Although some data on the national scale exists in tabular form, such as Ag Census and NRI, many researchers struggle with the limitations of this content. Perceived limitations include methods of data collection, precision, and initial definitions of variables used in analysis (for example, what constitutes poorly drained soils) and the identification of the differences between types of drainage (surface versus tiles). Because of these limitations, defining tile drains using spatial analysis is even more difficult than probabilistic methods (but that do not give as precise location).
NEW: Low-altitude multispectral and thermal-infrared imagery from agricultural fields, Black Creek basin, Allen County, IN - spring 2017, Tanja Williamson
County-level "Land drained by tile" (and other land use practices) from the 2012 Census of Agriculture
Nakagaki, N., and Wieczorek, M.E., 2016, Estimates of Subsurface Tile Drainage Extent for 12 Midwest States, 2012: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F7W37TDP
Nakagaki, N., Wieczorek, M.E., and Qi, S.L., 2016, Estimates of Subsurface Tile Drainage Extent for the Conterminous United States, early 1990s: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F7RB72QS\
- Andrew LaMotte and Dave Wolock looked into the historical Ag Census data where subsurface drainage has been reported. Only 1969 and 1974 is available and state level for 2012. County level reporting stopped with the 1974 Census. Years prior to 1969 were reported, but no tables have been produced digitally.
- Mike Wieczorek (USGS) presented to NAWQA leadership on spatial coverages of tile drains. See attachment, Agricultural Subsurface Drainage.pptx.
- Tanja Williamson (USGS) has been looking into airborne/satellite imaging as a way to map tile drains, https://doi.org/10.5066/F7Q81C9V.
- Ray Finocchiaro, U.S. Geological Survey, Northern Prairie Wildlife Research Center, Agricultural Subsurface Drainage Tile Locations by Permits in South Dakota
- Michael Schwartz, Opportunity Landscapes - Drainage Water Management