Analysis of Morphometric Variables of River Espinharas Hydrographic Sub-basin Using Geographic Information System

Abstract

The relief forms, terrain differences, soil type and flora are the most important indicators for the description of a river basin or drainage network. The present work had as objectives, to perform the morphometric characterization of the hidrographic sub-basin (SBH) of the Espinharas river; analyze the intensity of land use; suggesting mitigating measures in areas with greater intensity of use, with the help of geospatial tools. The sub-basin of the Espinharas river, extends through thirty-one (31) municipalities, covering the states of Paraíba, Rio Grande do Norte and Pernambuco. For the analysis, images were used, from the Digital Elevation Model (DEM), Shuttle Radar Topographic Mission (SRTM), and Landsat 8 satellite images, resolution 30 m, bands 2, 3 and 4. Next, with QGIS software aid 2.18.17 generated the map of slope, mapping of intensity and land use, later calculations of the morphometric variables, and finally elaborated proposals of mitigating measures for the degradation of the sub-basin. The results of the morphometric parameters found for the Sub-basin indicate values of the Compass coefficient of 2.68 and Form factor 0.32, indicating that the sub-basin presents an irregular shape that differs from the figure of a circle, approaching an elongated shape, and thus not conducive to flooding. In relation to the intensity of use, the areas with low intensity class of use have the largest representation in this basin, covering an area of 2,147.98 km² (65.27%). The Espinharas river sub-basin presents several nonconformities of environmental impacts generated mainly by bad planning of use of the area and disrespect to the legislation. In this case, it is necessary for research to support effective public policies that favor less impacting agricultural practices, allowing farmers to provide their livelihoods at the same time, allowing future generations to survive in the semi-arid.