Caracterização fisiográfica da bacia hidrográfica do rio Vacacaí na montante do ponto de captação de água de abastecimento de São Gabriel - RS

Abstract

This study aims to characterize the river basin upstream of the point in Vacacaí uptake of water supply of São Gabriel, Rio Grande do Sul and the methodology we used Geographic Information Systems ArcGIS 9.3 and Spring 5.1.8 , images from the Landsat 5 satellite, sensor TM, and maps of topography and drainage, to determine the parameters characterizing the basin. Regarding the use and occupation of land, most of the area (61%) is covered by natives pasture, followed by the other uses where the forest covers 14,3%, agricultural soil 24.5% and water 0.2%. The same has an area of approximately 113.062,59 ha, the perimeter of the basin comprises a length of 161.7 km, and the index value of 0.42 for the shape and compactness is around 1.44, corresponding to a bowl with elongated shape. This result demonstrates that the basin can be classified at low risk of flooding and flood. The drainage density obtained was 0.34 km ². The basin had an average slope of the watercourse of 7.36 m/km, which is considered low and the ordering of streams of the basin is 4th order.