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Abstract

The Water-Energy-Food-Environment (WEFE) nexus supports integrated, cross-sectoral analysis of socio-environmental challenges. Multiple nexus sectors in the Lake Victoria Basin (LVB) already experience significant stress, and climate change will likely intensify these pressures. Current WEFE nexus tools remain relevant but do not use process-based modelling or stakeholder-driven indicator development. Without these components, it is difficult to account for local knowledge systems and priorities. They also miss key biophysical dynamics that shape historical and future conditions.
This study introduces a new approach that uses participatory methods and process-based modelling to develop a stress-analysis tool for the LVB. Indicators selected by stakeholders were operationalised by soft-coupling an eco-hydrological and land management model with a lake-ecosystem model. This enabled quantitative analysis of 77 \% of high-priority indicators and improved existing WEFE methodologies. The framework assessed historical stress patterns, explored mid-century changes under two climate scenarios, and offers temporal and spatially explicit insights into future vulnerabilities. Our framework is transferable to data-scarce, transboundary systems and demonstrates the value of integrating participatory approaches with process-based modelling. 
Multiple stress hotspots already exist across the nexus in the LVB. Future projections show both intensification and expansion of stress hotspots that concentrate in densely populated, transboundary regions. Degradation of water quality, lake biodiversity, and agricultural productivity, combined with increased land degradation, will expose more people to important nexus stresses, rising from about 15.5 to up to 20.1 million under future scenarios. This underscores the need for regional cooperation and adaptation measures.