Recarga do tipo Localizada em Ambiente Semiárido: estudo de Caso em Dolinas da Bacia do rio Verde Grande, Minas Gerais

Abstract

The localized recharge from sinkholes in arid and semiarid regions assumes importance in the recharge of karst-fractured aquifers, since these geomorphological structures favor the concentration of runoff water. The study area, sub-basins of the Verde Grande River in the cities of Verdelândia and Varzelândia , falls within the semiarid climate (790 mm/year) , being strongly marked by the presence of sinkholes installed in the Neoproterozoic carbonate-pelitic sequence of the Bambuí Group. In order to understand the processes of this type of recharge and quantify it in the study, two sinkholes were selected in the area from the automated identification in ArcGIS , in which the following methodological route was taken: textural characterization of soil field and grain size in laboratory; testing of soil infiltration by Guelph permeameter methods, double ring infiltrometers; evaluation by slug test of permeability of aquitard/aquiclude from the bottom of the sinkhole; automated monitoring of rainfall and water level; hidric balance and estimated recharge by the water balance and water level variation methods. Data analysis involved the statistical analysis of Cross-Correlation Function between the data of rainfall and groundwater level from the bottom of sinkholes. The results indicate recharge values between 8% and 13% from precipitation and allow us to infer its important role in aquifer recharge of localized type.