Determinação da produção de sedimentos em bacias hidrográficas de regiões tropicais

Abstract

This study aimed to determine the average annual amount of sediment produced in the sub-basins of the Umbeluzi river basin, defined as the percentage of eroded sediments reaching the river mouth, and to evaluate the cause-effect relationships between average annual erosion and the factors involved in this process. Average annual soil erosion soil erosion, laminar and furrow erosion, was quantified using the Revised Universal Soil Loss Equation Soil Loss Equation (EURPS), using the QGIS software applied to geographical information geographic information systems. The application of EURPS requires knowledge of the spatial distribution of of the factors R (rainfall erosivity), K (soil erodibility), LS (topographic factor) LS (topographic factor), C (land use and land cover) and P (soil conservation practices factor). The average annual erosion in the Umbeluzi basin varied from 0 to 2157.62 Mg/ha/year. 98% of the area presented erosion values lower than 41 Mg/ha/year and around 86% with values lower than 5 Mg/ha/year, which is justified by the predominance of percentage of the basin occupied by dense and low vegetation, with few agricultural There are few agricultural areas and even fewer built areas; classes of use that are more prone to erosion. A basin was subdivided into 8 sub-basins according to the drainage structure prevailing drainage structure and sediment yield was calculated from values of the sediment delivery rate sediment delivery rate (TES) and gross erosion of each sub-basin, having obtained values of sediment production between 30 668.4 and 99 541.3 Mg/year. It was concluded Thus, it was concluded that the sub-basins present low to moderate values of erosion. (Traduçao nossa)