Obtaining of corrected DEM to watershed delimitation with the aid of free geotechnologies

Abstract

In Brazil, the National Water Resources Policy establishes that the basic unit of water resources management is the watershed. So the initial work, before the monitoring of the land use activities and the correlated ones, considering the basin, passes through the delimitation of its physiographic limits. Geotechnologies allow the interpretation of a set of data being possible the watershed delimitation modeling using free Geographic Information Systems (GIS) and free satellite images. However, the presence of dense vegetation promotes the generation of false peaks, leading to false modeling of flow segments, affecting directly the boundary basin modeling. This study aimed to correct the altimetry of a Digital Elevation Model (DEM) from Digital Surface Model (DSM) in order to delimit the watershed of Laranja Doce stream (Dourados/MS) with the aid of free software Quantum Gis (QGIS Development Team, 2015). As a result, it was observed that the DSM altimetric correction with the aid of photo-interpretation (Landsat 8 image, path/row 224/75, 2015) and field survey data, promoted a DEM model that represents accurately the relief and physiographic boundaries of the study area and can be used for future analyzes that require this information, as in morphometry and environmental monitoring.