Analysis of groundwater age and flow fractions for source-sink assessments

ABSTRACT Capture zone analysis has been a prominent aspect in managing water supply wells. The study of aquifer vulnerability and protection also employs groundwater age modeling. Therefore, a comprehensive analysis of capture zones and groundwater age was used to propose a new method to understand the age fractions of water reaching pumping wells. The concept was derived from a volume-weighted approach for finding the mean age of a multi-component groundwater mixture. Numerical analysis of groundwater flow, age transport, and capture zone delineation was carried out to obtain volume-weighted mean groundwater age at the well. Thus, the groundwater age reaching a pumping well was easily assessed by computing age fractions. An additional recharge well rendered the groundwater age 25 days younger than that with a pumping well alone at 450 days. The example application described how the results could estimate the mean groundwater age at the sink point, contributed from the various sources.