Environmental scientists and local planners need a way to estimate initially the impacts of land-use change on groundwater recharge, water supply and wetland hydrology. Using a core component of more complex models, a simple spreadsheet analysis can estimate the change in runoff and recharge from past or proposed land-use changes. This day-to-day tool for planners uses only readily available data. In a sample analysis, conversion of woodland to high-density residential and commercial uses causes an eleven- to nineteen-fold increase in run-off volumes, and loss of 11 to 100 percent of the natural groundwater recharge. A survey of planners found enthusiasm for the model. Potential applications are plan review, raising community awareness of potential problems and support for regulatory action, and as part of local guidelines to minimize disturbance of the hydrologic regime.
