Interaction between surface and groundwater in the carbonate and mixed watersheds of the Lagoa Santa karst, Minas Gerais

Abstract

The Lagoa Santa karst, located near Belo Horizonte, Minas Gerais, contains significant carbonate and siliciclastic aquifers belonging to the Bambuí Group. To assist with management and monitoring, a network of streamflow monitoring stations was established in the main basins of the region. The monitoring aimed to study the evolution and general behavior of the basins over four complete hydrogeological cycles, from 2017 to 2021, and their relationships between surface and groundwater, to inform various studies, including those involving aquifer recharge. Key curves for representative sections were generated by correlating measured flow rates with water level data, and hydrographs were produced using water level data obtained semi-automatically from pressure transducers. The results revealed a general increase in the base level of the basins, with long recession periods suggesting a reactivation of upper conduits from 2019/20 and a slow discharge in various basins of the region, characteristic of a complex karst system with vertical and horizontal compartmentalization. Additionally, the high productivity of the Escrivânia-Gordura and Palmeira-Jaguara karst basins indicates the occurrence of allocthonous recharge.

Keywords: Lagoa Santa Karst; River Monitoring; Key curves