Análise do assoreamento do reservatório de promissão através do modelo RESSASS

Abstract

This paper presents the results of a study of sediment deposition at the Promissão city reservoir, located at Mid-Tietê river (São Paulo State, Brazil) where the generation of electric energy of the Mário Lopes Leão Hydroelectric Power Plant occurs. The quantification of reservoir siltation in the last thirty years of operation was accomplished by means of the comparison of the lake’s original topography in the reservoir filling period, in 1975, with the topobathymetry obtained in 2005. The module of “volume analysis” of the RESSASS model was used for the analysis of the reservoir volume variation during this period. The reduction of the total reservoir volume was of 3,73 % (considering the maximum operation level of 384,0 m) and of its useful volume was of 4,14 %, considering the operation levels of 379,7 m and 384,0 m. The reservoir siltation rate found for the analyzed period can be considered small and it must be caused mainly by the procedures of sediment dragging, for the exploration of materials for the civil construction. Nevertheless, studies of siltation analysis and updating of the curve stage VS. reservoir volume must be carried through so that reliable data regarding the current reservoir volumes may be offered