Transforming Drainage

Controlled Drainage Suitability Tool

This map identifies land in the Midwestern United States that has a high probability of being suitable for controlled drainage (CD), a practice also known as drainage water management.  The soils have been identified as likely to be drained for crop production, and relatively flat to maximize the spatial area controlled by each water control structure. 

Agricultural land was placed in five categories based on representative slope (<1%, 1-2%, or >2%) and the drainage class of the soils. “Poorly drained” is defined here as poorly drained or very poorly drained only. Somewhat poorly drained soils may be suitable but are less likely than the more poorly drained soils. Soils “not poorly drained” are moderately well, well drained, or excessively drained. The table below describes the suitability classification including those that are very likely to be suitable plus three classes of “potentially suitable”.

Suitability classification Explanation and limitations
Suitable for CD Poorly drained and slope < 1%
Potentially suitable 1 Potentially limited by drainage class: Somewhat poorly drained and slope <1%
Potentially suitable 2 Potentially limited by slope: Poorly drained and slope 1-2%
Potentially suitable 3 Potentially limited by drainage class and slope: Somewhat poorly drained and slope 1-2%
Not suitable for CD Limited by drainage class and slope: Not poorly drained or slope >2%

Limitations: This map is designed to give a broad picture of the locations in the region that are likely to be involved in CD activities to a greater extent.  The map does not take into account property boundaries and the fact that landowners and managers on neighboring properties may have different goals and objectives that may not include CD.  Also, areas that are not identified in this map may actually be suitable for CD, depending on the site-specific topography, drainage system layout, and other factors.  The map utilizes data that are intended for use at a broad scale, rather than a site-specific scale, so field verification of the suitability of any site is still needed when evaluating potential projects.

Data sources and acknowledgements: The tool was developed using the United States Department of Agriculture: 2018 gSSURGO data from the Natural Resources Conservation Service (USDA-NRCS) and the  2011 National Land Cover Database. The Hillshade Elevation layer was developed by  Darrell Schulze (https://soilexplorer.net). The CD Suitability map service layer is hosted by the Purdue University Libraries and School of Information Studies. This tool was developed by Ben Reinhart and Jane Frankenberger, Purdue University, 2025.

Citation for this online tool:
Reinhart, B. and Frankenberger, J., 2025. Controlled Drainage Suitability Tool. Transforming Drainage Tools, online at https://transformingdrainage.org/tools. [date of access]

Project Funding

This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2015-68007-23193, “Managing Water for Increased Resiliency of Drained Agricultural Landscapes.” Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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