Techniques and Methods 6–A31
Groundwater Resources Program
SWB—A Modified Thornthwaite-Mather Soil-Water-Balance Code for Estimating Groundwater Recharge
Chapter 31 of
Section A, Groundwater, of
Book 6, Modeling Techniques
By S.M. Westenbroek, V.A. Kelson,1 W.R. Dripps,2 R.J. Hunt, and K.R. Bradbury3
1Wittman Hydro Planning Associates, Bloomington, Indiana
2Furman University, Greenville, South Carolina
3Wisconsin Geologic and Natural History Survey, Madison, Wisconsin
A Soil-Water-Balance (SWB) computer code has been developed to calculate spatial and temporal variations in groundwater recharge. The SWB model calculates recharge by use of commonly available geographic information system (GIS) data layers in combination with tabular climatological data. The code is based on a modified Thornthwaite-Mather soil-water-balance approach, with components of the soil-water balance calculated at a daily timestep. Recharge calculations are made on a rectangular grid of computational elements that may be easily imported into a regional groundwater-flow model. Recharge estimates calculated by the code may be output as daily, monthly, or annual values.
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Westenbroek, S.M., Kelson, V.A., Dripps, W.R., Hunt, R.J., and Bradbury,K.R., 2010, SWB—A modified Thornthwaite-Mather Soil-Water-Balance code for estimating groundwater recharge: U.S. Geological Survey Techniques and Methods 6–A31, 60 p.
Use of the SWB Model
Summary and Conclusions
Appendix 1: SWB Module Description
Appendix 2: Preparation of Gridded Climatological Data for SWB