Evaluation of physical characteristics of Pariquera-Açu River watershed in Low Ribeira de Iguape Valley, Sao Paulo State, Brazil

Abstract

The morphometric characteristics of watersheds are essential elements for the assessment of hydrological behavior and its relationship with the maximization or minimization of environmental impacts. Thus, the aim of this study was to analyze the morphometry of Pariquera-Açu River watershed in low Ribeira de Iguape Valley in Sao Paulo State, Brazil with the use of geoprocessing technical, in order to obtain information that provides subsidies for the planning and management of this area regarding preservation. The basin covers an area of 345.27 km² and its main economic activities comes from the tea and banana cultivation. The contours were extracted from the Digital Terrain Model (DTM) of the Japanese satellite Alos and the hydrography of the topographic maps of the Geographic and Cartographic Institute (GCI) to determine the morphometric indices. The results demonstrated that the median values of drainage density associated to the presence of lowland areas and low roughness coefficient, facilitate the infiltration of water into the soil, decreasing runoff as well as the risk of erosion and environmental degradation and provides agricultural development. The low values of the circularity index and the compactness coefficient indicate that the basin tends to be elongated with less susceptibility to the occurrence of accentuated floods. However, due to the flat relief in the areas close to the water courses episodes of flooding may occur. Therefore, these areas should receive special attention from public managers regarding monitoring and conservation actions.