Soil erosion and sedimentation challenge water resources management in semiarid regions, where extreme climatic conditions and inadequate land use amplify these issues. These processes compromise reservoir storage, water quality, and regional sustainability. This study evaluates their impacts on reservoirs (Mulungu, Caldeir & atilde;o de Parelhas, V & aacute;rzea Grande, Esguicho, Itans, Cruzeta, S & atilde;o Jo & atilde;o do Sabugi, and Boqueir & atilde;o de Parelhas) in the Serid & oacute; River Basin, Brazil, using hydrosedimentological modeling based on the Universal Soil Loss Equation (USLE) and sedimentation data. Sedimentation rates ranged from 0.12% to 8.12% per decade, causing notable storage losses, such as 11.45 hm3 in Cruzeta over 81 years and 17.80 hm3 in Itans over 82 years. Reservoir lifespans were projected between 31 years and over 3,800 years, averaging 96 years. Sediment accumulation averaged 6.39 million tons, increasing evaporation losses and degrading water quality. The dense dam network (0.55 km2/reservoir) disrupts sediment connectivity, emphasizing the importance of conservation to mitigate soil degradation and maintain reservoir functionality. This study advances understanding of hydrosedimentological dynamics in arid and semiarid regions, underscoring the need for sustainable water resource management strategies.