Predicting natural channel types in the Columbia River basin
description
Transcript of Predicting natural channel types in the Columbia River basin
Predicting natural channel types in the Columbia River basin
Hiroo Imaki1, 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
SalmonDistribution
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
Columbia River BasinArea 668,000km2
Total stream length 444,121 km
Our common perspective
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 BraidedIsland-braided
Beechie et al. (2006)
Mountain Channel Types
Montgomery and Buffington (1997)
Cascade
Step-pool
Plane-bed
Pool-riffle
Channel Type System
Pool-riffle
Step-pool
Plane-bed
Cascade
Slope < 0.015
Slope < 0.03
Slope < 0.065
BFW< 8 m *
Meandering
Island-braided
Braided
Straight
Reach
Prediction Model *
Mountain Channels Floodplain Channels
Yes
No
Montgomery and Buffington (1997)
* Hall et al. (2007)
Confined
Confined
Beechie and Imaki (in review)
* Support Vector Machine
Biophysical Floodplain Channel Type Model
Methods
Establish channel type reference reaches
Calculate geomorphic characteristics
GIS data preparation(DEM, stream, etc.)
Build a model and predict channel types(Support Vector Machine)
Field measurements
1. Slope2. Bankfull width3. Floodplain width4. Relative shear stress (RSS)5. Fine sediment supply
• Fine sediment• Alpine sediment
6. Root strength / Wood supply
ABC
Flow direction
Pro
file
Reach
RSS+-
Relative shear stress
Braided Island-braided
Meandering Straight
0.00
0.02
0.04
0.06
Slope
Slo
pe(m
/m)
Braided Island-braided
Meandering Straight
0e+0
04e
+06
8e+0
6 Accumulated Precipitation (BFW)
Acc
umm
ulat
ed p
reci
pita
tion
(mm
)
Braided Island-braided
Meandering Straight
050
100
150
Confinement
Cha
nnel
con
finem
ent (
fpw
/bfw
)
Braided Island-braided
Meandering Straight
-200
-100
010
020
0
Relative Shear Stress
Rel
ativ
e sh
ear s
tress
(N/m
2)
Braided Island-braided
Meandering Straight
020
4060
8010
0 Fine Sediment
Fine
sed
imen
t sup
ply
area
(%)
Braided Island-braided
Meandering Straight
05
1015
2025
Alpine SedimentA
lpin
e se
dim
ent s
uppl
y ar
ea (%
)
Columbia River
Grand Ronde
Snake River
N
0 50 km
Prediction accuracy and errorObserved channel type
Pre
dic
ted
cha
nne
l
typ
e
BraidedIsland-
braidedMeandering Straight Total Accuracy
Braided 20 4 0 1 25 80%
Island-braided 1 18 4 4 27 67%
Meandering 1 2 22 2 27 81%
Straight 4 2 0 19 25 76%
Total 26 26 26 26 104
Accuracy 77% 69% 85% 73%
Channel type ~ Slope + acc_precip + r_stress + fine_sediment + alpine_sedimentOverall accuracy = 76% Kappa = 0.69
Coming Soon!