Vulnerabilidade à contaminação intrínseca dos aquíferos da área urbana de Cuiabá e Várzea Grande - MT, Brasil

Abstract

Groundwater is essential for providing potable water to humanity. However, rapid urbanization and increased anthropogenic activities compromise the quality of aquifers, which are essential for domestic supply, irrigation, and various economic and social activities. To assess the vulnerability of aquifers in the urban areas of Cuiabá and Várzea Grande, Mato Grosso, Brazil, we used the GOD method, which allows a systematic approach to understanding the intrinsic characteristics of the aquifer and assessing its susceptibility to contamination. Using a public database of tube wells, the study evaluated vulnerability based on aquifer confinement, lithological composition of the unsaturated zone, and depth to water level, categorizing contamination vulnerability according to classes established by the GOD method. Results revealed a trend of shallow water tables, predominantly between 1.0 and 50 meters deep for the wells studied, indicating lower terrain relative to surrounding areas and increased susceptibility to contamination. The majority of wells exhibited medium to very high gravelly to clayey gravelly textures, suggesting high aquifer recharge potential but also posing elevated risks of groundwater contamination due to direct pollutant infiltration. The vulnerability index (GOD) for most wells ranged from moderate to high vulnerability, predominantly falling within the high vulnerability class. Generated GOD values were vectorized and interpolated across the study area, producing a vulnerability map indicating that Cuiabá, MT and Várzea Grande, MT exhibit areas of high aquifer vulnerability, with greater prevalence in Cuiabá, MT.