Water level alterations on the southern rim of the Guarani Aquifer due to the rain regime

Vanessa Da Conceição Osório,Cássio Stein Moura

doi:10.1590/2317-4889202120200079

Abstract

Abstract This paper estimated the total water storage variation in the southern rim of the Guarani Aquifer System during a three-year time span, making use of data provided by the Gravity Recovery and Climate Experiment. Monthly data were used to estimate the Bouguer anomaly in Southern Brazil. A direct modeling, using the Bouguer plateau, was applied to quantitatively estimate the water volume variation of a specific thickness in the studied region. Meteorological almanac data were compared to the gravitational alterations. We found a direct proportionality between the monthly rain average and the water table level. A simple model was found to forecast water accumulation as a function of rainfall regime, which is validated by a Pearson index of 0.82 that indicates a strong correlation between pluviometric and gravimetric data. In order to raise the stored water level near the recharge area by 1 mm, approximately 3 mm of rainfall is needed.

Highlights

Drought has become recurrent in the state of Rio Grande do Sul (RS), Southern Brazil, creating an environmental concern for the population
The Gravity Recovery and Climate Experiment (GRACE) consisted of two identical artificial satellites that were placed in the same polar orbit at approximately 500 km of altitude and separated by 220 km from each other
There is a low variation in the Bouguer anomaly corresponding to the coastal part of the continent, where the holocenic barrier deposits are located

Summary

Introduction

Drought has become recurrent in the state of Rio Grande do Sul (RS), Southern Brazil, creating an environmental concern for the population. The GAS is an important fresh groundwater reserve in South America, occupying part of the territories of Brazil, Argentina, Uruguay, and Paraguay. It comprises sandy lithologies representing the late Permian deposition of the Paraná Basin, ending up on the Eo-Cretaceous eolian sedimentation (Machado 2005). The state of Rio Grande do Sul is located over the southernmost part of the Aquifer, covering an area of 137 × 103 km. In Paraguay, the aquifer covers an area of 71.7 × 103 km, while in Argentina, 225.5 × 103 km; and in Uruguay, 58.5 × 103 km (Araújo et al 1995b)

Methods

Results

Conclusion