This raster contains the natural, inherent, soil wetness of the lower 48 states, as determined by the ordinally based Natural Soil Drainage Index (DI). The DI is intended to reflect the amount of water that a soil can supply to growing plants under natural conditions. It ranges from 0 for the very driest soils and exposed bedrock, to 99 for areas of open water. Its derivation is based on soil taxonomic information, normally available in soil digital datasets. The index has many applications in the geosciences, forestry, ecology, geography, and environmental modeling, especially when examined spatially. The Drainage Index was developed by a partnership between Michigan State University and the U.S. Forest Service. DI values for all soils currently classified by the NRCS can be accessed from the DI web site: http://foresthealth.fs.usda.gov/soils.
Citation: Schaetzl, R.J., Krist, F.J. Jr., Stanley, K.E., and C.M. Hupy. 2009. The Natural Soil Drainage Index: An Ordinal Estimate of Long Term, Soil Wetness. Physical Geography 30:383-409.