Groundwater contamination hazard in the Indaiatuba to Capivari region, State of São Paulo, Brazil

Abstract

The mapping of groundwater contamination hazard is a helpful tool for planning land use, identifying priorities for controlling human activities and for protecting groundwater sources. Considering hazard as a result of the interaction between the aquifer natural vulnerability and the potential contaminant load imposed by human activities, in this study, the classification system for groundwater contamination hazard was adapted to allow mapping based on spatial analysis techniques in GIS (Geographic Information System). The groundwater contamination hazard was mapped in an area comprised by six cities, which are located in the eastern part of São Paulo State, Brazil, and experienced significant economic development and accelerated urban expansion. The groundwater contamination hazard map associated with point sources of contamination indicated that critical areas are located in the industrial districts of Indaiatuba and Salto and are scattered along the Capivari River and highways. In urban areas, the risk of contamination associated to leakage of sewage systems is concentrated in older parts of the city with high density of occupation. In rural areas, the risk of contamination is high or moderate mainly in the western portion of the study area, which is dominated by sugarcane monoculture. With regard to diffuse contamination sources, there is a predominance of areas with moderate to very low contamination hazard resulting from the low aquifer vulnerability in the region. Considering the dynamics of land use, the groundwater contamination hazard map must be regularly updated to better support groundwater management and land use planning and geoprocessing tools can facilitate this task.