A nexus approach can support the transition to sustainability by addressing trade-offs and pursuing synergies to improve water, energy, and food security. In this paper, a participatory system dynamics model was developed to identify and assess the key interlinkages between water, food, and energy in Andalusia (Spain). A panel of relevant stakeholders contributed to all stages of the model’s development. Further, by calibrating the model to CAPRI-Water projections until 2050, the evolution of the system under a plausible climate scenario, as well as effects of water prices changes, was evaluated. The results revealed a close link between water cost, irrigation water use, energy consumption, and the economic development of agriculture in the region. Large variability was observed in the effects of water pricing policies across crops. This paper concludes that a participatory system dynamics model can help in understanding the nexus synergies and can support the design of more coherent sustainability strategies in the region.

<p>Climate change and increased pressure on natural resources have been identified as some of the major challenges that will affect Europe in the coming decades. This will cause consequences such as migration, food price shocks, water scarcity and imbalances in energy markets. Food and energy security require large amounts of fresh water. Water is one of the essential resources in both sectors, acting as a crucial driver for irrigation. The demand for natural resources is likely to increase over the coming decades due to growing global population numbers and economic development. At the same time, climate change may lead to lower overall water availability. Consequently, water scarcity, variability and uncertainty are becoming more prominent, which could lead to vulnerabilities within the energy and food sectors. In this sense, The EU is promoting initiatives to address water scarcity, such as investments to improve water use efficiency and the reuse of wastewater for irrigation. The objective of this research is twofold. Firstly, we assess the impact of changes in irrigation water availability, crop water requirements and yields under climate change on EU agriculture. Secondly, we analyse how promoting the reuse of treated water for agriculture may contribute to the reduction of water stress in coastal areas.</p> <p>Using agro-economic modelling (CAPRI), we implement climate change scenarios (RCP7.0 and RCP8.5) - taking into account not only yield changes but also changes in irrigation water availability and crop water requirements - to assess the impact of climate change on agricultural production and water stress across EU regions (NUTS2 regions). Furthermore, to capture the contribution of water reuse for irrigation to mitigate climate change impact on water scarcity, we simulate scenarios with increased treated water potential as an additional water supply at NUTS 2 level.</p> <p>Results provide insights into how climate change impacts agricultural production, food prices and international trade. For example, irrigation water availability limitations with a reduction in crop yields in some heavily irrigated Southern regions could necessitate reversion of cropland from irrigated to rainfed management. However, climate change could lead to increased irrigated cropland in some less water stressed regions. The reuse of reclaimed water is an opportunity to favour the management and efficient use of water resources and can be a solution to water deficit problems. Model results reveal the potential of treated water as an alternative supply source to address water stress and promote sustainable water management under climate change in the EU provided that some conditions are met. It is necessary to invest in the construction of purification infrastructures in areas where there is no control of discharges, as well as in infrastructures that bring this water closer to the consumers. A price competitive with traditional water sources must be achieved in order for its use to become widespread. It is essential to achieve consumer acceptance of the product obtained through the use of reclaimed water, influencing farmers’ decision-making.</p> <p>Acknowledgements:  This research has received funding from the European Union’s Horizon 2020 research and innovation programme under the GoNEXUS project (grant agreement No 101003722). </p> <p> </p>

To enhance water, energy, and food security and promote ecosystems conservation, it is necessary to design policies or solutions capable of addressing cross-sectoral challenges. In this paper, GoNEXUS SEF, an evaluation framework for co-designing and evaluating nexus solutions, is presented. This framework provides guidelines for conducting a nexus-coherence assessment to improve the governance of the water-energy-food-ecosystems nexus. The assessment involves a participatory process that integrates qualitative and quantitative methodologies through systemic approaches. The crucial aspects necessary in the development of methodologies that address the nexus have been identified and considered. The framework was applied to a practical case study, an increase in the irrigation water price in Andalusia—Spain for the horizon of 2030. Case study results revealed that the measure can generate synergies since it favours water savings, irrigation water efficiency and ecosystems conservation. However, trade-offs are observed, mainly undermining the economic development of agriculture in the region. GoNEXUS SEF has proven capable of evaluating nexus solutions by measuring cross-sectoral synergies and trade-offs. It highlights hidden properties and identifies leverage points and key aspects of a complex cross-sectoral system to apply nexus solutions more effectively to promote sustainable development. In addition, the framework can be adapted to fit different case studies, considering their own challenges and their spatial and temporal scales, which gives it a competitive advantage over other methodologies focused on analysing the nexus. Graphical abstarct

<p>Currently, achieving food, energy and water security, and the conservation of ecosystems, are some of the main sustainability challenges. Traditionally, in these sectors, the policy measures and decisions have been taken separately, causing a lack of coordination and high trade-offs across sectors. Consequently, it is necessary to design policies or solutions capable of addressing cross-sectoral challenges. The water-energy-food-ecosystems nexus (WEFE nexus) approach analyses the impacts generated by socioeconomic activities on the production, consumption and management of water, energy and food resources, and the interrelationships with ecosystems. In this sense, the use of this approach can facilitate the identification of coherent solutions that promote the transition toward sustainability.  In this study, an evaluation framework for co-designing and evaluating nexus solutions (GoNEXUS SEF) to improve the governance of the WEFE nexus is presented. GoNEXUS SEF is a new methodological framework developed by the authors and has five main phases: (1) identify nexus solutions; (2) nexus dialogues; (3) model toolbox; (4) nexus evidence; and (5) nexus-coherence assessment. For its development, the ability to evaluate at different spatial scales and forecast at different temporal scales through data projections has been considered. GoNEXUS SEF is a participatory process that integrates qualitative and quantitative methods. On the one hand, we engage stakeholders and experts from the different nexus sectors to understand the cross-sectoral interlinkages, identify challenges, and co-design solutions. On the other hand, we apply system dynamics models (SDM), cross-impact analysis (CIA), and network theory to quantify the synergies and trade-offs.</p> <p>The framework was applied to a practical case study, an increase in the irrigation water price in Andalusia – Spain for the horizon 2030. Case study results revealed that a water price change could generate synergies since it favours water security and ecosystem conservation. However, trade-offs are observed, mainly undermining the food sector in the region. The main difficulties in applying the framework are the integration of qualitative and quantitative information and the conciliation of the spatial and temporal scales across sectors. Beyond the results obtained, the evaluation of this case allowed us to examine the applicability, usefulness, and potential of the framework. GoNEXUS SEF has proven capable of evaluating nexus solutions; it highlights hidden properties and identifies leverage points and key aspects of complex cross-sectoral systems. In addition, it allows the evaluation and coordination of multiple policies at the same time; in that sense, it can help to achieve nexus-coherence policymaking. The framework can be adapted to fit different case studies, considering their own challenges and their spatial and temporal scales, which gives it a competitive advantage over other methodologies focused on analysing the nexus. Participatory approaches, that combine qualitative and quantitative methods, are adequate to identify and evaluate solutions that aim to improve nexus governance.</p> <p><strong>Acknowledgements:</strong>  This research has received funding from the European Union’s Horizon 2020 research and innovation programme under the GoNEXUS project (grant agreement No 101003722). </p>

<p>To make coherent policies and strategies in the water-food system, it is necessary to analyse the synergies and trade-offs based on indicators approach. Policy coherence is considered a fundamental part of the EU’s contribution to achieving the sustainable development goals (SDGs) and calls for addressing the interlinkages between various SDGs. In this research, key indicators have been identified to analyse policy coherence within the water-food system in Andalusia (Spain). Furthermore, food and water policy scenarios have been simulated using a system dynamics model to evaluate future water-food trends by 2050. These provide a better understanding of how relevant policies are linked, which in turn helps to conduct integrated policy analyses and develop coherent policies and programmes across various dimensions of sustainable development.</p><p>In this region, water availability is a limiting factor for food production. Significant synergies and trade-offs were identified between water saving indicators and food production. An increase in water price causes a decrease in the irrigated area, as well as in irrigation water use. However, water pricing policies also increase crop irrigation water productivity. Agricultural policies that promote alternative sources of water, such as the reuse of treated wastewater, contribute to mitigating water scarcity, especially in the context of adaptation to climate change.</p>