Environmental flows assessment integrating snow trout habitat requirements in the Shakhimardan basin, Central Asia

Abstract The increasing demand for hydropower development in Central Asia threatens the ecological integrity of high-mountain rivers. This study applies an ecohydraulics-based approach to assess environmental flow requirements for a diversion hydropower project on the Koksu River, Uzbekistan. We integrated high-resolution 2D hydrodynamic modeling with novel habitat data for snow trout ( Schizothorax eurycephalus ), incorporating fuzzy logic sets and rules to model habitat preferences across three life stages. Our findings recommend an environmental flow regime that maintains seasonal variability, with base flows ranging from 10.6% to 17.7% of the mean annual flow, ensuring habitat availability during critical life cycle periods. We contextualize the results within adaptive management frameworks by highlighting preliminary results from an ongoing biotelemetry study. This ecohydraulics-based approach provides a replicable model for environmental flow assessments in Central Asia and beyond.