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Blanchard Watershed Modeling

Blanchard Watershed Modeling. Laura Weintraub, Amanda Flynn, Joe DePinto Great Lakes Tributary Modeling Program 516(e) Meeting May 18, 2011. Western Basin Lake Erie. Concerns Sedimentation Increasing SRP loads Algae blooms Maumee Basin Largest tributary sediment source to Lake Erie

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Blanchard Watershed Modeling

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  1. Blanchard Watershed Modeling Laura Weintraub, Amanda Flynn, Joe DePinto Great Lakes Tributary Modeling Program 516(e) Meeting May 18, 2011

  2. Western Basin Lake Erie • Concerns • Sedimentation • Increasing SRP loads • Algae blooms • Maumee Basin • Largest tributary sediment source to Lake Erie • Highly agricultural watershed (~80%) • Focus of WLEB Partnership • Maumee Bay / Toledo Harbor dredging • Annual volume: ~640,000 yd3 (2004-08) • Annual cost: ~$5 million

  3. Sources to Western Basin of Lake Erie (2005)

  4. Blanchard River Watershed: Project Overview • Fine-scale Watershed Models of the Maumee Basin Objectives • Continue effort to apply fine-scale models to Maumee watersheds (build upon Upper Auglaize) • Quantify sediment and nutrient loading • Evaluate land management alternatives to estimate potential benefit from reduced loading • Support broader sediment and nutrient modeling efforts of the lower Maumee River and Maumee Bay Funding Under 516(e) Timeline: Jul 2009 to Oct 2010

  5. Integrated Project Team USACE- ERDC Billy Johnson Contracting, Technical Review USACE- Buffalo District Byron Rupp Funding, Technical Review, Project Oversight LimnoTech Joe DePinto, Greg Peterson Laura Weintraub Amanda Flynn, Pranesh Selvendiran Technical Lead, Project Management, Reporting USDA-NRCS Jim Stafford, Steve Davis Soils, Crop Management Heidelberg Univ. Pete Richards Historical WQ Data Project Team USDA-ARS Ron Bingner, Fred Theurer AnnAGNPS Model Support USGS Greg Koltun Hydraulic Geometry, Climate Univ. of Toledo Kevin Czajkowski, David Dean GIS Data (Topography, Land Cover, Soils) Additional Technical Support Nutrients(OSU – Libby Dayton) Point Sources (OEPA)

  6. Blanchard River Watershed • Population : 91,266 • Area : 771 miles2 • 6 major subbasins within 6 counties • Low slope (typically < 2%) • Poorly drained soils (42% hydric) • Cropland > 80% (Beans, Corn, Wheat) • Drains into the Auglaize River

  7. AnnAGNPS Background Developed by USDA-ARS • Continuous simulation of surface runoff and pollutant loading • Incorporates revised universal soil loss equation (RUSLE) • Provides most utility at monthly or annual scales Models flow, suspended solids, and nutrients • Simulates direct surface runoff and tile drain flow based on SCS curve number • Distinguishes between sheet and rill, ephemeral gully erosion

  8. AnnAGNPS Sediment Erosion • Sheet and Rill Erosion • Overland flow or small concentrated flow paths • Calculated based on RUSLE • AnnAGNPS algorithmsthoroughly tested • Ephemeral Gully Erosion • Erosion in deep, narrow channels • Calculated based on TI-EGEM • Limited testing of AnnAGNPS algorithms Ephemeral Gully Erosion Sheet and Rill Erosion

  9. AnnAGNPS Data Requirements

  10. Spatial Input Data Model Cell Delineation with Dominant Soils Potential Ephemeral Gully Locations 3,830 cells Average cell size = 52 ha • Approximately 1500 PEG sites • Function of: • CTIndex (1000) • Watershed topography

  11. 2005-2008 Crop and Tillage Rotation • Data from remote sensing - compared with NRCS transect data • Developed a detailed four (4) year crop rotation and tillage operation sequence for each cropland cell • Removed unrealistic combinations (Example: WNCTCMSN)

  12. Model Calibration/Confirmation Datasets and Time Periods • Hydrology • USGS (04189000) at Findlay – 1923 to Current (daily) • USGS (01489950) at Cuba – 2005 to 2007 (daily) • Water Quality (solids, nitrogen, phosphorus) • Heidelberg at Findlay – 2007 to Current (daily) • OEPA seven “sentinel” stations – 2005 to 2006 (~ 2x per month) • OEPA ~100 stations – 1991 to 2008 (variable and infrequent) • Calibration  2002 – 2009 • Confirmation  1995 – 2001

  13. Hydrology Calibration • Calibration resulted in a “good” to “very good” prediction of runoff • Runoff slightly over-predicted at Cuba and slightly under-predicted at Findlay • Annual performance better than monthly or daily

  14. Hydrology Calibration (continued) • Runoff under-predicted late winter/early spring and over-predicted summer/early fall time periods

  15. Water Quality Calibration (Sediment) • Annual performance “very good” • Monthly and daily performance less robust ranging from “fair to good” • Ephemeral gully erosion was 85% of the total landscape erosion

  16. Water Quality Calibration (Total Phosphorus and Total Nitrogen) • “Poor” to “fair” performance • Sensitive to initial soil concentrations • Limitations in model capabilities for nutrient cycling • Fertilizer application timing in model may not reflect “on the ground” practices Total P Total N

  17. AnnAGNPS Model Application • Goal: Test the impact of land management alternatives on watershed loadings • Process: • Coordinate with stakeholders to develop a set of reasonable BMPs/land management alternativesNRCS, Blanchard River Watershed Partnership, Environmental Defense Fund, Putnam Soil and Water Conservation District, Ohio DNR,Northwest Ohio Flood Mitigation Partnership • Translate BMPs into model, direct or indirect representations • Run scenarios and interpret results

  18. Selected Management Alternatives • Tile Drain Management • Conservation Tillage • Cover Crops • Cropland Conversion to Grassland • random cropland (~10%) to grassland • targeted cropland (~10%) to grassland • Improved Nutrient Management • All Natural Watershed • Combined Management • conservation tillage + cropland to grassland + nutrient management

  19. Example BMP Scenario Convert dominant highly erodible cells to improved rotation and tillage Rotating Corn and Beans with Conservation Tillage (CMBNCMBN) Continuous Corn with Traditional Till (CTCTCTCT or CTCTBNCT) Moldboard plow Mulch till • Converted 7,683 acres • 2.5 % of total crop area • 56 watershed cells continuous corn with traditional till corn/bean rotation with conservation till

  20. Sediment Alternative Scenario Results Base versus Combined Management • Random cropland conversion = -2% • Targeted cropland conversion = -54% • Combined management = -60%

  21. Sediment Maps Base Case Combined Management Scenario Example: Sediment load reduction in Lye Creek Watershed due to improved land management practices

  22. Phosphorus Alternative Scenario Results Base versus Combined Management • Cover crops across all conventional tilled land = -25% • Reduce fertilizer by 60% = -21% • Combined management = -24%

  23. Nitrogen Alternative Scenario Results Base versus Combined Management • Conservation tillage = -24% • Cover crops across all conventional tilled land = -39% • Combined management = -75%

  24. Project Summary • Fine-scale model adequately simulates runoff and suspended sediment on annual basis • Less confidence in simulation of TN and TP loading • Potential land management alternatives explored to estimate possible benefits • Targeting placement of BMPs to highly erodible areas likely to result in higher reductions of loads • Final report available from GLC (October 19, 2010)

  25. Recommendations for Future Work • Examine additional management scenarios: • Seasonal variations of tile drains and nutrient application • Conversion to conservation tillage, cover crops, or grassland • Investigate and potentially refine nutrient algorithms • Investigate / ground-truth ephemeral gully erosion algorithms • Use model to support watershed action plan development • Apply fine-scale models to other Maumee Basin watersheds (e.g., Tiffin) • Coordinate with modeling to characterize sediment and nutrient transport in the lower Maumee River / Toledo Harbor

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