Aplicação de métodos de determinação da descarga de sedimentos no Ribeirão Jordão para uso na estimativa do assoreamento de reservatório

Abstract

Reservoirs formed by dams are bound to the silting process, which is the accumulation of sediments at the bottom of a watercourse, that causes the reservoir useful volume to be reduced. Sediment transport and deposition along with erosion are responsible for the silting process. The purpose of this work is to present results of the evaluation of sediment transportation in the Jordan River, which is located near the city of Araguari-MG, in the Triângulo Mineiro. Geological data collection campaigns, runoff parameters and bottom sediment samples were carried out throughout 2018, at four points along the river. During this period, sieving tests of the bottom material and determination of the concentration of suspended sediments were carried out in the laboratory, providing data for the application of different methods of indirect estimation of solid sediment discharge. Nine methods of calculation were used: Ackers and White method (1973); Bishop, Simons and Richardson (1965); Cheng (2002); Colby (1957); Einstein and Brown (1950); Engelund and Hansen (1967); Karim (1998); Shen and Hung (1971); Toffaleti (1969). From these methods it was possible to establish a relationship between the sediment transport with the rainy periods in the region and with the erosive processes observed in the field. Taking into account the silting process, one can also evaluate the most favorable section for the construction of a reservoir. The work also presents the determination of a key curve for each section of the points studied, the flows were measured through the Accoustic Doppler Current Profiler (ADCP) and the fluviometric reel. The determination of the key curve occurred only for didactic reasons, due to the lack of data, for an acceptable precision.