1. Agricultural Subsurface Drainage USGS Staff: Nancy Baker, Wes Stone GIS Contact: Michael Wieczorek

2. 1.It is impossible to identify the exact location of subsurface drains in the conterminous U.S. (Sugg, Jayne, Naz, Brown) 2.The primary goal is to provide an estimate of the probable percent of agricultural land that may have subsurface drains to facilitate cropping at a National scale (CONUS). 3.This is an exploratory exercise at this point and will build of the work of others as well as incorporate input from various Federal Agencies and Universities. 4.No previous work has been done on the National scale (CONUS) or with the most recent available data at the National scale (SSURGO, CDL, NLCD).

3. ResearchersLand Use DataSoils DataComments Jaynes and James, 2004NLCD, 1992STATSGO Drainage classes, Hydrologic Groups, Land Capability Class Slope was also included in the analysis 23 States in the MidWest and East Sugg, 2007NLCD, 1992STATSGO Drainage classes, Hydrologic Groups Final estimates used drainage class only MidWestern Corn belt only Naz et al, 2009NLCD, 1992STATSGO Drainage classes Slope was also included in the analysis Hoagland Watershed, IN only Brown, 2009NLCD, 2001SSURGO Drainage classes, Hydrologic Groups, Land Capability Class Slope was also included in the analysis Central Minnesota only

4. 1.The exact locations of tile drains are incomplete or unknown. 2.If row crops are cultivated on poorly drained soils, then artificial drainage likely exists. 3.1992 remains the most recent complete data set at the county level for CONUS for Tile Drains. 4.No method exists for distinguishing between surface and subsurface drainage. 5.No study has been done at the National level (CONUS) or with new data sets (SSURGO, CDL, NLCD). 6.Further exploration may lead to different approaches for different areas as well as incorporating other data sets.

5. 1.1992 NRI 2.Hydrologic Group 3.Drainage Class 4.Water Table Depth April June Minimum 5.Available Water Storage 0 - 25 cm 6.Soil Restrictive layer 7.NLCD 2011 8.Crop Land Data Layer 2013 Approaches/Data Sources

6. Comparison of Suggs 1992 NRI vs USGS 1992 NRI

7. Hydrologic Groups and Water Table Depth during April – June ( 100 cm or less) Source Data: SSURGO

8. Drainage Classes and Soil Restrictive layer ( 25 cm or less) Source Data: SSURGO

9. Comparison of Hydrologic Groups and USGS 1992 NRI

10. Comparison of Water table Depth and USGS 1992 NRI

11. Comparison of Drainage Classes and USGS 1992 NRI

12. Comparison of Soil Restrictive Layer (25cm) and USGS 1992 NRI

14. COUNTAGHydGrpSRL25AGDrainageClassWTDEPTILESPCT 4314713011153.29883 1058713010113.07796 34531300114.265438 6771300010.836288 6171311010.762171 45891311115.668721 851310010.104999 5161310110.637407 50681200116.260423 25501200013.149976 3601201110.444702 4031201010.49782 611210110.075352 2331210010.287821 191211010.02347 131211110.016059 38821100114.795375 29381100013.629266 4701101010.580584 9661101111.193285 271110110.033353 101111010.012353 111111110.013588 181110010.022235 1341000110.165528 891000010.10994 61001110.007412 21010010.002471 171010110.021 21011110.002471 11001010.001235 21011010.002471 80953 100

15. Leary-Weber Ditch, IN Blue = Ag land and NRI 1992 Tiles 100% Brown = All other areas

16. COUNTTLES100PCTAGHGDOMPCT 80105985000 20524670001 46669727010 47800312011 220763611029.00647 457627311160.12836 3988391005.240407 4280921015.624767 7610840 TILES100PCT 1 = 100% NRI92, 0 = not AG 1 = cropland and, 0 = not HGDOM 1 = COMBO, 0 = not

17. COUNTAG andTilewtdep < 100 cmhydgrppct 499809811365.67 238324411231.31 1500341111.97 291941020.38 254211100.33 185821010.24 62671030.08 7610840 AG andTile 1 = cropland and 100% tile (92NRI), 0 = not wtdep < 100 cm 1 = SSURGO water table during Apr- May-June < 100 cm hydgrp 1 = AorB, 2 = CorD, 3 = any COMBO

21. Questions?