Is it really necessary to use complex methods for silting estimation in reservoirs?

É realmente necessário usar métodos complexos para estimar o assoreamento em reservatórios?

The study aimed to evaluate whether primary hydrosedimentometric monitoring data would be sufficient to estimate the total siltation of the Pimental Reservoir (Belo Monte HPP) or whether more complex methods would be required. Three mass balance approaches were applied: the sedimentometric method, the simplified Sediment model, and three-dimensional hydrodynamic and sediment transport modeling (Delft3D). The three-dimensional model was calibrated and the silting was evaluated for a period were observed data was available. Subsequently, a future scenario (2018–2039) was simulated based on extrapolations of existing flood hydrographs and operational data. The results showed similar average siltation rates between the sedimentometric method (1.37 hm³/year) and the 3D modeling (1.31–1.48 hm³/year), while the Sediment model overestimated siltation rates (2.29 hm³/year) because it did not represent the outflow through the diversion channel. When evaluating sedimentation rates over decades, an increase in rates was observed in the second decade for all methods. It was observed that less complex methods can provide representative estimates for siltation management, provided there is adequate monitoring, especially in the diversion channel, and monitoring during flood peaks.

Keywords:
Reservoir; Three-dimensional modelling; Mass balance; Silting rate