Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 22, 89-110, 2018
https://doi.org/10.5194/hess-22-89-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
08 Jan 2018
Comparison of performance of tile drainage routines in SWAT 2009 and 2012 in an extensively tile-drained watershed in the Midwest
Tian Guo1,2, Margaret Gitau1, Venkatesh Merwade1,3, Jeffrey Arnold4, Raghavan Srinivasan5, Michael Hirschi6, and Bernard Engel1 1Department of Agricultural & Biological Engineering, Purdue University, West Lafayette, IN 47907, USA
2National Center for Water Quality Research, Heidelberg University, 310 E Market St, Tiffin, OH 44883, USA
3Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47906, USA
4USDA-ARS, Grassland Soil and Water Research Laboratory, Temple, TX 76502, USA
5Spatial Sciences Laboratory in the Department of Ecosystem Science and Management, Texas A&M University, College Station, TX 77843, USA
6Department of Agricultural & Biological Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
Abstract. Subsurface tile drainage systems are widely used in agricultural watersheds in the Midwestern US and enable the Midwest area to become highly productive agricultural lands, but can also create environmental problems, for example nitrate-N contamination associated with drainage waters. The Soil and Water Assessment Tool (SWAT) has been used to model watersheds with tile drainage. SWAT2012 revisions 615 and 645 provide new tile drainage routines. However, few studies have used these revisions to study tile drainage impacts at both field and watershed scales. Moreover, SWAT2012 revision 645 improved the soil moisture based curve number calculation method, which has not been fully tested. This study used long-term (1991–2003) field site and river station data from the Little Vermilion River (LVR) watershed to evaluate performance of tile drainage routines in SWAT2009 revision 528 (the old routine) and SWAT2012 revisions 615 and 645 (the new routine). Both the old and new routines provided reasonable but unsatisfactory (NSE  <  0.5) uncalibrated flow and nitrate loss results for a mildly sloped watershed with low runoff. The calibrated monthly tile flow, surface flow, nitrate-N in tile and surface flow, sediment and annual corn and soybean yield results from SWAT with the old and new tile drainage routines were compared with observed values. Generally, the new routine provided acceptable simulated tile flow (NSE  =  0.48–0.65) and nitrate in tile flow (NSE  =  0.48–0.68) for field sites with random pattern tile and constant tile spacing, while the old routine simulated tile flow and nitrate in tile flow results for the field site with constant tile spacing were unacceptable (NSE  =  0.00–0.32 and −0.29–0.06, respectively). The new modified curve number calculation method in revision 645 (NSE  =  0.50–0.81) better simulated surface runoff than revision 615 (NSE  =  −0.11–0.49). The calibration provided reasonable parameter sets for the old and new routines in the LVR watershed, and the validation results showed that the new routine has the potential to accurately simulate hydrologic processes in mildly sloped watersheds.

Citation: Guo, T., Gitau, M., Merwade, V., Arnold, J., Srinivasan, R., Hirschi, M., and Engel, B.: Comparison of performance of tile drainage routines in SWAT 2009 and 2012 in an extensively tile-drained watershed in the Midwest, Hydrol. Earth Syst. Sci., 22, 89-110, https://doi.org/10.5194/hess-22-89-2018, 2018.
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Short summary
The new tile drainage routine in the SWAT model provided more realistic and accurate simulation of tile drainage, and the new curve number retention parameter adjustment factor improved surface runoff simulation, and is suitable for surface runoff simulation in mildly sloped watersheds. This study can provide guidance for selection of tile drainage routines for tile drainage simulation, and can allow accurate simulation of hydrological systems at both field and watershed scales.
The new tile drainage routine in the SWAT model provided more realistic and accurate simulation...
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