Study of water balance in Canoas river basin, Urubici, SC, Brazil: subsidy to protect the direct recharge zone of Guarani Aquifer System

Abstract

The Guarani Aquifer System (GAS) is considered one of the largest transboundary reservoir of groundwater in the world, however, the knowledge of the hydrogeological characteristics of the GAS is very incipient and irregular by the countries that cover it. In Brazil, the GAS is distributed by eight states, where some areas are reasonably well known, as in the states of São Paulo and Paraná, while in contrast in other states there is little or no information. This paper aimed to study the components of the surface water balance of the Canoas river basin in the city of Urubici, located in the Serra Geral of Santa Catarina, a direct recharge zone of the Guarani aquifer system - DRZ/GAS. The methodology proposed by UNESCO, described in the Guide for elaboration of water balance in South America, was used taking into account the following factors: rainfall, runoff and evapotranspiration. The storage of water in the basin is about 63.9 mm per year, and the months of July and January are most prone to water storage in the basin. The sub-basins of Cachimbo’s river and the Bugre’s river are the ones that most contribute to the overall water storage in the basin, with 170.6 mm and 91.6 mm respectively. The sub-basins of the Alto Canoas, Cachimbo’s river and Bugre’s river showed favorable conditions for direct recharge of the SAG.