Tiffin River Great Lakes Tributary Modeling Program Development and Application of the Tiffin River Watershed Soil and Water Assessment Tool (TRSWAT)
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Tiffin River Great Lakes Tributary Modeling Program Development and Application of the Tiffin River Watershed Soil and Water Assessment Tool (TRSWAT) Prepared for: U.S. Army Corps of Engineers, Buffalo District Final October 17, 2013 This page is blank to facilitate double-sided printing Page | ii Tiffin River Great Lakes Tributary Modeling Program Development and Application of the Tiffin River Watershed Soil and Water Assessment Tool (TRSWAT) Prepared for: U.S. Army Corps of Engineers, Buffalo District Under Contract to: Ecology and Environment, Inc. October 17, 2013 This page is blank to facilitate double-sided printing Page | iv Tiffin River Great Lakes Tributary Modeling Program October 2013 Development and Application of the Tiffin River Watershed Soil Water Assessment Tool (TRSWAT) Final TABLE OF CONTENTS Executive Summary ......................................................1 1 Introduction .............................................................. 4 1.1 Background ....................................................................... 4 1.2 Project Objectives ............................................................. 5 1.3 Partner Agencies ............................................................... 5 1.4 Project Scope ..................................................................... 6 1.4.1 Quality Control Plan ................................................ 6 1.4.2 Project Scoping and Model Selection ...................... 7 1.4.3 Model Refinement ................................................... 7 1.4.4 Model Development ................................................ 7 1.4.5 Model Calibration/ Confirmation and Alternative Scenario Selection ..................................................... 8 1.4.6 Alternatives Modeling ............................................. 8 1.5 Scope of Report ................................................................. 8 2 Characteristics of the Tiffin River Watershed ............ 9 2.1 Physical Characteristics .................................................... 9 2.1 Topography ...................................................................... 11 2.2 Soils .................................................................................. 11 2.3 Land Use .......................................................................... 12 2.4 Climate ............................................................................. 12 2.5 Impairments and Pollution Prevention ........................... 13 3 Model Development ................................................. 14 3.1 Model Selection ................................................................ 14 3.2 Overview of the Soil and Water Assessment Tool (SWAT) ......................................................................................... 15 3.3 SWAT Model Refinements .............................................. 16 3.3.1 Spatial Explicitness ................................................ 16 3.3.2 Incorporation of Ephemeral Gully Erosion ........... 17 3.3.3 Instream Kinetics ................................................... 18 3.4 Model Inputs .................................................................... 18 3.4.1 Climate .................................................................... 19 3.4.2 Reservoirs ............................................................... 19 3.4.3 Agriculture Input Data ........................................... 19 4 Model Calibration and Confirmation ....................... 27 4.1 Calibration and Confirmation Approach ........................ 27 4.1.1 Calibration and Confirmation Periods .................. 27 4.1.2 Model Calibration Approach ................................. 29 4.1.3 Model Confirmation Approach ............................. 29 4.1.4 Visual Evaluation and Statistical Metrics ............. 29 4.1.5 Model Performance Targets ................................... 31 4.1.6 Calibration and Confirmation Data ...................... 33 Page | v Tiffin River Great Lakes Tributary Modeling Program October 2013 Development and Application of the Tiffin River Watershed Soil Water Assessment Tool (TRSWAT) Final 4.2 Calibration and Confirmation Results ............................ 34 4.2.1 Hydrology .............................................................. 34 4.2.2 Sediment ................................................................ 42 4.2.3 Phosphorus ............................................................ 47 4.2.4 Nitrogen ................................................................. 58 4.3 Analysis of Sediment and Nutrient Loading (Baseline) . 68 4.3.1 Sediment and Nutrient Sources ............................ 68 4.3.2 Sediment and Nutrient Pathways .......................... 71 5 Model Application ....................................................75 5.1 Management Scenario Descriptions ................................75 5.1.1 Grassed Waterways (A,B) .......................................75 5.1.2 Filter Strips (C) ...................................................... 76 5.1.3 Cover Crops (D) ..................................................... 76 5.1.4 Conservation Tillage (E) ......................................... 77 5.1.5 Improved Nutrient Management (F) .................... 78 5.1.6 Combined Management Scenario (G) ................... 78 5.2 Management Scenario Results ....................................... 78 5.2.1 Sediment ................................................................ 79 5.2.2 Phosphorus ............................................................ 85 5.2.3 Nitrogen ................................................................. 90 6 Summary and Recommendations ............................ 95 6.1 Summary ......................................................................... 95 6.2 Model Limitations and Caveats ...................................... 97 6.3 Recommendations for Future Work ............................... 98 7 References .............................................................. 99 Appendix A Model Calibration Parameterization ...... 101 Appendix B Model Calibration and Confirmation Statistics and Plots ............................................. 104 Appendix C Management Application Maps ............. 120 Appendix D Model Input Data Quality Evaluation ..... 128 Appendix E Tiffin River Watershed, Section 516(e) WRDA 1996, Great Lakes Tributary Modeling, Final Scoping Report ................................................... 130 Appendix F SWAT Model Refinement for the Incorporation of Ephemeral Gully Erosion ......... 148 Appendix G Development of the Tiffin River Watershed SWAT (TRSWAT) Model ...................................... 177 Page | vi Tiffin River Great Lakes Tributary Modeling Program October 2013 Development and Application of the Tiffin River Watershed Soil Water Assessment Tool (TRSWAT) Final LIST OF FIGURES Figure 1-1. Maumee River Basin subwatersheds .......................... 4 Figure 1-2. Project team for SWAT modeling in the Tiffin River watershed, Michigan and Ohio. ............................................ 6 Figure 2-1. Base map of the Tiffin River watershed, Michigan and Ohio. .................................................................................... 10 Figure 2-2. Tiffin River watershed elevation map (figure taken from NRCS 2008, USACE 2009) ........................................ 11 Figure 2-3. Tiffin River watershed annual rainfall characteristics (figure taken from NRCS 2008, USACE 2009). ................. 12 Figure 4-1. Annual rainfall for the Tiffin River watershed over the 2001-2011 time period. ....................................................... 28 Figure 4-2. TRSWAT annual average water balance (2001-2011) ............................................................................................. 36 Figure 4-3. Total annual and observed and simulated streamflow volume at Tiffin River at Stryker for the calibration period (2006-2011). ........................................................................ 39 Figure 4-4. Total annual and observed and simulated streamflow volume at Tiffin River at Stryker for the confirmation period (2001-2005). ....................................................................... 39 Figure 4-5. Total monthly simulated and observed streamflow volume at Tiffin River at Stryker for the calibration period (2006-2011). ........................................................................ 40 Figure 4-6. Total monthly simulated and observed streamflow volume at Tiffin River at Stryker for the confirmation period (2001-2005). ....................................................................... 40 Figure 4-7. Daily simulated and observed streamflow at Tiffin River at Stryker for the calibration period (2006-2011). .... 41 Figure 4-8. Daily simulated and observed streamflow at Tiffin River at Stryker for the confirmation period (2001-2005). 41 Figure 4-9. Total annual simulated sediment load at Tiffin River at Stryker compared with LOADEST estimated “observed” loads for the calibration (2009-2011) and confirmation time period (2007-2008). Error bars represent the 95th confidence interval. ............................................................. 44 Figure 4-10. Total monthly simulated sediment load at Tiffin River at Stryker compared with LOADEST estimated “observed” loads for the calibration time period (2009- 2011). Error bars represent the 95th confidence interval. ... 45 Figure 4-11. Total monthly simulated sediment load at Tiffin River at Stryker compared with LOADEST estimated