Pantanal de Cáceres: composição granulométrica dos sedimentos de fundo no rio Paraguai entre a foz do rio Cabaçal e a cidade de Cáceres, Mato Grosso, Brasil

Abstract

The objective of the study was to verify the granulometric composition of bottom sediments along the longitudinal profile of the Paraguay River between the outfall of the Cabacal River and the city of Caceres, Mato Grosso, comprised by the geographic coordinates 15o58'00'' and 16o50'00'' South Latitude and 57o40'00'' and 57o44'00'' West Longitude. Work activity was conducted to characterize the sites and sediments collection with Van Veen sediment sampler (seven samples); textural analysis of the sediments by the pipetting and sieving method (the method uses a combination of sieving and sedimentation). The Paraguay River exhibits a meandering style with two distinct periods (periodic flooding regime and drought) that associated with of bottom sediments alternate processes of erosion, transport and deposition from the discernible changes in the complex landscaping. Thus, the concentration of sand in the bed load transported in the channel (five samples) is related to environmental elements and land use. The fine sediments are transferred to the features (bays and ponds) and flood plain; the intense fluvial dynamics and the course (alluvial deposition areas) contribute to changes in channel and morphologic features (capacity transport and sediment depositions).