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Predicting natural channel types in the Columbia River basin. Hiroo Imaki 1 , Tim Beechie 1 , John Buffington 2 1. NOAA, Northwest Fisheries Science Center, 2. USFS, Rocky Mountain Research Station 2010.10.28. Questions. Where are we now? How much habitat we used to have?
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Predicting natural channel types in the Columbia River basin HirooImaki1, Tim Beechie1, John Buffington2 1. NOAA, Northwest Fisheries Science Center, 2. USFS, Rocky Mountain Research Station 2010.10.28
Questions • Where are we now? • How much habitat we used to have? • Where are we going? • Restore or not? • Where? • How much we can gain? • How much do we have to pay?
Columbia River Basin Historical Ecology Project Channel Type Riparian Vegetation Salmon Distribution
Project Objectives • Establish a guideline to restore stream processes for endangered salmon and biodiversity • Our methods and products can be used as… • Natural channel type template for restoration • Restoration prioritization tool
Our common perspective Columbia River Basin Area668,000km2 Total stream length 444,121 km
Why Channel Types? • Process-based channel classification • Natural or potential channel types • Restoration potential or target • Large geographic scale • Map presentation of physical channel type • Prioritization tool • Simplicity • Easy to explain and communicate!
Floodplain Channel Types Straight Meandering Island-braided Braided Beechie et al. (2006)
Mountain Channel Types Cascade Plane-bed Pool-riffle Step-pool Montgomery and Buffington (1997)
Channel Type System Reach Yes No BFW< 8 m * Confined Prediction Model * * Hall et al. (2007) * Support Vector Machine Slope < 0.015 Confined Braided Pool-riffle Slope < 0.03 Plane-bed Island-braided Slope < 0.065 Step-pool Meandering Cascade Straight Mountain Channels Floodplain Channels Beechie and Imaki (in review) Montgomery and Buffington (1997)
Methods Flow direction GIS data preparation (DEM, stream, etc.) Field measurements Profile C B A Reach • Slope • Bankfull width • Floodplain width • Relative shear stress (RSS) • Fine sediment supply • Fine sediment • Alpine sediment • Root strength / Wood supply - + RSS Calculate geomorphic characteristics Relative shear stress Establish channel type reference reaches Build a model and predict channel types (Support Vector Machine)
Accumulated Precipitation (BFW) Slope 8e+06 0.06 0.04 Slope(m/m) Accummulated precipitation (mm) 4e+06 0.02 0e+00 0.00 Island- braided Island- braided Braided Meandering Straight Braided Meandering Straight Confinement Relative Shear Stress 200 150 100 0 100 Relative shear stress (N/m2) Channel confinement (fpw/bfw) -100 50 -200 0 Island- braided Island- braided Braided Meandering Straight Braided Meandering Straight Fine Sediment Alpine Sediment 100 25 80 20 60 15 Alpine sediment supply area (%) Fine sediment supply area (%) 40 10 20 5 0 0 Island- braided Island- braided Braided Meandering Straight Braided Meandering Straight
N Snake River Grand Ronde Columbia River 50 km 0
Prediction accuracy and error Channel type ~ Slope + acc_precip + r_stress + fine_sediment + alpine_sediment Overall accuracy = 76% Kappa = 0.69