THE HAZARD OF POLLUTION AND THE VULNERABILITY OF THE AVERAGE AQUIFERO IN THE ARARIPE SEDIMENTARY BASIN
Vulnerability; sedimentary basin; GOD; Contamination; POS.
Most groundwater originates from excess rain that seeps into the soil surface. As a consequence, surface activities can threaten groundwater quality (FOSTER, et al 2002). The application of the vulnerability assessment methodology by the GOD method (FOSTER & HIRATA, 1988) in the medium aquifer in the Araripe sedimentary basin, Ceará - Brazil was developed in a GIS environment, as well as the modeling of contamination sources by the POSH method (FOSTER, et al 2002). The crossing of the natural vulnerability of the aquifer to potentially contaminating activities is called contamination hazard (FOSTER & HIRATA, 1988). The results of natural vulnerability modeling showed that most of the aquifer system was classified as having medium vulnerability (61.89%), followed by high vulnerability (16.74%) and low vulnerability (14.01%). When assessing the danger of contamination, the results are even more worrisome. The areas of high potential for contamination are linear following the bed of the main rivers in the region, aggravated by the lack of sanitation. The areas with a high risk of contamination are led by the municipality of Juazeiro do Norte with an area of 31.43 km², followed by Barbalha, with 20.24 km² and Missão Velha with 19.44 km². As for the danger of contamination in public supply wells, of the 359 wells, 26.74% were identified in areas of high and extreme danger, mainly in Juazeiro do Norte, thus, a significant portion of the region's population may consume water unfit for human consumption.