Utilizing unsaturated soil zone models for assessing managed aquifer recharge

Managed aquifer recharge (MAR) is increasingly used to balance out the divergence between natural groundwater recharge and overexploitation of groundwater resources. As testing and design of recharge facilities can be cost and time-intensive, modeling tools hold great potential to design field investigations as well as to augment and extrapolate from their results. Focusing on unsaturated soil zone models, this study first reviews 16 previous modeling studies showing their range of model types and applications. The review is accompanied by an example of the use of HYDRUS 2D/3D, an unsaturated zone model, to design a novel small-scale infiltration basin. The basin is going to be established as part of a field and laboratory research facility for MAR in Pirna, Germany. Modeling results assisted in determining the dimensions of the infiltration unit as well as the placement of measurement devices and experimental scenario planning. Finally, the strengths and constraints of this modeling approach for MAR assessment are discussed.