Influência das mudanças no uso e cobertura do solo na dinâmica do escoamento superficial na Bacia do Capivari - BA

Abstract

The objective of this study was evaluate the influence of land use and cover on the surface runoff dynamics of the Capivari Basin, aiming to provide subsidies for the planning and management of the region's water resources. In order to reach the proposed goal, the analysis of the changes in the land use and cover of the Capivari Basin was made, based on satellite images of the Landsat series for the years 1973, 1994, 2000, 2003, 2014 and 2017 available on the website of INPE and USGS. The images were submitted to classification of use and coverage, in the SPRING software, using segmentation and the Bhattacharya classifier. The morphometric characterization was done in Quantum GIS software, using the ALOS/PALSAR DEM of 12.5m. The runoff was determined from the CN method and modeling in GIS environment. From the results, it was possible to conclude that the Capivari River Basin is not prone to flooding, but it is believed that the predominance of high declivity in the drainage areas, together with the lack of riparian vegetation, favors an increase in vulnerability to erosion. The natural vegetation is scarce in most of the basin, which presents adequate vegetation only in the areas close to the mouth, being noticeable the direct impact of the changes of use and cover in the maintenance of the water flow of the river. The higher precipitation rates, the soil characteristics and the greater declivity in the river mouth, influenced the greater vulnerability to the runoff, according to the proposed model, but the most conserved PPAs have been effective in maintaining the perenniality of the Capivari River in these areas. The areas considered most critical in relation to the risk of water erosion for 2017 were those of the medium Capivari, since they presented high rainfall in certain months, but did not present PPAs in the areas of riparian forest or in the tops of the hill, which also increase the vulnerability of these areas to erosion. Finally, it is believed that the proposed model presented good results allowing the determination of the most susceptible areas to the runoff inside the Capivari Basin.