Society and ecosystems are deeply connected to, and through, hydrological processes. Significant research efforts have revealed the breadth of ways humans have become dominant drivers of the global water cycle, however less attention has been placed on how hydrological change will affect social and ecological systems at the global scale. Understanding both directions of this coupled social-ecological system are critical to achieving sustainable freshwater futures in complex, multi-objective decision making environments. Here, we identify the global hotspots for social and ecological impacts from freshwater stress and freshwater storage loss.

We applied the concept of hotspot mapping, from the field of conservation biogeography, to integrated socio- and eco-hydrological considerations for the first time at the global scale. We identified 168 basins for global prioritisation that are most vulnerable to suffer social and ecological impacts from freshwater stress and storage loss. These basins encompass over 1.5 billion people, 17% of global food crop production, 13% of global gross domestic product, and hundreds of internationally significant wetlands (Ramsar sites). The impacts that can be realised in these basins include transgressed environmental flows, increased drought frequency, decreased ecological resilience, threatened water, economic, and food security through reduced freshwater availability, and increased risk of wells running dry which may exacerbate existing economic inequalities. Regions and nations home to hotspot basins include: Argentina, northeastern Brazil, southwestern USA, Northern, Eastern, and Southern Africa, the Middle East and Arabian Peninsula, the Caucasus, West Asia, northern India, Nepal, Pakistan, Southeast Asia, and northern China.  

The 168 hotspot basins present an initial set of regions to prioritise in global sustainability initiatives that link water, ecosystems, and society, such as the Sustainable Development Goals. Furthermore, the hotspots represent the multiple epicentres where management of trade-offs between social, economic, and ecological water uses is most crucial, and thus represent the regions where implementation of integrated water resources management (IWRM) practises becomes most critical.  To this end, we compared IWRM implementation levels to our global vulnerability results. While no direct relationship was found between IWRM implementation and social-ecological vulnerability to freshwater stress and storage loss, we observed, among hotspot basins, that IWRM implementation is lower in transboundary basins than in non-transboundary basins, suggesting that greater multilateralism and cooperation are needed. 

We identified hotspot basins by integrating global socio-hydrological and eco-hydrological datasets, remote sensing observations of freshwater storage trends, freshwater use, and streamflow datasets into a basin-scale social-ecological vulnerability analysis. This presentation reports the findings from Huggins et al. (in press, Nature Communications), and the hotspot basin results are available online for use by policy and research communities.

Freshwater stress and storage loss are only two of many important aspects of freshwater with broad social-ecological resilience implications. Developing a network of similar analyses based on other processes and attributes, such as intra- and inter-annual storage variability, and water quality considerations, will support a more comprehensive understanding of the social-ecological impacts of global hydrological change.

How to cite: Huggins, X., Gleeson, T., Kummu, M., Zipper, S. C., Wada, Y., Troy, T. J., and Famiglietti, J. S.: Vulnerable basins for global prioritisation: Hotspots for social and ecological impacts from freshwater stress and freshwater storage loss, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10611, https://doi.org/10.5194/egusphere-egu22-10611, 2022.

Water resources infrastructure plays an important role in energy and food security by providing water storage for hydropower generation and food production. Yet, Water, Energy, and Food (WEF) often interplay and evolve dynamically over time with social-economic development and water system expansions. Understanding the WEF Nexus is particularly challenging in transboundary contexts, where interdependencies also develop across multiple riparian countries. In this work, we investigate how to address the WEF Nexus in transboundary river basins to discover innovative solutions mitigating existing tradeoffs and facilitating international agreements. Our approach is demonstrated on the Nile River basin, where we explore tradeoffs between power generation and irrigation water supply across Ethiopia, Sudan, and Egypt. In particular, we analyze innovative portfolios of interventions that combine the coordinated operation of large water reservoirs (i.e., the Grand Ethiopian Renaissance Dam, Merowe Dam, and High Aswan Dam) and the main irrigation diversions, with water demand management options (e.g., aquaponics systems, new desalination plants) for reducing the water demand in the Nile Delta. Our results show that the Nile River basin features both strong tradeoffs and notable synergies across the WEF Nexus and across countries. For example, our analysis shows a clear tradeoff between hydropower generation in Egypt and irrigation water supply in Sudan. In contrast, the hydropower generation in Sudan and Egypt are positively correlated. Additional challenges will be generated by the projected decrease in water availability as suggested by most climate change scenarios. Finally, the potential reduction of the irrigation demands in the Nile Delta can contribute in mitigating existing tradeoffs and represents an additional option in the current international negotiations between Ethiopia, Sudan, and Egypt.

How to cite: Yang, G., Giuliani, M., Matta, E., Piuri, V., and Castelletti, A.: Dynamic Water-Energy-Food nexus management in transboundary river basins incorporating water infrastructure operation and demand control, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3040, https://doi.org/10.5194/egusphere-egu22-3040, 2022.

Historically, overcoming energy deficits or increasing water security has translated into a demand for more dams. However, the construction and conventional operation of dams have had contradictory outcomes, negatively impacting natural riverine ecosystems and riparian communities. In the Lower Volta River Basin in Ghana, the construction of the Akosombo dam, with a residence time of 3.9 years, led to the formation of the largest artificial lake by surface area and the resettlement of 80,000 people. Furthermore, the riverine ecosystem changed, as did the lives of the downstream communities who lost their traditional livelihoods. In contrast, the Akosombo dam is credited for powering Ghana’s industrialization and making it one of the more developed countries in West Africa. Thein lies the issue: there exists a trade-off between anthropogenic water demands such hydropower, irrigation or recreation on the one hand, and water for river ecosystems and services on the other. A transparent approach to managing these trade-offs between multiple water users is therefore needed to operate dams equitably. In this study, an Evolutionary Multi-Objective Direct Policy Search (EMODPS) is applied to case of the Lower Volta River Basin to identify the multi-sectorial trade-offs that exists between water users.  A designer environmental flow is incorporated as an objective rather than as a constraint and additionally, different policy framings and scenarios encompassing climate change and varying energy futures are investigated. This study highlights the challenges faced by dam operators in balancing water demands, and also identifies synergies and opportunities for compromise in the Lower Volta River.

How to cite: Owusu, A., Zatarain Salazar, J., Mul, M., van der Zaag, P., and Slinger, J.: Multi-objective trade-off analysis in operating dams for the environment: The case of the Lower Volta River, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7842, https://doi.org/10.5194/egusphere-egu22-7842, 2022.

Hydropower and other renewable energy sources are experiencing new investments for capacity expansion to provide clean and accessible energy to a growing population in many world areas. As most of the untapped hydropower potential lies in developing countries, here, strategic dam planning is critical in supporting the design of capacity expansion with reduced impact on interconnected water, food, and climate systems.

This is true especially for Africa, where more than 300 new hydropower projects are under consideration, and future population growth projections and associated energy, water, and food demands are highly uncertain.

In this work, we investigate how to strategically plan hydropower capacity expansion at the African continental scale, providing an estimate of future hydropower capacity needs. Specifically, we model the energy system using The Electricity Base Model for Africa (TEMBA), based on the OSeMOSYS energy modelling framework, and we consider capacity factors for each hydropower project reported in the African Hydropower Atlas as derived from the hydrologic simulation of the SWAT model that accounts for irrigation demand. To explore different socio-economic and climate policy projections, we also downscale final energy demands projections at the country level from the SSP database. We then investigate two different planning approaches: first, using scenario analysis, we examine how the different individual projections influence hydropower and power system development; second, we adopt a two-stage robust optimization methodology to develop a robust capacity expansion plan common for all the socio-economic and climate policy scenarios until 2035. Finally, we hypothesize that uncertainty about the socio-economic scenario is resolved, and we model the adaptation of the capacity expansion strategy to each of the narratives considered in the period 2035-2050 by solving a new optimization problem.

Our results show that not all the 100 GW of hydropower projects considered in the African Hydropower Atlas are needed to satisfy the final energy demands. Furthermore, as we observe large variability in hydropower capacity expansion under different socio-economic projections, we produce a short-term robust plan extracting the most relevant hydroelectric projects via robust optimization. Finally, we show that adapting capacity planning decisions based on new information can strongly reduce the price of robustness.

Our work proposes a methodology for taking planning decisions in an integrated assessment context where scenarios are used to link different societal sectors and resources. When the uncertainty spanned by plausible future states of the world is large and diverging, a combination of robust optimization and adaptive planning can reduce the potential for bad societal outcomes.

How to cite: Carlino, A., Wildemeersch, M., Giuliani, M., and Castelletti, A.: Hydropower capacity expansion in the African continent under different socio-economic and climate policy scenarios, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12703, https://doi.org/10.5194/egusphere-egu22-12703, 2022.

Dam development projects cumulatively alter natural river connectivity, e.g., for fish and sediment, resulting in cumulative negative externalities across different spatio-temporal scales. Strategic siting of dams combined with dam-scale management, e.g., drawdown flushing for sediment passage, can help mitigate these impacts.

Designing optimal reservoir management strategies for multiple dams (i.e., dam portfolios), which account for economic objectives as well as sediment connectivity, is rarely done due to the lack of specifically designed modelling tools to properly quantify the hydro-morphological response of river systems to water and sediment management schemes. Models designed for this purpose must retain both a basin-scale perspective (to capture cumulative impacts of multiple dams) and a dynamic time representation (to capture dynamic reservoir operations).

This work presents a novel approach to reduce trade-offs between hydropower and sediment through integrating both optimal site selection and optimized joint operation of selected dam sites for sediment flushing. To estimate basin-wide sediment delivery and transport and quantify the effect of reservoirs on it, the study uses a new version of the D-CASCADE model, a process-based basin-scale dynamic sediment transport model.

The study focuses on the 3S river system, a data-scarce tributary of the Mekong river, where major dam development is ongoing. First, (1) the D-CASCADE model is set up and compared to available evidence of grain sizes and transport rates in the network. Then, (2) the effect of reservoir management is explored for different, pre-defined dam development portfolios focusing on downstream reservoirs, assessing daily sediment transport and delivery. Reservoirs features (i.e., volume, energy generation, and sediment storage) are dynamically simulated via integrated modelling add-ons. Finally, (3) sediment management (through drawdown flushing) is optimized by including parameters specific to the timing, frequency, and design of drawdown flushing into the operation rules.

Modelled network sediment yields matching field data measurements are identified and used as a baseline scenario to which to compare dam impacts on sediment delivery. Without sediment management, the model estimates a reduction in network sediment yield to the Mekong river of 32%-57%, depending on the dam portfolio. Sediment management portfolios showcase how reservoir sedimentation and downstream sediment starvation can be mitigated via well-designed flushing operations, albeit at a non-indifferent loss in energy production.

How to cite: Tangi, M., Bizzi, S., Schmitt, R., and Castelletti, A.: Balancing sediment connectivity and energy production via optimized reservoir sediment management strategies, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8778, https://doi.org/10.5194/egusphere-egu22-8778, 2022.

We are increasingly confronted with drought damage in agriculture and nature as well as an increasing pressure on the availability of water for high-grade applications such as the production of drinking water. Strategies are being developed to control these risks and to secure long-term supplies of freshwater. These include increasing regional self-sufficiency in meeting the demand for freshwater and improving the utilization of the available water sources. We provide examples of adaptation measures to reduce the gap between water demand and availability under climate and water use changes, including reuse of water resources across sectors. Water reuse has the potential to substantially reduce the demand on groundwater and surface water. We present an integrative framework to evaluate the potential of water reuse schemes in a regional context and demonstrate how water reuse propagates through the water system and potentially reduces pressure on groundwater resources. The use of Sankey diagram visualisation provides a valuable tool to explore and evaluate regional application of water reuse, its potential to reduce groundwater and surface water demand, and the possible synergies and trade-offs between sectors. The approach is demonstrated for the Dutch anthropogenic water system in the current situation and for a future scenario with increased water demand and reduced water availability due to climate change. Four types of water reuse are evaluated by theoretically upscaling local or regional water reuse schemes based on local reuse examples: municipal and industrial wastewater effluent reuse for irrigation, effluent reuse for industrial applications, and reuse for groundwater replenishment. Doing so, we share a general framework for developing strategies to integrate water reuse in a robust regional water system. Responsible water reuse requires a multidisciplinary approach with knowledge on water demand and availability, water quality and health, technology and governance. Systematic evaluation of these aspects can help determine when water reuse is, or is not (!), a viable part of a regional strategy. This integrative context, including water systems thinking and modelling to identify risks and benefits, is essential for a successful implementation of water reuse in practice.

How to cite: Bartholomeus, R., Pronk, G., Stofberg, S., Krajenbrink, H., and Raat, K.: Increasing water system robustness: potential of cross-sectoral water reuse, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-929, https://doi.org/10.5194/egusphere-egu22-929, 2022.

Water resources supply is closely related to food production and economy development. The importance of such a complex system is increasingly recognized in academia and policy. An integrated System Dynamics Model for the water-stressed Loudi city in Hunan Province, China, assessing water balance, and agricultural yield and revenue to 2050, is presented. Considering the uncertainty of future inflows, the formulation of water supply policies, and changes in cropping regimes, this study simulated multiple scenarios to better understand the impacts on water, food, and economic security and their interactions to highlight Loudi's realization of potential pathways to a more sustainable future. Current water resource over-exploitation can be mitigated while still allowing for agricultural development. While most simulations hinted at continued over-exploitation, some suggested that improvements can be achieved by altering parameters such as per-capita domestic water demand, per-capita industrial water demand and the cropping regime. Relevant policies should be considered in parallel to introduce redundancy into the policy framework. From initial results, it is hypothesized that by producing excess crops, a virtual water trading market can be developed, thereby further improving water balance, yield and revenue. This study used system dynamics as a powerful tool to explore complex, feedback-driven water-food systems, providing a viable framework for water resource management approaches and policies at the regional scale.

How to cite: Wang, X., Susnik, J., and Dong, Z.: Research on integrated modeling of a coupled regional water-food systems based on system dynamics, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3217, https://doi.org/10.5194/egusphere-egu22-3217, 2022.

Several studies have explored the interaction across the water, energy, and land (WEL) systems under the scope of policy analysis, highlighting the importance and usefulness of integrated approaches in exploring pathways for achieving the Sustainable Development Goals (SDGs) in the WEL sectors. However, most of these studies neglect the possible impact of climate change on the natural system (e.g. water cycle and crop yields changes) or on technologies (e.g. power plant potentials, desalination, etc.) because of the high complexity, interconnection and uncertainty of these impacts.
Using the latest version of the MESSAGEix-GLOBIOM Integrated Assessment Model (IAM), we study the long-term resources, supply and demand of the energy, water and land sectors to determine the regional and sectoral investments required for achieving the SDGs. Here we show the implications of climate feedbacks for different regions and sectors under different climate mitigation scenarios. The largest component of climate impacts, and the highest source of uncertainty, are changes in water availability, which affect irrigation, provision of basic water and sanitation access, hydropower potential and the available technology options for cooling power plants.

How to cite: Vinca, A., Awais, M., Byers, E., Fricko, O., Frank, S., Satoh, Y., Krey, V., and Riahi, K.: The role of multi-sector climate impacts in achieving water, energy, and land SDGs , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11450, https://doi.org/10.5194/egusphere-egu22-11450, 2022.

Climate water stress internationally challenges the goal of achieving food, energy, and water security.  This challenge is elevated by population and income growth and by considerable uncertainty about future water supplies. Increased climate water stress levels reduce water supplies in many river basins and intensify competition for water among sectors and over time periods.  Organized information is needed to guide river basin managers and stakeholders who must plan for a changing climate through innovative water allocation policies, trade-off analysis, vulnerability assessment, capacity adaptation, and infrastructure planning. Several hydroeconomic models have been developed and applied assessing water use in different sectors, counties, cultures, and time periods.  However, none to date has presented an optimization framework by which historical water use and economic benefit patterns can be replicated while showing measures to adapt to future climate water stresses to inform the design of policies not yet implemented. This paper’s unique contribution is to address this gap by designing and presenting results of a hydroeconomic model for which optimized base conditions match observed data water use and economic welfare for several urban and agricultural uses at several locations in a large European river basin for which water use supports a population of more than 3.2 million.  We develop a state-of-the arts empirical dynamic hydroeconomic optimization model that integrates hydrology, economics, climate stress, and institutional water sharing measures. The model is used to discover land and water use patterns that optimize sustained farm and city income under various levels of climate-water stress. Findings using innovative model calibration methods allow for the discovery of efficient water allocation plans as well as providing insight into marginal behavioral responses to climate water stress and water policies. Results show that a water trading policy for handling climate water stress provides more economically efficient water use patterns, reallocating water from lower valued uses to higher valued uses such as urban water.  The Ebro River Basin in Spain is used as an example to investigate water use adaptation patterns under various levels of climate water stress. That basin’s issues and challenges light a path to relevance for other river basins internationally.

How to cite: Baccour, S., Ward, F., and Albiac, J.: Hydroeconomic Analysis for Climate Adaptation Guidance under Future Climate Water Stress, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4423, https://doi.org/10.5194/egusphere-egu22-4423, 2022.

Climate change disrupts weather patterns in various ways across the world, leading to an increased variability in rainfall and therefore water availability, which in turn exacerbates water scarcity. At the same time, a growing population and rising GDP increases the demand for food and the demand for water in agriculture and other sectors. While 40% of agricultural production comes from irrigated systems, and represents 20% the total cultivated land, large-scale assessments of climate change impacts on agricultural production and food security typically focus on direct crop yield effects only. The increased water scarcity through an increased demand and a decreased supply for irrigation water is likely to impact agricultural production, leading to cascading effects on consumption, markets, and food security.

Using an integrated impact chain including climate, hydrology, crop, and economic models, we present the results of a fully integrated assessment of the climate change impacts on both crop yields and water availability relying on the most recent CMIP6 climate change projections to analyze the impacts of irrigation as an adaptation measure for climate-induced yield losses and socio-economic increased demands. Using the Community Water Model (CWatM) we simulate changes to water availability for irrigation under various climate and socio-economic scenarios. Using the Environmental Policy Integrated Climate model (EPIC) model, we assess the impact of climate on yield under irrigated and rainfed systems. The availability of water and requirements for irrigated and rainfed crop production are subsequently integrated in the Global Biosphere Management Model (GLOBIOM) model to assess the uptake of irrigation as an adaptation mechanism and the probability, location, and extent of agricultural water scarcity hotspots, where available water resources fail to meet the agricultural demand, considering also demands from non-agricultural sectors. The model further assesses the consequences of subsequent changes in production, consumption, market, and highly productive areas that coincide with water scarcity hotspots under climate change. Areas with a surplus of water are also identified as potential irrigation investment locations.  

Results show that, by the mid-century, water use for irrigation is projected to increase worldwide. Brazil, China, Canada, Europe, and South-East Asia are expected to use over 40% more water for irrigation compared to 2000 in the high-emissions RCP 8.5 scenario. In contrast, water available for irrigation is diminished in Brazil and other regions in South and Central America as non-agricultural water demand increased. Non-agricultural water demand constrained the water available for irrigation in India and Sub-Sharan Africa as well. The irrigation water use in Europe and Canada are expected to occur at expenses of environmental flow requirements. 

How to cite: Arbelaez Gaviria, J., Palazzo, A., Boere, E., Havlik, P., Burek, P., Balkovič, J., and Trnka, M.: Present and future water scarcity hotspots for rainfed and irrigated agriculture under climate change: a global study. , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12235, https://doi.org/10.5194/egusphere-egu22-12235, 2022.

Over recent decades major advances have been made in global hydrological modelling underpinned by progress in high-resolution data availability, as well as in computational and data storage capabilities. These advances have provided hydrologists with opportunities to develop high-resolution large-scale hydrological models (LHMs) designed to represent and study the global hydrological cycle. However, with the aim of answering relevant questions for water resources policy and management, LHMs have recently been used in a number of regional applications. This has been enabled by their increasing spatial resolution which makes it possible to zoom-in on specific regions, essentially removing the barriers between global and regional models.

Notwithstanding their growing sophistication, the current generation of LHMs still fall short in their ability to represent dynamic trade-offs in the water-food-energy-environment nexus, and water competition between upstream and downstream users. These limitations hinder the ability of LHMs to provide reliable insights at any scale other than the global, leaving the task of incorporating human water management activities within these models as one of the grand challenges for the hydrologic research community.

Catchment-scale water management models (CWMMs) adopt a holistic systems approach to comprehensively address water availability, use, infrastructure, and policy aspects within multi-sectoral water allocation. The coupling of these models with LHMs can enhance their representation of human interventions in the natural water cycle (e.g., management of reservoirs, intra- and inter-basin water transfers) and improve the accuracy of water demand estimations such as irrigation requirements by including irrigation schemes. The inclusion of this local knowledge into LHMs’ modelling process can, therefore, increase their capacity to support rigorous nexus analyses to inform water policy and management decisions.

This work represents the preliminary outcome of a project with the overall research objective of developing and providing a “proof-of-concept” to explore and design an approach for integrating CWMMs with LHMs, and to assess its potential and limitations to enhance the quality of information LHMs provide at regional scale. This work will present the initial efforts to compare the outcomes of LHMs from the Inter-Sectoral Impact Model Intercomparison Project and the CWMM AQUATOOL in the Ebro River basin, a heavily managed catchment in Spain with multiple competing water uses. This comparison will provide an estimate of the capacity of LHMs to provide useful information for decision making, as well as to identify knowledge gaps to be filled with management models.

How to cite: Haro Monteagudo, D., Momblanch, A., Burek, P., Kahil, T., Andreu, J., Paredes-Arquiola, J., Solera, A., and Beguería, S.: Enhancing global hydrological models with local knowledge to support Nexus analyses, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11027, https://doi.org/10.5194/egusphere-egu22-11027, 2022.

In Central Asia, more than 90 % of annually renewable water resources are consumptively utilized in irrigation, and allocation conflicts between large-scale hydropower in the upstream and irrigation in the downstream occur regularly and mostly across complex international borders, especially during water scarce years and low storage conditions. With increasing attention on climate-neutral hydropower solutions, including on small-scale hydropower
(< 10MW), the water-energy-food-environment nexus is now under renewed focus in the region. In line with these developments, new nexus tradeoffs emerge that need to be yet acknowledged and quantified, also under the considering of a changing climate.

As part of the ongoing EU Horizon 2020 Project Hydro4U that demonstrates innovative and sustainable hydropower solutions targeting the unexplored small-scale hydropower potential in Central Asia, a new online nexus toolbox with an innovative monitoring and accounting methodology is developed. It assimilates data from different sources, including from remote sensing and through local monitoring, to monitor and predict water availability and energy production in the mountainous zones of runoff formation and irrigation water use in the downstream. Target user groups are Basin Irrigation System Administrations, private and public energy stakeholders, and Ministry of Water representatives in the two demonstration sites where small-scale hydropower plants are built as part of the project.

Irrigation water use is monitored using an innovative unsupervised machine learning technique for mapping crop-disaggregated irrigated areas at the catchment scale. State-of-the-art datasets on evapotranspiration and biomass production are used for the detailed analysis of crop water demands and irrigation efficiencies in conjunction with local scheme-level water use where available. All processing steps were implemented in Google Earth Engine (GEE), enabling to process large amounts of irrigated crop statistics at a high spatial resolution for the entire semi-arid Central Asia region, including Afghanistan.

In relation to water availability and renewable energy, hydropower production at the demonstration sites is modeled using hydrological modeling using the HBV model. Discharge is forecast at decadal (10-days) to monthly time scales using data from the NOAA NCEI Global Forecasting System product and information on the development of the catchment scale snow cover from the MODIS Snow Cover Daily Global 500m product in the zones of runoff formation.

The nexus toolbox is a web-based tool that can deliver unique and objective data and intelligence to local stakeholders and decision-makers, off-farm and on-farm alike. The advantage of such technology is that no local infrastructure, beyond a computer connected to the internet, is required to access these types of data and intelligence relevant for irrigation improvements is required. The software can be specifically tailored (through an iterative co-design approach) to the needs and wants of stakeholders at all levels, from farmers to Water User Associations on the consumer side and from service providers at district, Province, and National levels. It will also contribute to designing climate-proofed benefits sharing regimes considering uncertainties explicitly to ensure optimal and fair resource use and distribution across the different domains and countries and, therefore, contributing to regional cooperation and peace.

How to cite: Siegfried, T., Anarbekov, O., Ragettli, S., and Marti, B.: Accountability and Transparency through Water-Energy-Food Nexus Accounting in Central Asia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7012, https://doi.org/10.5194/egusphere-egu22-7012, 2022.

Setting upper limits to water consumption per river basin is crucial for ensuring sustainable water use. A blue water footprint cap is an upper limit to the consumptive use of surface and groundwater. A method to determine monthly blue water footprint caps in a river basin as a whole has been proposed (monthly natural runoff minus environmental flow requirements). However, the question remains how to translate caps for a river basin as a whole to caps for each sub-catchment within the basin. A relevant question, because human interventions in rivers have reduced water scarcity in upstream parts of river basins, but aggravated it in downstream parts. We apply two alternative water allocation scenarios to translate blue water footprint caps for the Yellow River basin to caps per sub-catchment and evaluate their effects on upstream-downstream differences in water scarcity: (i) the population-based scenario takes the relative population size per sub-catchment as the basis for water allocation, which makes sense from the perspective of equity and fair sharing of natural resources; (ii) the demand-based scenario takes the historical water demand as the basis for water allocation, which is an option to consider for river basin managers aiming to reduce environmental flow violations. Both scenarios make use of the fact that blue water can be reserved (not consumed) in an upstream sub-catchment for consumption further downstream. We measure the effects of the scenarios against a base case in which sub-catchments are allowed to consume all available water after considering environmental flow requirements without the consideration of downstream uses: the use-what-is-there principle. We find that blue water scarcity increases from upstream to downstream under the use-what-is-there principle. Both the population- and demand-based scenarios reduce upstream-downstream differences in the degree of blue water scarcity. The demand-based scenario is most effective in this respect. On the other hand, the population-based scenario leads to the smallest upstream-downstream differences in water availability per capita. The results feed into a discussion on how to translate upper-limits to water consumption from the river basin to the sub-catchment level which needs to take place for cap-setting to become a practical instrument in river basin management.

How to cite: Schyns, J., Albers, L., and Booij, M.: Translating blue water footprint caps for a river basin to caps per sub-catchment: trade-offs between upstream-downstream uses and the environment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9224, https://doi.org/10.5194/egusphere-egu22-9224, 2022.

Agriculture is essential for economic growth in the Lower Mekong River basin (LMB), which plays a key role in ensuing water and food security of the riparian regions and provides livelihoods for tens of millions of people. Agricultural irrigation, hydropower development, increasing water demand from other sectors, and ecosystem protection necessitate taking a holistic approach when analyzing irrigation in the LMB. This paper examines the existing problems and opportunities of irrigation in the LMB from the angle of water-food-energy (WFE) nexus. We selected journal articles from the Web of Science database and imported them into CiteSpace, a bibliometric analysis software for visual exploration of scientific literature. The visualized results summarize the significance of authors and their affiliations in the selected body of literature, and the country-wise distribution. Four key research themes of LMB irrigation were identified based on the bibliometric analysis, for conducting an in-depth review. First, we investigated the factors that influence agricultural water management which directly affects irrigation water demand and supply as well as crop productivity. This part of the literature focused on water and land management and applications of various models to assess impacts on crop yields of irrigation management. Second, from the literature we analyzed the identified impacts of human flow alternations on downstream water uses, ecosystem health, and land subsidence due to groundwater overdraft. Nevertheless, upstream water management can mitigate downstream flood damages and augment dry-season water supply. Third, the spatiotemporal mismatch between water demand and supply pose a serious challenge for transboundary river basin management. Moreover, inappropriate water utilization, mismanagement and poor governance appear to be the more fundamental causes of the LMB water problems, thus calling for sound agricultural water policies within a riparian country and effective water management cooperation strategies across the riparian countries.  Fourth, despite of the relatively few publications on the Mekong’s WFE nexus so far, this particular topic is gaining growing attention in the Mekong basin research community. Moreover, it offers a valuable holistic perspective for analyzing irrigation in the LMB, by considering its connections with the food and energy sectors in one way or another, compared against many existing studies that view irrigation as solely an agricultural water management problem.

How to cite: Wang, G. and Zhu, T.: A Review of Irrigation in the Lower Mekong Basin: Opportunities and Challenges from a Water-Food-Energy Nexus Perspective, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8202, https://doi.org/10.5194/egusphere-egu22-8202, 2022.

Water shortage and soil salinization are main limiting factors in agricultural production in arid and semi-arid regions worldwide. Located in western Inner Mongolia of China, the Hetao Irrigation District (HID) is the largest gravity-fed irrigation district in Asia and one of the top three largest irrigation districts in China. Irrigation water overuse and high level of soil salinity are the main challenges that curb agricultural productivity, adversely affect farmers’ revenues, and threaten long-term sustainability of irrigated farming in the HID. Nevertheless, irrigation water allocation, salt leaching and accumulation, crop productivity and farming decisions are intrinsically connected and thus necessitate taking a holistic approach to investigate into the interactions among all those factors and devising appropriate technological, management and policy interventions. Towards this goal, an integrated hydro-agro--economic optimization model was developed to optimize water allocation among sub-irrigation districts, across stable and cash crops, and in the four irrigation events of a year that are unique for the HID. The model optimizes net revenue of the HID considering water and salt balance, the response of crops to salinity and water stress, land availability, and existing irrigation management practices that have been proved effective. The Positive Mathematical Programming (PMP) approach is used to calibrate the model such that it can reproduce base year observations of crop acreage, water uses and production costs and benefits, making the model suitable for evaluating alternative management and policy scenarios. Sensitivity analysis were conducted for initial groundwater table, initial soil salinity level and leaching coefficient, and the results were moderately sensitive to initial soil salinity and marginally sensitive to groundwater table and leaching coefficient values. Scenario analyses were conducted to analyze the effects of irrigation water supply, winter irrigation (non-growing period) water application, irrigation efficiency and crop commodity market prices. We found that water supply reduction increases land fallow and reduces net revenue. Winter irrigation can store soil moisture to increase summer crop planting areas and increase salt-leaching to lower crop salinity stress. However, irrigation water use efficiency improvement can cause unintended negative consequences, such as exacerbated soil salinization. Higher crop commodity market price increases planting areas and water allocation of the crop but reduce areas and water uses of other crops, leading to a “crowding-out” effects. These results and modeling exercises provide a holistic perspective and useful insights for future water, land and salinity management, irrigation infrastructure investment, and market risk management in the HID.

How to cite: Cao, Z. and Zhu, T.: Hydro-agro-economic Optimization of Water and Land Management in the Hetao Irrigation District, China, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4054, https://doi.org/10.5194/egusphere-egu22-4054, 2022.

Managing water, energy and food adopting a nexus approach is crucial to guarantee the sustainable and efficient use of resources, particularly in light of global changes. Ecosystem Services (ESs), namely the multiple benefits that ecosystems provide to human well-being, constitute a useful perspective to look at the critical interactions occurring between Water-Energy-Food (WEF). ESs have been rarely explicitly addressed in nexus assessment, however representing the bio-physical foundation of the WEF interactions, they can be used as common assessment endpoints permitting to better disentangle and manage cross-sectoral synergies and trade-offs. The UNTWIST project (MSCA-IF) proposes an innovative approach to look at the WEF nexus through the lens of ecosystem services theory gaining insights about potential interdependencies between sectorial policies and thus unlocking opportunities for delivering integrated solutions towards the achievement of multiple Sustainable Development Goals (SDGs). Starting from the nexus framing, a participative approach is adopted for engaging local stakeholders’ representative of different nexus sectors in identifying existing conflicts in water use and prioritizing ESs they value the most. Later, ARIES (Artificial Intelligence for Environment and Sustainability), an Artificial Intelligence modeler based on the semantic web, is used to develop an integrated model to spatially-temporally represent most relevant ESs and flows exchanged through the WEF nexus building on available sectoral data and models. The proposed approach permits to map critical areas for multiple ESs provision to WEF and thus to identify where synergies and trade-offs between sectors are likely to arise. Based on this results, different scenarios describing multiple combinations of social, economic and climatic pathways are tested serving as the basis for the definition of a shared management strategy for long-term nexus sustainability. Preliminary insights derived from the application to two different case studies in Europe (i.e. Po river basin (Italy), Pas Miera Ason river basins (Spain)) will be presented to discuss the novelty and implications of the proposed approach.

How to cite: Sperotto, A., Villa, F., Balbi, S., and Bagli, S.: Assessing Water-Energy-Food nexus synergies and trade-offs:  an ecosystems services-based perspective , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5169, https://doi.org/10.5194/egusphere-egu22-5169, 2022.

Austria is well endowed with water resources where the total water demand consumes only 3% of the total water supply. However, with increased water demand from agriculture, domestic and industrial sectors and increased frequency of high heat and drought occurrences from future climate change, several regions can potentially face high water stress for short periods in a year which is detrimental to the economy and the environment. The Seewinkel region located in eastern Austria is one such case where both agriculture and environment are dependent on a reliable quantity of water to be available throughout the year. Apart from precipitation, additional crop water requirement is satisfied using an irrigation infrastructure. Groundwater which is the sole source of irrigation water in the region is pumped based on the water allocations prescribed to each irrigation cooperative in the region. These allocations currently limit groundwater withdrawals for potentially higher agricultural output and maintain the natural Seewinkel wetland supported by groundwater body. With climate change induced water stress in the future, sufficient water table levels cannot be maintained throughout the year whil​e simultaneously trying to satisfy agricultural and environmental water demand. Our study identifies different cost optimal management strategies to optimally manage the groundwater resources shared between multiple irrigation cooperatives in the region. Some of the strategies include optimal crop-land mix, irrigation technology transitions, building new water supply infrastructure and using financial instruments. Additionally, the study aims to identify the nature of the shared common pool of groundwater to identify the potential of trading water allocation rights between irrigation cooperatives which can lead to efficient water use. The strategies have been identified based on the stakeholder interviews conducted in the region under the WaterStressAT project KR19AC0K17504 funded by the Austrian Climate Research Program twelfth call.

How to cite: Sahu, R. K., Kahil, T., Guillaumot, L., Burek, P., Hangar-Kopp, S., Karabaczek, V., Offenzeller, M., and Lindinger, H.: Reducing future water stress in the Seewinkel region in Austria: exploring water management opportunities for the sustainable use of the shared groundwater resource., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11170, https://doi.org/10.5194/egusphere-egu22-11170, 2022.

An erratic water supply is a limiting factor for crop production. In several world regions, switching from rainfed to irrigated agriculture has allowed farmers to increase production robustly and stabilise agricultural yields. Yet, in sub-Saharan Africa - the world region with the fastest demographic growth - extensive rain-fed still agriculture accounts for more than 90% of agricultural land, more than one-in-six people are undernourished, and electricity access mostly lacks in rural areas. Previous assessment revealed significant solar irrigation technical potential in the region thanks to the large availability of water supply sources and high solar irradiance. To assess the economic feasibility of this large-scale transformation, here we conduct a high-resolution assessment of solar irrigation solutions, comparing system costs with potential revenues. We estimate and locate the share of rainfed cropland in SSA could be equipped with solar irrigation while ensuring groundwater sustainability and calculate the relative payback time. In addition, we estimate how and to what extent the transition could positively impact food security, in term of kilocalories, and protein and fat grams per capita per year. Our analysis supports public and private actors working along the water-energy-food-economy nexus wishing to identify economic feasibility areas, quantifying the potential net economic benefit of developing solar irrigation, and fostering investment for a synergetic achievement of the Sustainable Development Goals. 

How to cite: Falchetta, G., Semeria, F., and Tuninetti, M.: Quantifying the economic feasibility of solar irrigation in sub-Saharan Africa, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1621, https://doi.org/10.5194/egusphere-egu22-1621, 2022.