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