Sediment deposition patterns in reservoirs with different water-level dynamics relevant for potential sediment reuse

Reservoirs are essential for water supply in dry regions. However, siltation reduces their capacity and degrades water quality due to adsorbed pollutants. Assessing the spatial pattern of sediment deposition in reservoirs is crucial for the adoption of mitigating measures. We analysed sediments from eleven reservoirs in the semiarid Jaguaribe Basin, Brazil, aiming at understanding the deposition patterns and sediment attributes required for exploring the possibilities for sediment reuse. We adopted an approach with four methodological steps: (1) correlation analysis to explore the associations between grain size distribution and nutrients content; (2) cluster analysis to identify typical types of texture distribution of deposited sediments; (3) frequency assessment of sediment submergence to quantify accessibility of sediments; and (4) development of a Reservoir Emptying Index (REI) to be used as a proxy of sediment deposition patterns. The results revealed a clear correlation between fine grains and nutrient concentrations. Reservoirs with high emptying frequency exhibited greater sediment mixing. Conversely, reservoirs with low emptying frequency demonstrated granulometric segregation, with sand deposited near the delta and finer grains close to the dam. We demonstrated that water level dynamics can be used to estimate sediment deposition pattern and that grain size distribution can serve as an indicator for selecting sediments suitable for applications such as soil amendment, environmental rehabilitation, and additives of building material for civil construction. Our findings enhance the understanding of the spatial and temporal availability of sediments in reservoirs, supporting strategies for their removal and reuse, thereby contributing to more efficient reservoir management.