Joint water-supply and hydropower management in a capacity-depleted multipurpose reservoir: the two-input AD-2I–WE model for Akhangaran

Abstract Reservoir sedimentation alters not only geometric storage but also seasonal carryover capacity, the physical meaning of legacy rule curves, and hydropower operating conditions. This study integrates repeated elevation–area–volume surveys (1972–2022), a 2,192-day operational record (2020–2025), a quality-controlled 1988–2023 inflow–outflow archive, measured downstream-tributary volumes, and daily hydropower records for the Akhangaran Reservoir, Uzbekistan, within a single adaptive decision framework (AD-2I–WE) driven by two open inputs: current storage and the annual irrigation order. Storage at the normal pool level declined from 197.7 to 169.4 million m³ between 1972 and 2022, a loss of 28.3 million m³ (14.3%). Three water-management benchmarks were compared: an observed-operation stress test (W0), a fixed-terminal-storage optimization (W1), and the adaptive AD-2I model with a 15 million m³ intra-annual safety floor (W2). Under W0, mean volumetric reliability was 69.72% and the mean deficit was 240.08 million m³/year, with 68.3% of the deficit concentrated in July–September. Under its base 313.5 million m³ irrigation order, W2 raised volumetric reliability to 76.05% and cut the deficit by 20.9% relative to W0 while maintaining the safety floor in every year. Lexicographic re-timing of hydropower releases (AD-2I–WE) increased energy from 41.18 to 55.16 GWh/year (+33.9%) without degrading the water-security solution, although modeled energy remained 22.0% below observed 2022–2024 generation. A 63.08 million m³ forced spill in the wet year 2022 revealed a structural constraint imposed by reduced storage and turbine conveyance capacity. The results demonstrate that adaptive, two-input operation can jointly improve water security and hydropower value in a capacity-depleted multipurpose reservoir.

Hali tarjima qilinmagan