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US Army Corps of Engineers

US Army Corps of Engineers. Detroit District. Knife River Reducing Sediment Delivery Through Forest Restoration. US Army Corps of Engineers. Detroit District. Drainage Area = 88 mi 2 Mostly forested Close to Duluth Only naturalized wild steelhead population in MN

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US Army Corps of Engineers

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  1. US Army Corps of Engineers Detroit District Knife River Reducing Sediment Delivery Through Forest Restoration

  2. US Army Corps of Engineers Detroit District • Drainage Area = 88 mi2 • Mostly forested • Close to Duluth • Only naturalized wild steelhead population in MN • Only MN trib to Great Lakes w/o fish migration barrier

  3. Knife River Background US Army Corps of Engineers Detroit District Federal Harbor Knife River is a significant source of sediment to the lake and harbor and has use impairments due to sediment. As such, a TMDL has been established.

  4. US Army Corps of Engineers Detroit District Knife River Source of Sediment Mass Wasting

  5. US Army Corps of Engineers Detroit District Knife River The Problem • The Knife River watershed was historically composed of old-growth red and white pines with some hardwoods. Modern logging activities have replaced those species with a mono-culture of aspen. Local scientists believe that this shift is species has altered the hydrologic response of the watershed resulting in increased flashiness and increased erosion. Local stakeholders are interested in initiating a forest restoration program but would like the following questions answered first: • How large of a reduction in sediment delivery is expected if the forest is restored to pre-European settlement species? • Are some sub-watersheds more sensitive to restoration than others? • What role does the beaver play in storing sediment and reducing flashiness?

  6. US Army Corps of Engineers Detroit District Knife River Summary • Watershed response to forest restoration modeled with HSPF • Impact of beaver dams on sediment supplies modeled with RAS • Hydrologic sensitivity index developed • Historic flows statistically analyzed

  7. US Army Corps of Engineers Detroit District First Date with Knife River Temperature and Precipitation

  8. US Army Corps of Engineers Detroit District Knife River Soils and Topography Clay-Rich Till Average Slope = 0.8 %

  9. US Army Corps of Engineers Detroit District Knife River Land Cover and Forest Canopy

  10. US Army Corps of Engineers Detroit District Knife River Watershed Model - HSPF

  11. US Army Corps of Engineers Detroit District Knife River Watershed Model - HSPF • Calibrated to Flow at d/s gage

  12. US Army Corps of Engineers Detroit District Knife River Watershed Model – Extent of Forest Restoration

  13. US Army Corps of Engineers Detroit District Knife River Watershed Model – Extent of Forest Restoration

  14. US Army Corps of Engineers Detroit District Knife River Watershed Model – Tree Age

  15. US Army Corps of Engineers Detroit District Knife River Watershed Model – Tree Age

  16. US Army Corps of Engineers Detroit District Knife River Beaver Influence on Sediment • Castor canadensis is the largest rodent in North America, growing to 60 lbs over an average life span of 24 years. • Beaver dams can significantly affect stream flashiness • Beaver dams can store a large quantity of sediment • A large pulse of sediment can be mobilized upon breaching

  17. US Army Corps of Engineers Detroit District Knife River Beaver Confusion Castor canadensis Intern canadensis

  18. US Army Corps of Engineers Detroit District Knife River Beaver Influence on Sediment

  19. US Army Corps of Engineers Detroit District Knife River Summary of flow at USGS Gage

  20. US Army Corps of Engineers Detroit District Knife River Flashiness Index No Trend

  21. Knife River Flashiness Index US Army Corps of Engineers Detroit District

  22. Knife River Flashiness Index US Army Corps of Engineers Detroit District

  23. US Army Corps of Engineers Detroit District Hydrologic Sensitivity Index Ranks hydrologic sensitivity of sub-basins based on slope, distance to outlet and percent disturbed land

  24. US Army Corps of Engineers Detroit District Knife River Conclusions • Forest restoration to Pre-European species will have a minimal effect on altering stream flows except in a few sub-watersheds • Beaver dams will store water and reduce the flashiness of the stream at low flows, but have no effect once the 2-yr flow is exceeded • Beaver dams only temporarily impound sediment. Larger waves of sediment are likely released when a dam or multiple dams fail

  25. US Army Corps of Engineers Detroit District Questions? Contact: Dr. Jim Selegean, P.E., P.H. U.S. Army Corps of Engineers, Detroit District Great Lakes Hydraulics and Hydrology Office 477 Michigan Ave Detroit, MI 48226 313.226.6791 james.p.selegean@usace.army.mil

  26. US Army Corps of Engineers Detroit District

  27. US Army Corps of Engineers Detroit District Figure 39: Impacts of different beaver dam densities with unsteady flow modeling. a) far downstream cross-section b) downstream cross-setion c) cross-section immedietly downstream of dams d) within beaver dam section e) upstream of beaver dams - The black dashed line indicates time of first dam breach

  28. US Army Corps of Engineers Detroit District

  29. US Army Corps of Engineers Detroit District

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