Sanjeev Joshi
Cold-water refuges (CWRs) in the Columbia River Basin (CRB) are essential habitats for migrating salmonids and lampreys, yet they are increasingly threatened by sediment accumulation intensified by climate-driven disturbances such as wildfires, glacial retreat, and extreme hydrological events. Despite their ecological importance, long-term sediment transport patterns within CWRs of CRB remain largely unquantified. This study applies the Soil and Water Assessment Tool (SWAT) to simulate multi-decadal hydrological and sediment dynamics in the Klickitat River Basin (KRB), a key CRB refuge. Model calibration against discharge performed well, while suspended sediment concentration was less robust, particularly during validation. Sensitivity analysis highlighted snow-related parameters to be sensitive to discharge, underscoring the snowpack-driven nature of the basin. Results show higher sediment and water yields in upstream headwater sub-basins, with strong discharge–sediment linkages across the watershed. These findings provide the first long-term assessment of sediment trends in a CRB CWR, informing sediment management and supporting tribal-led salmon conservation efforts.