When using groundwater flow models to simulate groundwater availability in regional aquifers, it is essential to consider how changes in land management practices have influenced model parameters with time. Model parameters subject to variability with land management change include recharge, evapotranspiration, and potentially the location and rates of natural discharge. Changes in model parameters due to land management changes may be intentional, or unintentional. Case studies will be shown of how recharge can change because of construction of impervious structures, changes in agricultural practices, large-scale irrigation or drainage, and afforestation or deforestation. Models can be used to predict the impacts of changing land management and to design mitigation features. As a result of these types of models, rain gardens have been designed to recharge water from stormwater at the point of generation. Also, models have been used to predict how fire management will influence recharge in forested catchments. Regional groundwater availability models must incorporate these land management changes to be effective.