Poorly drained and hydric soils are common in these depressions, and to enable cropping of areas subject to surface ponding, drainage has often been improved by installing surface drains (or intakes) as part of in-field tile drainage systems. Conservation practices that may be appropriate in depressions can include filter practices to treat water entering the tile intakes, with impacts on drainage rate that are acceptable. There are several types of intake filter practices including blind (sand-bed) intakes and grass buffers. Wetland restorations may also be feasible where soil wetness in depressions is frequently problematic for crop production. The potential benefits of these practices include reduced sediment and phosphorus loads, and water storage. See Smith and Livingston (2013), and Kessler and Gupta (2015) for further discussion of specific practice options to manage water in topographic depressions.

Locations of depressions in agricultural fields may be suited for several types of conservation practices, including NRCS practice codes: 620 - Underground Outlet, 657 – Wetland Restoration

The Depression identification tool identifies surface depressions in the input DEM. This is performed by performing a “fill” process on the input DEM, then subtracting the input DEM from the filled DEM. Depression regions are then converted to polygons, and polygons are overlaid with the input DEM to extract the range of elevation values within each depression. This range of values represents the maximum depths of ponding that may occur in each depression. Polygons are also overlaid with gSSURGO to determine the mean percent of hydric soils within each depression.

Kessler, A.C., and S.C. Gupta. 2015. Drainage impacts on surficial water retention capacity of a prairie pothole watershed. Journal of the American Water Resources Association. 51(4): 1101-1113.

Smith, D.R., and S.J. Livingston. 2013. Managing farmed closed depressional areas using blind inlets to minimize phosphorus and nitrogen losses. Soil Use and Management. 29:94-102.