Abstract:
Groundwater recharge represents a key component of the aquifer water balance, directly influencing
water resource availability, especially in regions where these resources are under intense pressure. The
Urucuia Aquifer System, located in western Bahia, plays a strategic role in supporting irrigated
agriculture, urban water supply, and the maintenance of ecosystems. However, the continuous expansion
of irrigated agriculture, combined with land use changes and climate change, has intensified
groundwater extraction, compromising aquifer recharge. In this context, this dissertation aims to
estimate the recharge of the Urucuia Aquifer System in an area located within the Corrente River basin,
using daily hydrometeorological data from five stations. Different soil water balance approaches were
applied, including deterministic, probabilistic, and stochastic methods, over an extended observation
period. The soil water balance modeling was based on the models developed by Porporato et al. (2004)
and Feng et al. (2015), allowing the evaluation of climatic variables such as precipitation,
evapotranspiration, and soil moisture on recharge formation. The results indicated that recharge is
concentrated during the rainy season and virtually absent during the dry period. Additionally, seasonal
precipitation patterns, characterized by variations in daily rainfall probability and mean precipitation
intensity, significantly influence recharge formation, with higher frequency and intensity of rainfall
during summer. A simple and robust empirical relationship was obtained, expressed as R ≈ P – 2,
indicating that annual recharge can be estimated from the precipitation surplus above a constant average
evapotranspiration threshold of approximately 2 mm/day. This approach proved more suitable than
fixed-percentage precipitation methods, as it better reflects the local hydrological dynamics. Simulations
show that reductions in precipitation may decrease recharge by over 30%, while soil moisture and
evapotranspiration remain stable due to the high soil water storage capacity and deep rooting systems.
The applied methodology proved effective in simulating recharge and supporting the management of
the Urucuia Aquifer, emphasizing the need for sustainable use in the face of agricultural expansion and
climate change.
