Strategies Addressing Hydromodification in Channels Through Unstable Terrains

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Strategies Addressing Hydromodification in
Channels Through Unstable Terrains

• John Gartner
• Barry Hecht
• Shawn Chartrand
• Edward Ballman, P.E.
• BALANCE HYDROLOGICS, INC.

NOTE First half of presentation is in Gartner
GSA talk hydromodification 5-1-05 part 1.pdf
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Stream walks Sediment Point Sources

• Bank Failure
• Knickpoint
• Earthflow

Incising tributaries
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Custom modeling with HEC-HMS for middle watershed
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Modeling middle reach effects
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Solutions

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1. Headwater Detention (slight) 2. Reduce Peaks
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3. Detention (hyper)
Measured bankful
Measured Bankful
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4. Avoid Most Vulnerable Channels
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5. Improved Grazing Management
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6. Strategic Channel Stabilization
Photo courtesy of LSA Associates
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Summary

• Hydromodification is a vital issue in the
  urbanizing West, especially in areas with
  geologic or geomorphic disturbance.
• Solutions are often best approached from geologic
  perspective
• Recognizing the one-time nature of channel
  adjustment
• Based on intensive field work in disturbed
  landscapes.
• Value of baseline data flow, sediment,
  channels.
• Solutions should spring from watershed
  perspective and work with site conditions.

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Interdisciplinary effort and review
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Thompson Creek, San Jose