Project Number:
DNR-150
Other Project Number:
WR99R018
Funding Year:
1999
Contract Period:
Funding Source:
DNR
Investigator(s) and affiliations:
Weston Dripps, University of Wisconsin–Madison;
Chip Hankley, Wisconsin Geological and Natural History Survey;
Mary P. Anderson, University of Wisconsin–Madison;
Kenneth W. Potter, University of Wisconsin–Madison
Abstract:
Abstract: Understanding the spatial distribution of groundwater recharge is a basic prerequisite for effective groundwater resource management and modeling. Recharge, defined as entry of water into the saturated zone, depends on a wide variety of spatially variable parameters including the vegetation, soils, topography, and climate. Its dependence on these variable parameters makes it one of the most difficult and uncertain hydrologic components to quantify in the evaluation of groundwater resources. Although many researchers have proposed techniques for estimating groundwater recharge, only a few studies have considered its spatial variability, and still no standard accepted method exists to quantify recharge for regional groundwater studies.
We have developed a simple soil-water balance model to estimate the annual spatial distribution of groundwater recharge for watersheds in humid areas. The model is based on a modified Thornthwaite — Mather approach (1957) and uses typically available soil, land cover, topographic, and climatic data. The model does not require extensive parameterization, can be practically applied in a relatively short time frame, and is easy to use. The model code is written in Visual Basic and requires Microsoft Excel 2000 to run. ArcView and ARCINFO are used to generate the model input grids.
The model was applied to the Pheasant Branch Creek watershed of south central Wisconsin where the United States Geological Survey (U.S.G.S.) recently completed a groundwater flow model and a calibrated water balance model (PRMS, Leavesley et al., 1983; Steuer, 1999; Hunt and Steuer, 2000). Our model compares reasonably well with the USGS models, and, in most instances, provides similar spatial recharge arrays for the watershed and comparable estimates of groundwater recharge. Our new model presents modelers, planners, and policy makers with a practical tool for providing recharge estimates for modeling and water resource planning purposes.