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Step 1: Assess Riparian Resource Function Using PFC §1d. Complete PFC assessment l 17 questions about attributes and processes l Reminder – PFC based on: Water (hydrology), Vegetation, and Soil & landform (erosion/deposition) l Checklist answers: Yes, No, or N/A (sometimes) l Not “Liner” l Notes for “No’s”, Many (all?) “Yes’s”, e g. species list
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Item #1: Floodplain inundation Floodplain l Level area near a stream channel l Constructed by the stream l In the present climate l Flooded during moderate & high flow events l Should not be confused with terraces (abandoned floodplains) (adapted from Leopold 1994) Abandoned floodplain or terrace Floodplain Channel Hill slope Valley flat
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Floodplain – Geologic feature being formed by the river in its present condition and climate
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Bankfull Concept Information Forest Service Stream Systems Technology Center (Stream Team) website for on-line training videos, can order CDs and DVDs: www.stream.fs.fed.us 1.Western U.S. 2.Northeastern U.S. (4 CDs) 3.Forested Streams Eastern U.S. http://www.stream.fs.fed.us/publications/bankfull_west.html
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Bankfull Indicators (Moody et al. 2003, Odem and Moody 1999) Build a case based on physical evidence Series of depositional features at consistent elevations with similar substrate and veg components Point bars at inside of meander bends, Point bars often not well developed with low sinuosity, Discontinuous alternating longitudinal bars parallel to the channel often most dependable indicator Broad valley floors are almost always above bankfull Field Observations
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Floods Terrace Bankfull
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One year flow
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Item 1: Floodplain inundated frequently 1) Floodplain inundated in “relatively frequent events” (1-3 years) l Purpose: To determine whether frequent flood flows are capable of spreading out on low-lying areas adjacent to the stream and thus provide for: energy dissipation sediment deposition periodic flooding of vegetation, and periodic infiltration of flood water to replenish base flows Bankfull Floodplain
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Item 1: Floodplain inundated frequently 1) Floodplain inundated in “relatively frequent events” (1-3 years) l Flat, depositional surface adjacent to channel Low gradient, meandering (“C” and “E” channels) Moderate gradient “B” channels l Indicators Channel incision Vertical banks on inside of bend & at straight reaches Upland vegetation on streambank Bankfull Floodplain
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Bankfull Terrace
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Item 2: Beaver dams are stable Purpose: Beaver dams are hydrologic modifiers. Stable dams can increase stability by attenuating flood flows, providing a source for base flows, storing sediment, raising water tables and expanding riparian areas. Unstable dams can reduce stability by causing channel incision, increasing bank erosion, lowering water tables and decreasing the extent of the riparian zone when they fail.
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l Indicators of beaver activity Fresh workings on dams Available building materials and food supply l Indicators of dams at risk Single dams No signs of maintenance and repair Confined valleys - no floodplain Large, flashy streams Item 2: Beaver dams are stable
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2: Beaver dams are stable §Examples of visual indicators l Dam construction material l Dams keyed into streambanks l Breaches YesNoNA
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Item 3: Dimension, Pattern and Profile 3) Sinuosity, gradient, and width/depth ratio, are in balance with the landscape setting (i.e., landform, geology, and bioclimatic region) Purpose: To determine if the pattern, dimension, and profile of the stream are within the expected range, given its landscape position, hydrologic regime, and natural sediment load. Sinuosity, width/depth ratio, and gradient perform key roles in determining whether a stream can transmit water and sediment while managing erosive forces and remaining stable
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Item 3: Dimension, Pattern and Profile 3) Sinuosity, gradient, and width/depth ratio, are in balance with the landscape setting (i.e., landform, geology, and bioclimatic region) l Question has three parts Sinuosity Width/Depth ratio Gradient l All three must be "yes" for answer to be "yes" l Must be appropriate for site
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Sinuosity = Stream Length ÷ Valley Length 1.9 = 370' ÷ 195' Valley Gradient = 1.5% Stream Gradient = 0.8%
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3) Sinuosity, gradient, and width/depth ratio, are in balance with the landscape setting (i.e., landform, geology, and bioclimatic region) §Examples of visual indicators l Aerial photos help with sinuosity
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3.) Sinuosity, gradient, and width/depth ratio, are in balance with the landscape setting (i.e., landform, geology, and bioclimatic region)
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4.) Riparian zone is expanding or has achieved potential extent. Purpose: To document that a riparian area is recovering or has recovered.
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§Examples of visual indicators l Riparian-wetland community types expanded to valley edge l Stream narrowed l Upland plants dying or dead l Depositions being captured 4) Riparian area is expanding or has achieved potential extent YesNoNA
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Item 5: Riparian impairment from the upstream or upland watershed is absent.
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5: Riparian impairment from the upstream or upland watershed is absent. Trapping Cr BC 1996 Belgo Cr BC 1996 YesNoNA YesNoNA
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Degradation related to upstream or upland factors Is there riparian degradation? No riparian degradation observed. Item 5 = “Yes” Yes, riparian degradation observed Degradation related to in situ activities Item 5 = “Yes” Item 5 = “No” Yes No Purpose: To determine if riparian degradation is caused by a management within the riparian area or by environmental conditions or management outside the riparian area.
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