Comparative study of standard and modified groundwater vulnerability methods in the gold and iron mining regions of Western Quadrilátero Ferrífero, Brazil

Abstract

This study aims to evaluate the intrinsic vulnerability of the Moeda Syncline, located in the western portion of the Quadrilátero Ferrífero in the State of Minas Gerais, Brazil. This region stands out for hosting important gold and iron ore mines and is the target of geological studies due to its structural complexity and economic importance. The Moeda Syncline is responsible for feeding springs and important tributaries in the hydrographic basins of the Velhas and Paraopeba rivers, thus contributing with a great part of the water consumed by the population of the Metropolitan Region of Belo Horizonte (RMBH). The main threats to the sustainable use of water in the Moeda Syncline are urban expansion and mining enterprises. From the mapping of vulnerability to contamination it is possible to identify the areas that need to receive priority treatment. To assess the vulnerability of aquifers, four methods were selected according to the types of aquifers, namely: DRASTIC, SINTACS, GOD and EPIK. The DRASTIC method was developed to be used in any type of aquifer, the SINTACS method was developed for fissural aquifers, the GOD method for porous aquifers and the EPIK method for karst aquifers. In addition to the application of the proposed methods, modifications were made in order to adapt the method to the physical characteristics of the region, considering the less efficient parameters. From the results obtained, it was found that the most appropriate method to assess the vulnerability of the study area are those specific to each type of aquifer, considering that the proposed adaptations proved to be more efficient than the original methods. In addition, it was observed that the DRASTIC method, developed for all types of aquifers, demonstrates efficacy by indicating that the main aquifers susceptible to contamination are those of the cover layers, Cauê and Gandarela.