Adaptação metodológica para delimitação de áreas estratégicas de gestão dos recursos hídricos subterrâneos : estudo de caso da Bacia do Pratagy

Abstract

Groundwater plays an important role in environmental processes, as well as being an alternative source of water supply for many Brazilian cities. The excessive use of this resource simultaneously with activities of high polluting potential in vulnerable areas can contribute to the degradation of the aquifer. Therefore, the present work aims to analyze the spatial dynamics in the Pratagy River watershed, building vegetation index and mapping the land use, as well as delimiting Strategic Management Areas considering the conservation, use and maintenance of the availability of water resources in a hydrographic basin. For this, images from the Landsat 5 satellite, Thematic Mapper (TM) sensor, from the years 1998 and 2011, were processed, using the QGIS 3.16.11 software to apply Remote Sensing and Geoprocessing techniques directed to the study. To evaluate the spatio-temporal behavior of the basin region, the Normalized Difference Vegetation Index (NDVI) and the Soil-Adjusted Vegetation Index (SAVI) were applied, and the Unsupervised Classification was used in the images obtained. For comparison purposes, they were classified into four classes, named: water, urban area/exposed soil, sugarcane/pasture and dense vegetation. As the images analyzed corresponded to only two different years, it was not possible to indicate a behavior in the study region. Even though it is not possible to carry out the analysis of the space-time dynamics, it is possible to see that in all circumstances, the areas destined for sugarcane cultivation and for pasture present expressive values. To determine the strategic areas for the use and conservation of groundwater resources, the methodology proposed by OHUFIJI (2020) was used, in which it uses the integration of the environmental characteristics of the basin. The themes used were underground recharge potential, geology, soil, slope, underground wells location and land use. Four Strategic Management Areas were defined: Strategic Area I (Immediate Protection), Strategic Area II (Restriction and Control), Strategic Area III (Prevention) and Strategic Area IV (Protection of Wells for Domestic Supply). The present study seeks to contribute with elements for future actions of management, monitoring and integrated conservation of water resources.