Estimating aquifer recharge in plains environments based on groundwater level variations

Groundwater recharge estimation is one of the major unknowns when generating both conceptual and numerical hydrogeological models. Aquifer recharge refers to water that crosses the lower limit of the non-saturated zone, reaches the aquifer and produces measureable increases in the water table level. Though several techniques currently exist to quantify this, selecting that which is most appropriate is often difficult, especially because of the need to consider the spatial-time variation, range and data reliability of each methodology. The main objective of this study is to estimate the recharge value in the unconfined detritic aquifer in the southeast province of Buenos Aires known as the Bonaire Intermountain Plains Region, using the water table fluctuation method. A northwestern portion of the intermountain plains of this province was selected as a pilot area. The results provided a total recharge value ranging from 14.4 to 18.7% of the total rainfall. This study also presents monthly recharge data and maximum specific yield values, the latter with values between 9.9 and 13.6%.