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Sediment Transport Following
Dam Removal:Prediction, Interpretation, and Comparison
between Observation and Prediction
Yantao Cui1, Ethan Bell1, John Wooster1, Jen Aspittle1, Bruce Orr1, Frank Ligon1, Andrew
Wilcox2, and Jen Vick3
1. Stillwater Sciences, 2855 Telegraph Ave., Suite 400, Berkeley, CA 94705
2. Department of Geosciences, University of Montana, Missoula, MT 59812
3. Consultant, 416 Perry Avenue, Pacifica, CA 94044
RRNW Symposium 2010, Stevenson, WA
Sediment Pulse in Rivers
Dam removal will generally result in a sediment
pulse in the hosting river
Tom Lisle, Jim Pizzuto and others (1997): dispersion
dominates pulse evolution
Gary Parker, Tom Lisle, Jim Pizzuto and Yantao Cui
subsequently developed sediment transport models
to simulate sediment pulses in rivers
Simulated Sediment Pulse Evolution(Cui and Parker 2005)
time 0 Note: diagrams are vertically
exaggerated 150 times.
time 0The formation of
the deltaic deposittime 1
The deltaic deposit
grows larger
time 1
time 2
The deltaic deposit
joins the pulse
time 2
time 3
The deltaic deposit becomes part of the
sediment pulsetime 3
time 4
Sediment Pulse due to Mining Waste
Disposal, Paula New Guinea (Cui and
Parker 1999)
-1
0
1
2
3
4
5
6
7
8
1985 1987 1989 1991 1993 1995 1997Year
Change in B
ed E
levation (
m)
Konkonda
Kuambit
Dashed lines with symbols are field measurements; solid
lines are from numerical simulation.
Navarro River Landslide
-5
-4
-3
-2
-1
0
1
2
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Distance (km)
Net
Ch
an
ge
in
Be
d E
leva
tio
n (
m)
1995 to 1996, simulation
1995 to 1996, measurement
1995 to 1997, simulation
1995 to 1997, measurement
c). Comparison of net change in bed elevation
Adaptation of Sediment Pulse Model
for Dam Removal
Soda Springs Dam, North Umpqua River, Oregon
Marmot Dam, Sandy River, Oregon
Saeltzer Dam, Clear Creek, California
Dam Removal Express Assessment Models
(DREAM) (Cui, Braudrick, Parker, Cluer, Dietrich 2006)
Dams on the Klamath River, CA and OR
Simkins and Bloede dams, Patapsco River, MD
Marmot Dam, Sandy River, OR
Model Prediction in 1999
Rapid initial erosion of reservoir deposit Channel gradient reduces to <2% within 5 days
Despite the rapid initial erosion, it would take several years to erode most of the deposit out of the reservoir area
Downstream sediment deposition would be limited to within a couple of miles downstream of the dam, plus isolated locations while the majority of the river reach experiences little deposition
Increase in TSS would be low – relatively low spikes on the 1st day and during storm events
Sand would deposit only near river mouth
No head-cut would occur, and knickpoint migration would be a smooth one
Example of the
formation of a “head-
cut” following Maple
Gulch Dam removal,
Evens Creek, OR,
courtesy of Greg
Stewart.
Marmot Impoundment Area: Year 1
-9
-7
-5
-3
-1
1
00.511.522.5
Distance Upstream from Marmot Dam (km)
Ch
an
ge in
Avera
ge
Bed
Ele
vati
on
(m
)
Flow direction
Dry
Average
Wet
(a). 2008 (one year following dam removal)
Marmot Impoundment Area: Year 2
-9
-7
-5
-3
-1
1
00.511.522.5
Distance Upstream from Marmot Dam (km)
Ch
an
ge in
Avera
ge
Bed
Ele
vati
on
(m
)
Flow direction
Dry
Average
Wet
(b). 2009 (two years following dam removal)
Depositional Wedge d/s Dam: Year 1
-1
0
1
2
3
4
5
0 0.3 0.6 0.9 1.2 1.5 1.8
Distance Downstream from Marmot Dam (km)
Ch
an
ge in
Avera
ge
Bed
Ele
vati
on
(m
)
Average
Dry
Wet
Flow direction
(a). 2008 (one year following dam removal)
Depositional Wedge d/s Dam: Year 2
-1
0
1
2
3
4
5
0 0.3 0.6 0.9 1.2 1.5 1.8
Distance Downstream from Marmot Dam (km)
Ch
an
ge in
Avera
ge
Bed
Ele
vati
on
(m
)
Average
Dry
Wet
Flow direction
(b). 2009 (two years following dam removal)
-1
0
1
2
3
4
5
0 5 10 15 20 25 30 35 40 45
Distance Downstream from Marmot Dam (km)
Ch
an
ge
in
Av
era
ge
Be
d
Ele
va
tio
n (
m)
Prediction that used discharge from an average year as input
Prediction that used discharge from a dry year as model input
Prediction that used discharge from a wet year as model input
Field measurement by Portland General Electric
Flow direction(b). 2009 (two years following dam removal)
-1
0
1
2
3
4
5
0 5 10 15 20 25 30 35 40 45
Distance Downstream from Marmot Dam (km)
Ch
an
ge
in
Av
era
ge
Be
d
Ele
va
tio
n (
m)
Prediction that used discharge from an average year as input
Prediction that used discharge from a dry year as model input
Prediction that used discharge from a wet year as model input
Field measurement by Portland General Electric
Flow direction(a). 2008 (one year following dam removal)
1-D numerical modeling
2/3-D numerical modeling
Physical modeling
Discussion
1-D modeling will remain as the main workhorse
for dam removal sediment transport studies due
to the large spatial and temporal scales involved.
Project Area
Dams on the Klamath River
Dennis Gathard
Using existing
bottom outlet for
drawdown
Blast open a
bottom outlet and
install a gate for
controlled release and
drawdown
Iron Gate Dam
Copco 1 Dam
Copco 2 Dam
J.C. Boyle Dam
Dams on the Klamath River
~ 20 million cubic yards of sediment deposits
with high water content
mostly silt-sized material
Release of the sediment during/following dam
removal results in
minimal sediment deposition downstream
high suspended sediment concentration that
decreases in the downstream direction
Biological Impacts
Impacts greatest on species and life stages distributed
mainly in the upper mainstem Klamath River during
winter and spring peaks
Spatial distribution and life history variability are keys to
avoiding impacts
Populations of all species are expected to recover in the
long-term
Measures are recommended to support the survival of
individuals and populations in the short-term