FLUVIAL DEPOSITION PROCESS IN COMPRIDA BAY, PARAGUAY RIVER, MUNICIPALITY OF CACERES--MATO GROSSO, BRAZIL/ PROCESSO DE DEPOSICAO FLUVIAL NA BAIA COMPRIDA, RIO PARAGUAI, MUNICIPIO DE CACERES--MATO GROSSO, BRASIL

In this work we evaluated the granulometric characteristics of sediments deposited in the fluvial space of Paraguay River--the Comprida Bay--which were interpreted according to the dynamics of the main channel. The hydrodynamic data was obtained with the service of the echo sounding and the fluviatile reel. To determine the granulometric composition, the material was subjected to physical analysis with the pipetting and screening methods. The flow values recorded during periods of drought and full ranged from 62.28 [m.sup.3]. [sup.s-1] and 0.71 [m.sup.3]. [s.sup.-1] at the entrance of the channel and 56.61 [m.sup.3]. [s.sup.-1] in the output of the channel for the full period. Concerning to the depth, it was registered the maximum 2.72 m and not less than 0.10 m. The results showed predominance of sands, which resulted in silting up the channel with sediment bars. This fact can be explained because, during the full, sediment transfer occurs with predominance of medium sand and fine sand of the main channel of the Paraguay River to the Comprida Bay. The study is relevant to understand the changes in terms of storage and deposition of sediment in Comprida Bay on the Paraguay River in distinct periods of full and drought. Keywords: Hydraulic variables, granulometry, secondary channel. Neste trabalho foram avaliadas as caracteristicas granulometricas dos sedimentos depositados em ambiente fluvial do rio Paraguai--a baia Comprida--e interpretadas por intermedio da dinamica do canal principal. Os dados hidrodinamicos foram obtidos com auxilio de ecobatimetro e molinete fluviometrico. Para determinacao da composicao granulometrica, o material foi submetido a analise fisica com os Metodos de Pipetagem e Peneiramento. Os valores de vazao registrados nos periodos de estiagem e cheia variaram entre 62,28 [m.sup.3]. [s.sup.-1] e 0,71 [m.sup.3]. [s.sup.-1] na entrada do canal da baia Comprida e de 56,61 [m.sup.3]. [s.sup.-1] na saida do canal da baia Comprida para o periodo de cheia. Com relacao a profundidade, registrou-se maxima de 2,72 m e minima de 0,10 m. Os resultados mostraram predominancia de areias, o que resultou em assoreamento do canal com barras de sedimentos. Esse fato pode ser explicado porque, durante a cheia, ocorre transferencia de sedimentos com predominancia de areias medias e areias finas do canal principal do rio Paraguai para a baia Comprida. O estudo mostrou-se relevante para compreensao de mudancas em termos de armazenagem e deposicao de sedime