A Nexus-Based Approach to Water Resources Assessment: Practical Application of the WEAP Model in Tajikistan

To address climate change and population growth, Central Asia must urgently adopt a holistic water resource management strategy, moving beyond traditional sectoral approaches to embrace a water-energy-food-ecosystems (WEFE) nexus approach.  The WEAP model, a key research tool, integrates hydrological data and socioeconomic factors to create scenarios considering glacier melt, irrigation expansion, and energy generation. WEAP, unlike hydrological models, highlights unmet demand, demonstrating the sectoral impacts of water scarcity for decision-makers. The Nexus approach uses the WEAP model to optimize the Vakhsh hydropower cascade (Nurek and Rogun plants), balancing energy security, environmental flows, and predictable agricultural water supply. The WEAP model assesses innovative irrigation technologies in the Zarafshon basin to enhance food security and cross-border cooperation between Tajikistan and Uzbekistan. The scenario analysis shows that modernizing irrigation systems reduces the burden on the ecosystem and ensures stable harvests even in dry years. Integrating climate forecasts into WEAP allows for water availability scenarios, enabling adaptation measures like optimized cropping and expanded runoff management. WEAP modeling in the Vakhsh and Zarafshon basins highlights the importance of cross-sectoral considerations for water resource management in Tajikistan, providing a basis for sustainable water system decisions.