Securing Water, Energy, Food & Ecosystems in the Júcar River Basin District, Spain

Key Learnings

About the Region

Figure 1. Jucar River Basin District. Image Credit: REXUS.

Climate Threats

The Júcar River Basin faces several challenges due to climate change, such as droughts, extreme temperatures, water scarcity and heavy rain. Combined with population growth, unsustainable water management practices and competing demands for natural resources, climate change is leading to erosion, reduced soil health and biodiversity loss. Water scarcity and irregular rainfall threaten agriculture, urban water supply, and energy production, making effective water resource management essential to ensure food, water, and energy security while preserving the ecosystem. In October 2024, the Dana Floods showed the devastating impact heavy rains can have on the region’s ecosystems, infrastructure and communities. Projections estimate that climate change will severely reduce water availability, making immediate action essential.

A clear roadmap with preventive measures, integrating science, society, and policy, and increasing coordination and financial capacities can support climate resilience. To achieve this, opportunities for adaptation exist via EU-aligned strategies, conservation, and innovation. The image below shows the natural landscape of the Júcar River, showing the natural landscape of the region (Figure 2).

Figure 2: The Jucar River. Image Credit: REXUS.

What is the "WEFE Nexus"?

Jucar Basin Applications: Adaptation Approaches and Mechanisms

The Water-Energy-Food-Ecosystem (WEFE) Nexus provides an integrated approach to managing interconnected resources, which is especially relevant for water-stressed regions such as the Jucar Basin in Spain.

WATER FOOTPRINT AND WATER ACCOUNTING

In recent years, remote sensing techniques have facilitated identifying water stress. Targeted water management approaches use this information to monitor crop conditions and optimise irrigation practices, helping to assess agricultural water requirements. Data on domestic and industrial consumption feed into water use databases and support the development of accurate environmental water footprint indicators. The “Water Footprint” considers water metrics such as green water from rainwater use (Figure 3), blue water for irrigation (Figure 4) and grey water, defined as water required to dilute pollutants to meet water quality standards. Remote sensing contributes to calculating the water footprint by providing spatially explicit information on land use patterns, vegetation growth, and crop yields.

Figure 3. Green Water Footprint (rainwater use) over Júcar River Basin District. Image Credit: REXUS.

Figure 4. Blue Water Footprint (irrigation) over Júcar River Basin District. Image Credit: REXUS.

While the ‘agricultural water footprint’ provides an indicator of the green, blue, and grey water consumed in crop production, ‘agricultural water accounting’ refers to the systematic quantification of actual water inflows, withdrawals, consumption, and return flows within a basin. In practice, footprint data can inform accounting processes, but water accounting has a broader scope as it connects these indicators with basin-scale allocation, planning, and management.

Agricultural water accounting in the Júcar Basin allows precise quantification of the water demands of different crops in the Júcar Basin. Assessing needs at various scales, from individual plots to entire irrigation districts, integrating water accounting with water footprint analysis, and embedding these methods into the Júcar Basin Hydrological Plan, 3rd period 2022-2027, has promoted data-driven and climate-resilient water management. This integration allows water managers to align allocations more closely with actual crop demands and adapt to climate variability. Close collaboration between the project team and the Júcar River Basin Authority, local water user associations such as the “Junta Central de Regantes de la Mancha Oriental (JCRMO)”, and municipal water managers enabled fruitful outcomes in joint workshops, technical meetings, and field demonstrations. These collaborations improved water allocation accuracy, reduced over-extraction, and fostered stakeholder trust and knowledge exchange. The results have informed decision-making, supporting the adoption of efficient irrigation practices and the prioritisation of water allocations during drought events. Incorporating these considerations into basin management plans has strengthened the region’s resilience to ongoing climate challenges.

Figure 5. Agricultural Water Footprint over Jucar River Basin District. Image Credit: REXUS.

PARTICIPATORY SYSTEM DYNAMICS MODELLING FOR POLICYMAKERS

In the Júcar River Basin, a participatory system dynamics modelling framework has marked a significant shift in understanding and addressing complex watershed challenges. Over the past three years, the project team, under CNR-IRSA’s lead, has developed the framework, using Casual Loop Diagrams (Figure 6) to visualise cause-and-effect relationships and support the transition from nexus thinking to Nexus action. Systems thinking encourages viewing the basin as an interconnected asset, where changes in one area affect the entire system. Encouraging stakeholders to co-create these diagrams captures valuable on-the-ground insights. The diagrams show how policy, climate, and local practices interact to shape outcomes across the basin.

The approach identifies challenges and sectoral conflicts and pinpoints policy leverage points (Table 1). Tackling unauthorised groundwater extraction is a prime example: even minor changes, such as improved monitoring or community-led reporting, can have a strong impact. The measures can restore balance to groundwater levels, enhancing ecosystem health, and ensuring long-term water security for all users. Computer simulations (scenario modelling) help stakeholders understand the potential impacts of their decisions on other sectors, supporting holistic thinking and maximising overall benefits.

Rather than relying solely on top-down technical assessments, Participatory System Dynamics Modelling brings together diverse stakeholders, such as farmers, urban water users, environmental groups, industry representatives, and public agencies, to collectively map the complex interconnections that define the region’s water, energy, food, and ecosystem Nexus. Stakeholder engagement fosters collaboration, builds trust and ensures topic relevance while addressing stakeholder needs and reducing potential conflicts.

Figure 6. Project collaboration in the Jucar Basin: Creating CLDs, identifying resources and risks, and teamwork. Image Credit: REXUS.

The mapping exercise depicted interconnections within the WEFE Nexus and revealed gaps, such as underrepresented energy-related questions. The exercise involved participatory workshops in which stakeholders and experts jointly developed causal maps linking water availability, agricultural practices, hydropower production, ecosystem services, and food security. The process highlighted the strong influence of irrigation efficiency on groundwater quality and ecosystem health, while also revealing that energy linkages – such as electricity demand for pumping or the use of renewables in irrigation – are insufficiently addressed in existing assessments. Expert input and targeted literature searches were used to refine and complement these missing elements. The exercise enabled stakeholders to understand interconnections and develop better-suited policies for the basin. Improving water quality and supporting ecosystem services involves stricter groundwater monitoring using smart meters and remote sensing and promoting Nature-based Solutions like constructed wetlands. Encouraging sustainable farming practices, such as cover cropping, crop rotation, no-till methods, and organic farming, also helps protect soil and maintain healthy wetlands. These policies foster cross-sectoral collaboration and adaptive management, addressing immediate challenges and long-term resilience in the Júcar Basin.

Table 1: water, energy, food, and ecosystem nexus challenges at the Júcar River Basin and associated leverage points.

The Participatory System Dynamics Modelling assessment combines scientific and local knowledge to map complex intersectoral relations. Casual Loop Analysis combined with Graph Theory, which creates and shows a network of points and lines, reveals challenges and leverage points to design effective policies, encouraging long-term adaptation and tailored actions.

While these advances have laid the groundwork for more adaptive and inclusive governance, the journey is ongoing. The next steps involve making these approaches even more accessible and useful for stakeholders. Further developing quantitative system dynamics models, simulating the impacts of different policy decisions, ensures the insights gained from participatory modelling translate into real-world action.

Testimonials from Key Stakeholders

The nexus assessment allows us to achieve a sustainable transition, by meeting demands as well as achieving environmental objectives, with more coordination between the different levels of competence and the different sectors.

Laura Tanco, River Basin Authority

Scientific tools like REXUS give policymakers confidence and direction. Organisations and public administrations must utilise these tools to offer the necessary support. Often, the general public may not see this directly, but without research, we would be adrift.

Herminio Molina, Farmer and Former president of Irrigators board

The adaptation actions brought together local, regional and national stakeholders – including municipalities of Palma de Gandia and Albacete, Regional Governments (Valencia and Castilla La Mancha), the river basin authority (CHJ), irrigation communities (Junta Central de Regantes de la Mancha Oriental, FENACORE), the Ministry of Agriculture, Fisheries and Food (MAPA), the Ministry for the Ecological Transition (MITECO), agricultural cooperatives, farmers, energy providers and NGOs.

The project team facilitated participatory workshops and technical meetings, developed decision-support tools, and co-designed adaptation measures tailored to the basin´s unique risks. A key outcome is the implementation of the REXUS Water Footprint in the Basin 3rd cycle Hydrological Plan.

Summary

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