A framework model to prioritize groundwater management actions based on the concept of dominant risk: An application to the state of Espírito Santo, Brazil

The objective of this study was to assess the risk of groundwater contamination in the state of Espírito Santo (Brazil), with a focus on the city of Vitória (the state capital), based on the so-called “Vulnerability versus Hazard” method. This method consists in assessing the risk of groundwater contamination using as base data the intrinsics's aquifer vulnerability and the main human activities as proxies of hazards. The assessment based on this approach results in a quadrant system that links different levels of risk to different management priorities, allowing the implementation of mitigating actions according to the identified level of risk. In this study, the method was adapted to identify a dominant risk, which was the most impacting among the hazards related with industrial, infrastructure or agricultural activities. The results showed a dominant risk map with significant levels classified as high and moderate in the northern regions and along the coast of Espírito Santo state, due to the concentration of various human activities. In the Vitória's metropolitan and southern regions of the state, the risk of contamination was lower, due to the characteristics of soil and the presence of fractured aquifers that act as natural barriers. However, there were exceptions, such as between Alegre and Castelo areas, which indicated incidental threats to public health due to human activities. The analysis of Vitória municipality showed 46.9 % of the area at very low risk, 5.5 % at low risk, 35 % at medium risk and 12.6 % at high risk. It is noteworthy that 47.6 % of this municipality is already at a moderate or high-risk level, highlighting significant environmental challenges around the Santa Maria River, the Vitória airport area and the Camburi beach. Overall, the study of groundwater contamination risk in the state of Espírito Santo revealed a challenging scenario, highlighting the urgency of effective actions to promote environmental resilience in Vitória. • We set a dominant groundwater contamination risk from urbanization, agriculture or industry. • We assessed the risk across the Espirito Santo state (Brazil) and zoom it at the capital Vitória city. • Significant contamination risks occur in the northern and coastal regions of the state. • The significant risks relate with mining and the exploitation of land and sea resources. • In Vitória city, the major risks were mapped at the airport area and Camburi beach.