Comparison of Selected Methods for Estimating Groundwater Recharge In Humid Regions

Method:	Category:	Spatial Scale:	Temporal Scale:	Quantity Estimated:	Ease of Use:	Data Needs:	Cost:
Watershed Models	Streamflow	Watershed to Regional	Day to Years	Recharge	Moderate	High	High
Watershed-based rainfall-runoff models, such as PRMS can be used to estimate recharge for various temporal and spatial scales. Most watershed models require meteorological, land-cover, and soil-property, data as well as physical information about the watershed, such as altitude, slope, and aspect. Models are typically calibrated against streamflow records from a gaging station. Ground-water recharge is computed as the residual in the water-budget equation. Thus, errors in other water-budget terms can affect recharge estimates. Use of watershed models requires considerable expertise and costs are moderate to high. Numerous model codes are available.