Application of the WTF method for estimating groundwater recharge in the Quaternary Aquifer System in Sergipe State, Brazil

Abstract

This unprecedented study of underground recharge in Sergipe aims to estimate recharge rates in the Quaternary Aquifer System in the year 2023 using the Water Table Fluctuation (WTF) method, based on piezometric data from wells of the SEHRES (Sergipe Hydrogeological Research Site), Federal University of Sergipe, Campus in São Cristóvão/SE. The field methodology adopted involves weekly monitoring of groundwater levels in 15 tubular wells using a millimeter-precision electric water level meter, from March to December 2023. Hydraulic heads of the wells were measured during dry and rainy seasons, used for the application of the WTF method. The results reflect minimum recharge rates on the order of 14% (132.8 mm) and maximum of 28% (256.6 mm), considering the total accumulated precipitation of 949.60 mm obtained at the CEMADEN station during the monitored period and estimated Sy between 10% and 20%. This range of values, although preliminary, is plausible considering the hydrogeological and climatic context of the region. Wells in the central and southwest portion showed higher recharge rates, and overall, recharge decreases towards the Poxim River, the main discharge zone of the aquifer. The results obtained in this work, albeit punctual, fill a gap in knowledge in the regional scientific literature. Furthermore, recharge rate estimates are fundamental to support effective strategies for planning the use and conservation of water resources; consequently, advancing knowledge in SEHRES will subsidize short- and long-term water management plans.