The document discusses methods for estimating groundwater recharge using the WetSpass and MODFLOW models. WetSpass is a physically based model that uses inputs like land use, soil type, and climate data to calculate spatial patterns of evapotranspiration, surface runoff, and groundwater recharge. The recharge output from WetSpass is then used as input for the MODFLOW groundwater flow model. Together, WetSpass and MODFLOW allow for the simulation of spatially variable recharge and groundwater flow.