Groundwater Recharge Through the Dolines in the Semi-Arid Climate in Minas Gerais State, Brazil

Localized recharge from dolines is very important, especially in arid and semi-arid regions, where it contributes to the groundwater recharge on karst aquifers. In areas with a shortage of water, these are the geomorphic structures where water runoffs occur and accumulate. The study area is located in sub-basins of the Rio Verde Grande, in Verdelândia and Varzelândia municipalities, and it displays features of the semi-arid climate (average annual regional rainfall of about 790 mm). The area is also characterized by the presence of dolines in the Neoproterozoic pelitic–carbonate rocks of the karst Bambuí Group. To understand the process of such a recharge and quantify it within the study area, automated identification in ArcGIS was applied in order to select two dolines. Also, the following methodological procedures were adopted: soil texture characterization; soil infiltration tests using Guelph and concentric double-ring infiltrometers; permeability tests; automated monitoring of rainfall and groundwater level; water balance estimated with the decendial water balance and water level variation methods. The results yielded local recharge values ranging from 57.7 to 122.2 mm/year (7.8–13.3% of the rainfall).