Geoelectrical model for aquifer in the bonita lake region, Planaltina, Distrito federal, Brazil

Abstract

The aim of this study was to analyze the soil geoelectric behavior, through geophysical surveys, in the surrounding region to Bonita Lake, a natural reservoir located in the Ecological Station águas Emendadas (ESECAE), 50 kilometers from Brasília (Brazil). Sixteen vertical electrical sounding (VES) were performed with Schlumberger array. The geoelectrical model, obtained by inversion of the field data and statistical analysis of the inverted data, indicated structure with superficial dry soil above partially saturated layer, and finally a soil or rock with low permeability, related to the aquifer formation with varying thickness, about ten meters below the lake and up to twenty meters deep in the surrounding area. The VES showed that the aquifer has great lateral extension to the north, east and west of the lake; providing water to the same, while in the south, the aquifer is possibly limited by quartzites of the Canastra Group. This restriction can result in the absence of aquifer recharge in the southern portion, and coincides with the region where the lake drains into the source of Mestre D’Armas stream. This information is important because it can be used in the delineation of the hydrogeological basin and the Bonita Lake protection perimeter.