Hydro operational optimisation of dam reservoirs based on evaporation sensitive release scenarios under climate driven water stress

Abstract

Increasing climate-driven water stress has intensified evaporation losses from dam reservoirs, posing significant challenges to sustainable water resources management and long-term reservoir performance. Conventional reservoir operation policies often neglect the dynamic role of evaporation under changing climatic conditions, leading to suboptimal release strategies and reduced water supply reliability. This study develops an evaporation-sensitive hydro-operational optimisation framework that explicitly integrates climate-induced evaporation dynamics into reservoir release decision-making under water-stressed conditions. The proposed framework couples reservoir mass balance equations with evaporation-responsive release scenarios derived from observed hydro-meteorological data and climate-adjusted operational constraints. Multi-scenario optimisation is implemented to evaluate the trade-offs between water supply reliability, storage sustainability, and evaporation-induced losses under varying inflow and climatic conditions. The optimisation structure is designed to remain applicable to large multi-purpose reservoirs, where operational flexibility is constrained by competing water demands and hydrological uncertainty. Evaporation sensitivity is incorporated through dynamic adjustment of release rules based on seasonal evaporation intensity, storage–surface area relationships, and projected water stress indicators. The framework enables adaptive modification of release patterns during high-evaporation periods, thereby reducing unnecessary surface exposure and long-term storage depletion. Performance indicators including storage resilience, volumetric evaporation loss, and operational efficiency are assessed across alternative release scenarios. The methodological approach advances existing reservoir optimisation studies by explicitly linking evaporation processes with operational decision variables, rather than treating evaporation as a fixed loss term. Results demonstrate that evaporation-aware release strategies can substantially improve reservoir performance under climate-driven water stress, particularly during prolonged dry periods. The framework provides a practical decision-support tool for reservoir operators seeking to enhance water use efficiency and climate resilience without structural modifications to existing infrastructure. The findings contribute to the development of adaptive reservoir operation policies capable of addressing increasing evaporation risks under future climatic conditions.