Assessment of the Water-Energy-Food-Ecosystem Nexus under Diverse Socioeconomic and Climate Scenarios: The Upper Sakarya River Basin Case

Abstract Submission: The complex issues of water scarcity, energy demand, declining crop yields, and environmental degradation are critical challenges of the 21st century. This study addresses these challenges through the Water-Energy-Food-Ecosystem (WEFE) nexus framework, focusing on the Upper Sakarya River Basin in Türkiye, a region characterized by significant agricultural activity. A methodology was developed to evaluate the WEFE nexus under varying climatic and socioeconomic conditions, with particular emphasis on the often-ignored ecosystem component. Climate data were downscaled using the WRF model, while socioeconomic factors were represented through Shared Socioeconomic Pathways (SSPs). Three scenarios—RCP4.5_SSP1, RCP4.5_SSP2, and RCP8.5_SSP5—were developed and assessed using the integrated WEAP-LEAP model. The results indicate that municipal water demand will not be fully met, with baseline water availability consistently higher than in all future scenarios. The SSP1 scenario shows the largest water deficit due to prioritizing environmental flows, while the SSP2 scenario exhibits a continuous decline. Energy production remains low across all scenarios, with SSP1 performing best through the use of renewable energy, while SSP2 and SSP5 rely exclusively on thermal power. Agricultural irrigation deficits are projected to increase, with SSP2 performing better than other scenarios, though still falling short of baseline levels, and SSP1 experiencing the largest shortfall due to strict environmental regulations. The SSP1 scenario achieves the highest ecosystem health score, while SSP2 and SSP5 only meet environmental flow needs during low-flow months. Overall, the WEFE Nexus Index is the highest for SSP1, driven by stronger performance in ecosystem and energy pillars.

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