and water challenges concurrently.

The increasing concern about the degradation of water-dependent ecosystems calls for considering ecosystems benefits in water management decision-making. Sustainable water management requires adequate economic and biophysical information on water systems supporting both human activities and natural ecosystems. This information is essential for assessing the impact on social welfare of water allocation options. This paper evaluates various alternative water management policies by including the spatial and sectoral interrelationships between the economic and environmental uses of water. A hydroeconomic model is developed to analyze water management policies for adaptation to reduced water availability in the Ebro Basin of Spain. The originality in our contribution is the integration of environmental benefits across the basin, by using endemic biophysical information that relates stream flows and ecosystem status in the Ebro Basin. The results show the enhancement of social welfare that can be achieved by protecting environmental flows, and the tradeoffs between economic and environmental benefits under alternative adaptation strategies. The introduction of water markets is a policy that maximizes the private benefits of economic activities, but disregards environmental benefits. The results show that the current institutional policy where stakeholders cooperate inside the water authority, provides lower private benefits but higher environmental benefits compared to those obtained under water markets, especially under severe droughts. However, the water authority is not allocating enough environmental flows to optimize social welfare. This study informs strategies for protection of environmental flows in the Ebro Basin, which is a compelling decision under the imminent climate change impacts on water availability in coming decades.

In this talk we discuss the on-going joint work contributing to the IIASA-NASU 2022-2026 project on “Modeling and management of dynamic stochastic interdependent systems for food-water-energy-health security nexus” [1-3]. The research is being conducted involving the International Institute for Applied Systems Analysis (IIASA, Laxenburg, Austria), Committee for Systems Analysis (NASU, National Academy of Sciences, Ukraine), Glushkov’s Institute of Cybernetics (NASU, Kyiv, Ukraine)), Taras Shevchenko National University, Faculty of Computer Science and Cybernetics (Kyiv, Ukraine), Norwegian University of Science and Technology (Trondheim, Norway). Changing socio-economic and environmental conditions, increasing systemic interdependencies and risks, variability and frequency of weather-related disasters can have adverse impact on regional and global food security and, thereby, Food-Water-Energy (FEW) Nexus security. In this presentation we discuss the importance of appropriate Artificial Intelligence (AI), Statistical and Machine Learning (ML) model(s) for estimating and forecasting crop yield probability distributions relying on Big Data analysis, climate change projections, temperature and precipitation data, soil characteristics, land practices, and socio-economic indicators. Crop yield probability distribution models (scenario generators) can be integrated in agricultural insurance and land use models for the design of crop insurance mechanisms, which play a significant role in agricultural systems’ adaptation to climate change and systemic risks, as a part of the FEW systems’ adaptation strategies such as robust production technological portfolios, irrigation planning. The crop yield and agricultural production models can be linked with land use sectoral and regional models using models’ linkage methodologies based on distributed iterative “learning” optimization algorithms developed jointly by IIASA and NASU [4-8] and utilizing principles of Stochastic Quasigrad

In the context of changing climate and increasing water demand, large-scale hydrological models are helpful for understanding and projecting future water resources across scales. Groundwater is a critical freshwater resource and strongly controls river flow throughout the year. It is also essential for ecosystems and contributes to evapotranspiration, resulting in climate feedback. However, groundwater systems worldwide are quite diverse, including thick multilayer aquifers and thin heterogeneous aquifers. Recently, efforts have been made to improve the representation of groundwater systems in large-scale hydrological models. The evaluation of the accuracy of these model outputs is challenging because (1) they are applied at much coarser resolutions than hillslope scale, (2) they simplify geological structures generally known at local scale, and (3) they do not adequately include local water management practices (mainly groundwater pumping). Here, we apply a large-scale hydrological model (CWatM), coupled with the groundwater flow model MODFLOW, in two different climatic, geological, and socioeconomic regions: the Seewinkel area (Austria) and the Bhima basin (India). The coupled model enables simulation of the impact of the water table on groundwater–soil and groundwater–river exchanges, groundwater recharge through leaking canals, and groundwater pumping. This regional-scale analysis enables assessment of the model's ability to simulate water tables at fine spatial resolutions (1 km for CWatM, 100–250 m for MODFLOW) and when groundwater pumping is well estimated. Evaluating large-scale models remains challenging, but the results show that the reproduction of (1) average water table fluctuations and (2) water table depths without bias can be a benchmark objective of such models. We found that grid resolution is the main factor that affects water table depth bias because it smooths river incision, while pumping affects time fluctuations. Finally, we use the model to

Uncertainty and variability of climate changes are key challenges for adaptation planning. In the face of uncertainty, the decision-making can be addressed in two interdependent stages: make only partial ex-ante anticipative actions to keep options open until new information is revealed; and adapt the first-stage decisions with respect to newly acquired information. This decision-making approach corresponds to the two-stage stochastic optimization (STO) incorporating both anticipative exante and adaptive ex-post decisions within a single model. The paper develops a two-stage STO model for climate change adaptation through robust land use and irrigation planning in the condition of uncertain water supply. The model identifies the differences between the decision-making in the cases of perfect information, full uncertainty, and uncertainty with perspectives of learning about uncertainty. The two-stage anticipative and adaptive risk-informed decision-making with safety constraints induces risk aversion characterized by quantile-based Value-atRisk and Conditional Value-at-Risk risk measures. The ratio between the ex-ante and ex-post costs and the shape of uncertainty 61 determines the balance between the anticipative and adaptive decisions. Selected numerical results illustrate that the alteration of the ex-ante agricultural production costs can affect crop production, land management technologies, and natural resource utilization.

Uncertainty and variability are key challenges for climate change adaptation planning. In the face of uncertainty, decision-making can be addressed in two interdependent stages: make only partial ex ante anticipative actions to keep options open until new information is revealed, and adapt the first-stage decisions with respect to newly acquired information. This decision-making approach corresponds to the two-stage stochastic optimization (STO) incorporating both anticipative ex ante and adaptive ex post decisions within a single model. This paper develops a two-stage STO model for climate change adaptation through robust land use and irrigation planning under conditions of uncertain water supply. The model identifies the differences between decision-making in the cases of perfect information, full uncertainty, and two-stage STO from the perspective of learning about uncertainty. Two-stage anticipative and adaptive decision-making with safety constraints provides risk-informed decisions characterized by quantile-based Value-at-Risk and Conditional Value-at-Risk risk measures. The ratio between the ex ante and ex post costs and the shape of uncertainty determine the balance between the anticipative and adaptive decisions. Selected numerical results illustrate that the alteration of the ex ante agricultural production costs can affect crop production, management technologies, and natural resource utilization.

In Austria, increase in demand as well as climate change might create local and seasonal hot-spots of water stress. It is thus important to understand the status quo and future development of these phenomena to identify potential areas of tension. WaterStressAT assesses water availability and demand in two Austrian case studies under a set of regional development and climate change scenarios.

Sustainable water management is challenging because of the wide range of agents who need water and the different kinds of use, in a context of limited water availability. The availability of water for use, at a given point in time and space, depends on numerous physical and climatic variables, as well as upstream uses and downstream commitments. Therefore, any analysis of water use and management must inevitably be made in the context of such variability. This paper develops an integrated, multiregional, hydro-economic modeling framework to analyze the spatial and temporal dependencies between economic agents in the different regions and areas of a river basin. We combine hydro-economic modeling (partial economic equilibrium) and a multiregional input–output model (general equilibrium) to take advantage of both methodologies. Spatial variability is considered in the input–output models, but variability in both time and space is also considered by the hydro-economic model. Hydro-economic models are used to quantify direct impacts, but not indirect impacts in some specific sectors of the economy, while the input–output model reveals the relationships between all sectors and regions, and facilitates the assessment of total impacts (direct plus indirect) of a range of scenarios. While the methodology described in this paper is applicable to any river basin, the case study considered is the Ebro River Basin, in Spain. To show the potential of the modeling framework, two scenarios are simulated to assess the impacts on water use, value added, and jobs across scales. The results of these scenarios show that decreases in water availability have negative impacts on socio-economic variables (value added and employment). The trade-off between water availability and socio-economic variables depends on the temporal and spatial variability of the resource, and affects each location in the basin in a different way, demonstrating the importance of the methodology developed.

Water scarcity and water quality degradation are major problems in many basins across the world, especially in arid and semiarid regions. The severe pressures on basins are the consequence of the intensification of food production systems and the unrelenting growth of population and income. Agriculture is a major factor in the depletion and degradation of water resources, and contributes to the emissions of greenhouse gases (GHG). Our study analyzes water allocation and agricultural pollution into watercourses and the atmosphere, with the purpose of identifying cost-effective policies for sustainable water management in the Ebro River Basin (Spain). The study develops an hydroeconomic model that integrates hydrological, economic and water quality aspects, capturing the main spatial and sectoral interactions in the basin. The model is used to analyze water scarcity and agricultural pollution under normal and droughts conditions, providing information for evaluating mitigation and adaptation policies. Results indicate that drought events increase nitrate concentration by up to 63% and decrease water availability by 42% at the mouth of Ebro River, highlighting the tradeoffs between water quantity and quality. All mitigation and adaptation policies reduce the effects of climate change, improving water quality and reducing GHGs’ emissions, thus lowering environmental damages and enhancing social well-being. Manure fertilization and optimizing the use of synthetic fertilizers are important cost-effective policies increasing social benefits in a range between 50 and 160 million Euros. Results show that irrigation modernization increases the efficient use of nitrogen and water, augmenting social benefits by up to 90 million Euros, and enlarging stream flows at the river mouth. In contrast, manure treatment plants reduce private and social benefits even though they achieve the lowest nitrate concentrations. Our study provides insights on the synergies and tradeoffs between e

The Jucar Basin faces the challenge of meeting an enormous demand for irrigation while water quality degrades from urban, industrial, and agricultural pollution. Relying on engineering solutions is not enough. Empirical evidence in Jucar indicates that water markets and institutional policies seem to deal with water scarcity more successfully than water pricing and irrigation subsidies. A first water governance priority is to convince farmers of substituting freshwater for the available urban recycled water. Second, seawater desalination plants must be upgraded so they will work at full capacity. More long-term governance goals are to curtail surface irrigation diversions and groundwater extractions, and reallocating water to urban, industrial, and environmental uses. These reforms will only work if they get the support and cooperation of farmers by compensating them for the reallocation of water from agriculture to other sectors.

In the presentation we discuss critical issues related to the design of resilient and robust food, water, energy, environmental systems in the presence of interdependent systemic risks. We introduce the notions of systemic risks, security, resilience and robustness in FWEE systems. We emphasize the need for the two-stage preventive-adaptive stochastic optimization (STO) approaches enabling to design a robust portfolio of precautionary strategic and operational adaptive decisions making the interdependent systems flexible and robust with respect to risks of all kinds. We establish a connection between the robust quantile-based nonsmooth estimation problem in statistics and the two-stage nonsmooth STO problem of robust strategic-adaptive decision making. The coexistence of complementary strategic ex-ante and adaptive ex-post decisions induces systemic risk aversion in the form of Value-at-Risk quantile-based risk constraints. Using examples from research studies on integrated management of catastrophic dependent risks, integrated agricultural-water-energy nexus security, multidisciplinary water resource management we argue that coping with systemic risks can be addressed by solving a system of implicit probabilistic security equations. Selected numerical results from the studies illustrate that a robust combination of interdependent strategic and adaptive solutions presents qualitatively new policy recommendations contributing to the overall welfare increase.

The development of and access to freshwater resources in East Africa is fundamental to the region's sustainable development goals. Following vision documents for regional development and working with local stakeholders, we developed water scenarios up to 2050 that inform the hydro-economic modeling analysis of the extended Lake Victoria Basin, the headwaters of the Nile River. Water scenarios that take an integrated approach to assessing the combined effects of climate change, land use, and increasing human water use suggest that the flow regime of the Nile may remain relatively stable. However, if this stability is to be achieved, while at the same time sufficient water is preserved for healthy freshwater ecosystems, a large fraction of water infrastructure must rely on advanced, often costly technologies and management. Interconnected analyses of both upstream and downstream water resources over time, guided by co-developed scenarios, are indispensable for planning sustainable water-development pathways.

Climate change represents a serious threat to life in earth. Agriculture releases significant emissions of greenhouse gases (GHG), but also offers low-cost opportunities to mitigate GHG emissions. This paper assesses agricultural GHG emissions in Aragon, one important and representative region for agriculture in Spain. The Marginal Abatement Cost Curve (MACC) approach is used to analyze the abatement potential and cost-efficiency of mitigation measures under several scenarios, with and without taking into account the interaction among measures and their transaction costs. The assessment identifies the environmental and economic outcomes of different combinations of measures, including crop, livestock and forest measures. Some of these measures are win-win, with pollution abatement at negative costs to farmers. Moreover, we develop future mitigation scenarios for agriculture toward the year 2050. Results highlight the trade-offs and synergies between the economic and environmental outcomes of mitigation measures. The biophysical processes underlying mitigation efforts are assessed taking into account the significant effects of interactions between measures. Interactions reduce the abatement potential and worsen the cost-efficiency of measures. The inclusion of transaction costs provides a better ranking of measures and a more accurate estimation of implementation costs. The scenario analysis shows how the combinations of measures could reduce emissions by up to 75% and promote sustainable agriculture in the future.

The development of and access to freshwater resources is fundamental if East Africa aims to achieve its goal of increased economic growth. Following vision documents for regional development and working together with local stakeholders, we developed water scenarios up to 2050 that inform the hydro-economic modelling analysis for the extended Lake Victoria Basin, the headwaters of the Nile River. Results indicate a 4-5 fold increase in water demand, especially for expanding irrigation and domestic water needs. Together with climate and land use change, the discharge and flow regime of the Nile will remain relatively stable. However, if this is to be achieved, while sufficient water is preserved for environmental needs, a large fraction of future water infrastructure must rely on advanced, often costly, technological, and management options. The interconnected analysis, between up-stream and down-stream water resources and sectoral water demand, guided by co-developed scenarios, supports planning of sustainable water pathways.

The Water Futures and Solutions Initiative (WFaS) is a cross-sector, collaborative global water project. Its objective is to apply systems analysis, develop scientific evidence and identify water-related policies and management practices, working together consistently across scales and sectors to improve human well-being through water security. The approach is a stakeholder-informed, scenario-based assessment of water resources and water demand that employs ensembles of state-of-the-art socio-economic and hydrological models, examines possible futures and tests the feasibility, sustainability and robustness of options that can be implemented today and can be sustainable and robust across a range of possible futures and associated uncertainties. This report aims at assessing the global current and future water situation.