Modeling Sediment Transport Potential and Connectivity to Support Sustainable Hydropower Development in Central Asia.

Hydropower development exerts strong pressure on river systems by fragmenting river basins, trapping sediments and creating downstream sediment starvation. These alterations severely degrade river ecosystems through losses in habitat abundance and deterioration of substrate composition. As hydropower continues to expand, there is an urgent need for informed sediment management to be included in hydropower planning. In Central Asia, where a high potential for hydropower development remains, hydromorphological data are limited, constraining the assessment of morphological processes. To address this data scarcity, this study creates for the first time a high-resolution dataset containing qualitative information on sediment transport and sediment connectivity in Central Asia. We modified a sediment connectivity model to work with openly available geospatial datasets and statistically variable input data. The simulation outputs were aggregated into spatially explicit probabilities of sediment transport, entrainment and deposition for five grain-size classes, along with connectivity indices. Comparisons with results from 2D numerical hydraulic modeling at four sites indicated an overall good agreement, although a consistent tendency toward overestimation. The resulting dataset facilitates the decision-making process in hydropower planning by informing three application domains: comparing hydropower sites, deciding on design and operational strategies, and evaluating ecological and morphological impacts. Although site-specific assessments and field data are crucial for individual hydropower projects, our dataset provides essential decision support for basin-wide hydropower development in Central Asia.