Using gis techniques to assess fractured aquifers vulnerability to contamination: São Domingos River Basin - São José de Ubá, Rio de Janeiro State, Brazil

Abstract

The São Domingos River Basin (SDRB), located in São José de Ubá, a city in the Northwest Region of the state of Rio de Janeiro, is one of the state portions situated in crystalline terrains, which are periodically affected by the shortage of surface water resources. The purpose of this research, to define a general vulnerability model for fractured aquifers, was based on the necessity to protect the groundwater resources of the SDRB. SDRB presents features, such as dependence on groundwater water resources in a crystalline substrate and severe recurrent droughts, which make it suitable for the study goals. The methodology used to assess the vulnerability encompassed the following variants: density of structural lineaments, aquifer lithology, declivity, recharge and depth of the top of the aquifer. These variants were pondered per their influence on the vulnerability, considering a multicriteria analysis, and incorporated into the Geographic Database (GDB). The Geographical Information System (GIS) proved to be a useful tool to calculate the vulnerability classes. The results indicate that the method used was adequate to assess the vulnerability of the fractured aquifers of SDBR, which could be used in regions that present similar physiographic aspects as it indicates tendencies close to field reality. The predominant vulnerability classes in the SDBR vary from moderate to high, indicating a fragility of the fractured aquifers systems in the region, which require usage planning and adequate management of the resources.

Keywords

• Vulnerabilidade. Aquíferos Fraturados. Bacia Hidrográfica do Rio São Domingos. Sistemas de Informação Geográfica.