Hydrodynamic behavior and groundwater recharge in a Quaternary Coastal Aquifer in Sergipe: A seasonal analysis (2023-2024) from SEHRES

Abstract

This study analyzed the hydrodynamics and recharge of the shallow aquifer at the Sergipe Hydrogeological Research Site (SEHRES), based on systematic groundwater level monitoring conducted between 2023 and 2024. The objective was to understand the aquifer’s response to seasonal variations and to estimate groundwater recharge using the Water Table Fluctuation (WTF) method, adopting a conservative specific yield (Sy) of 10%. SEHRES, located on the campus of the Federal University of Sergipe in São Cristóvão, encompasses an unconfined and sandy Quaternary Aquifer System (SAQ), characterized by high hydraulic connectivity and dynamic interaction with the Poxim River. Weekly monitoring of 15 observation wells, combined with daily rainfall data, allowed the characterization of seasonal groundwater level variation and the estimation of net recharge. Results revealed typical patterns of recharge during the rainy season (April to July) and gradual drawdown during the dry season. The average estimated recharge increased from 132.8 mm in 2023 to 160.7 mm in 2024. The proportion of rainfall converted to recharge rose from 10.4% to 11.0%, reflecting improved infiltration efficiency. Potentiometric maps indicated a predominant groundwater flow from west to east/southeast, toward the Poxim River. Spatial analysis revealed significant variation among wells, associated with lithological differences and land use. This study provides valuable insights into the hydrological dynamics of tropical coastal aquifers and contributes to the development of sustainable groundwater management strategies.