Reshaping the Hirakud Reservoir: Unraveling the impacts of climate change on sedimentation in Eastern India

This study investigates impact of climate change on soil erosion, sediment yield, and reservoir sedimentation, with implications for management and design of reservoirs. The Hirakud Dam on the Mahanadi River in eastern India is used as a case study. The objectives are to quantify sediment inflow under changing climate conditions and to assess spatial deposition patterns within reservoir. An integrated modeling approach is employed, combining Soil and Water Assessment Tool for catchment-scale hydrology and erosion simulation, with TELEMAC–SISYPHE model for reservoir-scale sediment transport. Future climate scenarios are incorporated by downscaling projected rainfall using Statistical Downscaling Model to the local catchment scale. Results indicate a significant shift in peak rainfall from July to April and decreasing trend in monsoon streamflow due to elevated surface temperatures. Numerical simulations reveal formation of finger-like sediment mounds in upstream delta of the Mahanadi River, complete occupation of the Ib River valley by delta, and progressive advancement of sediment mounds toward the dam. Despite these changes, sedimentation rates remain largely unaffected due to stable median annual streamflow in projected period. This study demonstrates critical influence of climate change on reservoir sedimentation patterns and highlights effectiveness of coupled hydrological and numerical models for predicting sediment accumulation.