Vulnerability to Groundwater Contamination of Fractured Aquifer in Itabaiana (SE)

Application of the GOD Method

Abstract

Currently in Brazil, even with the use of groundwater conditioned to compliance with various legal formalities that should ensure its quality and availability to users, there are still numerous illegal wells that hinder the management of groundwater and the understanding of its vulnerability as a natural resource. This study employs the GOD method with the aim of mapping, in a GIS environment, the natural vulnerability to contamination of the fractured aquifer in Itabaiana (Sergipe state), in the northeastern agreste region of Brazil. The method requires the analysis of three parameters: aquifer confinement (G); lithology and intensity of consolidation of the vadose zone or confining layers (O); and groundwater depth (D). Each parameter has weighted values from 0 to 1, analyzed based on available public data. After assigning the values, the vulnerability index is generated by multiplying the obtained parameters. The map of natural vulnerability of the fractured aquifer was produced using the inverse distance weighting (IDW) interpolation method employed in QGIS software. Itabaiana showed predominantly low vulnerability indices to contamination; however, regions with moderate vulnerability occur in isolated portions near large water bodies and require special attention from public agencies.