Routing, Synthesis and Watershed Analysis

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Routing, Synthesis and Watershed Analysis

• FE423 - February 10, 2000

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LABS

• Lab notes
• Due at 5pm Thursday
• Late penalty 10 per day

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OUTLINE

• Surface vs. Hydrologic Functions
• Synthesis
• Rain-on-Snow
• Road Routing

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REVIEWSurface vs. Hydrologic Functions

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SYNTHESIS

• Input Hazard
• Delivery Potential
• Cumulative Inputs
• Reach Sensitivity
• Fish Vulnerability

A hazard only becomes an Impact when it is
delivered to a sensitive fish bearing reach.
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SYNTHESIS

• Many things can prevent delivery to vulnerable
  reaches.
• Stopping
• Filtering
• Dispersion/Diffusion

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SYNTHESIS
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SYNTHESIS
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Snow Hydrology

Forested
Logged
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Snowfall

Canopy interception
Thick snowpack
Thin snowpack
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After/During Snowfall

Little melt
Canopy melt
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Warm Rainstorm

• Insulation
• wind slower
• air colder
• air drier

• Opening
• wind fast
• air warmer
• air humid

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After/During Rain Storm

Little melted Much left
Most melted Little left
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Harvest Impacts Snowmelt

• Canopy intercepts and melts snowfall before rain
  storm
• Canopy insulates snowpack from wind, warmth, and
  humidity
• So stands have less snowpack before and more
  after
• Resulting in less snowmelt to add to the rainfall

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Delivery to Streams

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Road Delivery

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Road Delivery

Road cuts intercept subsurface storm flow Ditches
route water to streams much quicker than soil
does Roads increase the area near the stream
network and can thus increase peakflow