Sensitivity analysis of incoming sediment load to the reservoirs of the Paranaíba River basin: effects of climate change

Abstract

Climate change poses significant challenges to reservoir sustainability by altering streamflow regimes and intensifying sediment dynamics. This study provides an integrated assessment of the sensitivity of reservoirs in the Paranaíba River basin to increases in incoming sediment load under climate change scenarios that project higher mean annual streamflow. The system‑level assessment covered 64 dams and 47 hydrosedimentometric monitoring stations in operation in the basin at the end of 2024. For each reservoir, stylized climate-change scenarios applied +1%, +5%, and +10% to the annual mean discharge, with increments redistributed across the daily series. Total sediment loads were computed from station-specific power-law rating curves using Colby’s 1957 simplified method; reservoir trap efficiency followed Churchill and Brune. Impacts are heterogeneous across reservoirs; anthropogenic pressure, particularly urbanization, modulates the sensitivity to discharge increases: sub-basins with higher urbanization show larger responses: the total incoming sediment load increased by up to 32.8% at Lago Paranoá, the most affected site owing to the intense urbanization of its drainage area, which includes Brasília and surrounding cities, in contrast to five reservoirs under lower anthropogenic pressure, such as Santa Maria, near the springs of the Ribeirão do Torto. It explicitly accounts for interactions among multiple projects and addresses the lack of system‑scale analyses for cascade reservoirs.

Keywords: cascade reservoirs, climate change, incoming sediment load, Paranaíba river.