CASE STUDIES

The SOS framework requires a rigorous assessment of the challenges associated with its multi-dimensional structure. This includes not just multiple indicators, but also multiple scenarios and management pathways. In order to investigate these challenges, SOS-Water will apply the water system assessment framework within five different case study regions. These represent a set of river basins in Europe and beyond that face their own unique set of water challenges under varying environmental and socio-economic conditions, making an excellent test cases for the framework. Specifically, the case studies were chosen to represent the entirety of the most severe and urgent water challenges in Europe and beyond: (i) increasing water scarcity and changing water demand, (ii) the impacts of climate change, (iii) reduced environmental flows and biodiversity loss, (iv) water pollution, and (v) socio-political challenges.

By designing water system SOS within the selected case studies and by assessing the developed water system SOS across scales, SOS-Water will cover a broad range of ongoing and imminent water challenges. That will further support the future implementation of the SOS framework beyond the case studies and scales considered within SOS-Water, enhancing the assessment of future risks and vulnerabilities across scales.

The chosen case study sites are the following:

(i) the Jucar River Basin in Spain;

(ii) the Upper Danube region;

(iii) the global delta of the Danube;

(iv) the global delta of the Rhine River;

(v) the Mekong River Basin in Southeast Asia.

Case Study Insights: What We’ve Learned from the Field

One of the most valuable aspects of the SOS-Water Project is our extensive network of case studies. These real-world examples allow us to test, refine, and implement water management strategies in diverse environments—ranging from transboundary river basins to urban centers grappling with climate adaptation. Our case study research provides scientific insights, predictive models, and policy recommendations to help stakeholders develop resilient and sustainable water management solutions.

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Danube Basin: Managing Transboundary Water Resources

The Danube Basin is Europe’s second-largest river system, spanning 19 countries and serving as a critical resource for industry, agriculture, and ecosystems. Managing water sustainably in such a complex, transboundary setting requires cooperation across political and economic boundaries.

Our research in the Danube highlights a change in length and number of high and low flow events. Climate models project that flooding events may become more severe, particularly in low-lying areas along the river, increasing the need for flood-resilient infrastructure and better forecasting tools. At the same time, rising temperatures and changing precipitation patterns are expected to reduce water availability during summer, threatening agricultural productivity and hydropower generation.

Through stakeholder engagement workshops, we are co-developing sustainable water pathways that balance the needs of urban centers, farmers, energy producers, and conservation efforts. This approach ensures that our recommendations are scientifically robust, but also practical and implementable across national boundaries.

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Mekong Delta: Adapting to Sea Level Rise & Socioeconomic Change

The Mekong Delta is one of the world’s most vulnerable regions to climate change, where millions of people rely on its waters for agriculture, fisheries, and daily life. Our case study focuses on the growing impact of salinity intrusion, a phenomenon where rising sea levels push saltwater further inland, threatening freshwater supplies and rice farming—one of the delta’s economic backbones.

Predictive models developed in the project suggest that flooding patterns will become more unpredictable, with a combination of stronger monsoons and drier dry seasons increasing the risk of both too much water and too little water at different times of the year. Additionally, land subsidence (the gradual sinking of land due to groundwater extraction) is accelerating, making the region even more prone to inundation.

Our research provides policy recommendations for managing water allocation under increasing stress. These include improved irrigation management, freshwater storage solutions, and better planning for land use adaptation to ensure that communities can continue to thrive despite changing environmental conditions.

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Rhine Basin: Urban Water Management & Climate Resilience

The Rhine Basin, home to some of Europe’s most densely populated cities, presents a unique challenge: ensuring water security in rapidly growing urban environments while mitigating climate impacts. One of the most pressing concerns in the region is the urban heat island effect, where city landscapes absorb and retain heat, leading to higher water demand, increased evaporation, and stressed water supply systems.

To address these challenges, the project has investigated the effectiveness of rainwater harvesting, decentralized wastewater treatment, and nature-based cooling solutions such as green roofs and permeable urban surfaces. Our findings suggest that these approaches not only reduce stress on water supply systems but also contribute to flood resilience by reducing surface runoff and enhancing groundwater recharge.

Lessons learned from this case study emphasize the importance of adaptive infrastructure planning, where cities proactively integrate water-sensitive design into new developments and retrofitting efforts. By adopting smarter water use policies, urban centers in the Rhine Basin can enhance their long-term climate resilience and improve overall water efficiency.

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Júcar River Basin: Water Scarcity in Mediterranean Climates

The Júcar River Basin in Spain is an example of the intensifying struggle with water scarcity in Mediterranean climates. With increasingly prolonged droughts and growing demands from agriculture, tourism, and urban centers, the basin faces a critical need for improved water allocation strategies.

Our research in the Júcar Basin focuses on modeling to predict water availability trends, helping water managers make more informed and adaptive decisions. Findings suggest that groundwater levels are declining at an unsustainable rate, requiring better recharge strategies and improved efficiency in agricultural water use.

One of the key recommendations emerging from our research is the optimization of groundwater recharge strategies. This includes using treated wastewater for irrigation, restoring natural aquifer recharge zones, and promoting water-efficient farming practices. The project is also working closely with local stakeholders to develop policy frameworks that encourage sustainable water use, ensuring that both economic activities and natural ecosystems can coexist under future climate scenarios.

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Bringing Local Insights to a Global Scale

The findings from our case studies not only provide local solutions but also contribute to the global understanding of water sustainability. By studying water challenges in diverse geographic and climatic conditions, the SOS-Water Project is building a comprehensive knowledge base that can inform policies and water management strategies worldwide.

These case studies showcase that successful water management is not just about technical solutions—it requires collaboration, stakeholder engagement, and long-term planning. As we continue refining our research, we aim to translate these insights into actionable strategies that can be scaled and adapted for different regions facing similar challenges.

Stay connected as we share more results, practical applications of our research, and policy recommendations to help secure a Safe Operating Space for Water.