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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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slide1
US Army Corps

of Engineers

Detroit District

Knife River

Reducing Sediment Delivery Through Forest Restoration

slide2
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
slide3
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.

slide4
US Army Corps

of Engineers

Detroit District

Knife River

Source of Sediment

Mass Wasting

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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?
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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
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US Army Corps

of Engineers

Detroit District

First Date with Knife River

Temperature and Precipitation

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US Army Corps

of Engineers

Detroit District

Knife River

Soils and Topography

Clay-Rich Till

Average Slope = 0.8 %

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US Army Corps

of Engineers

Detroit District

Knife River

Land Cover and Forest Canopy

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US Army Corps

of Engineers

Detroit District

Knife River

Watershed Model - HSPF

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US Army Corps

of Engineers

Detroit District

Knife River

Watershed Model - HSPF

  • Calibrated to Flow at d/s gage
slide12
US Army Corps

of Engineers

Detroit District

Knife River

Watershed Model – Extent of Forest Restoration

slide13
US Army Corps

of Engineers

Detroit District

Knife River

Watershed Model – Extent of Forest Restoration

slide14
US Army Corps

of Engineers

Detroit District

Knife River

Watershed Model – Tree Age

slide15
US Army Corps

of Engineers

Detroit District

Knife River

Watershed Model – Tree Age

slide16
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
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US Army Corps

of Engineers

Detroit District

Knife River

Beaver Confusion

Castor canadensis

Intern canadensis

slide18
US Army Corps

of Engineers

Detroit District

Knife River

Beaver Influence on Sediment

slide19
US Army Corps

of Engineers

Detroit District

Knife River

Summary of flow at USGS Gage

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US Army Corps

of Engineers

Detroit District

Knife River

Flashiness Index

No Trend

slide21
Knife River

Flashiness Index

US Army Corps

of Engineers

Detroit District

slide22
Knife River

Flashiness Index

US Army Corps

of Engineers

Detroit District

slide23
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

slide24
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
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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

[email protected]

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US Army Corps

of Engineers

Detroit District

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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

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US Army Corps

of Engineers

Detroit District

slide29
US Army Corps

of Engineers

Detroit District

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