MODELAGEM ESPACIAL DA VULNERABILIDADE À CONTAMINAÇÃO DAS ÁGUAS SUBTERRÂNEAS DESTINADAS AO CONSUMO HUMANO NO MUNICÍPIO DE BACABEIRA-MA.

Abstract

Groundwater resources have been subjected to various types of degradation, contamination and pollution, contributing to the environmental insalubrity and, consequently, to the proliferation of infectious and parasitic diseases, of water transmission. As such, water quality preservation is a need for universal responsibility and a challenge, which has been faced with monitoring strategies and the optimization of vulnerability mappings. However, the objective was to analyze the vulnerability to contamination of the groundwater of the municipality of Bacabeira, with a view to human consumption and consequently to the health of the population, through the spatial model in a Geographic Information System and physical-chemical analyzes (pH , chloride, nitrate) and bacteriological (total and thermotolerant coliforms). This municipality and its underground spring, already presents / displays a high susceptibility because it is exposed to factors of threat as inserted in coastal zone, to carry out mining activities, and recently to have created an industrial district in the area destined for the implantation of an oil and gas refinery. After reviewing the main existing methods and available spatial data, it is proposed as a model the Vulnerability Map using the GODD Method, adapted from the insertion of the Declivity parameter (D), the Confinement (G), Occurrence (O) And Distance (D). The data were extracted from the Underground Water Information System - SIAGAS / CPRM and EMBRAPA, SRTM Radar Digital Image Processing and fieldwork, which was carried out in April / 2016, the peak of the rainy season. The model (map) defined areas of extreme, high, medium and low vulnerability and allowed that the 10 wells that supply the communities in Bacabeira.When superimposed on the population data of the census tracts (IBGE), showed that 30% of the wells that directly supply 350 inhabitants are under high vulnerability aquifers, while 70% that respond for the supply of 450 inhabitants, revealed medium vulnerability to contamination. Regarding the physicochemical variables, only pH showed values within the permitted range, while chloride, nitrate, total coliforms and thermotolerant coliforms showed concentrations above the maximum permitted values, according to current legislation. In this way, the spatial modeling of vulnerability to contamination applied to underground water sources in the municipality of Bacabeira proved to be a tool capable of subsidizing decisions, as well as demonstrating that, in the groundwater quality scenario, the use of this source for human consumption presents as a potential risk factor for the health of the population exposed to waterborne diseases.