This map identifies agricultural areas that are likely to have been drained for crop production, usually through subsurface tile drainage, in the Midwestern United States. These areas were identified based on the natural drainage condition of the soil, using the 2018 gSSURGO data from the USDA Natural Resources Conservation Service. Only agricultural land is included, based on the 2011 National Land Cover Database.
- Very poorly to poorly drained soils are assumed to have at least some form of artificial drainage installed to support agricultural land use, and therefore classified as "likely to be drained".
- Somewhat poorly drained soils are classified as "potentially drained", as these soils are often included whenever drainage improvements or upgrades are made in the field.
- Moderately well drained to excessively drained soils are classified as "unlikely to be drained" as these soils are not likely to suffer from excess soil water conditions, and therefore not likely to be artificially drained.
Field assessment is needed when determining the actual drained conditions of a particular area of interest.
The Hillshade and Natural Drainage Class layer services were developed by Darrell Schulze (https://soilexplorer.net). The map service is hosted by the Purdue University Libraries and School of Information Studies.