Processing of a Fine Sediment Pulse
after Dam Removal
Sediment Budget and Longitudinal Trends
Chiloquin Dam Removal – Sprague River
Matt Cox, Desiree Tullos, Cara Walter
Background:
Chiloquin Dam
Map: Mike Neumann, USBR
Objectives
• Develop a preliminary sediment budget for
the Chiloquin Dam removal location from pre
removal (2008) to 2 years post removal (2010)
• Examine longitudinal trends in the processing
of the fine sediment pulse.
Methods:
Field Data Collection
Topography/Bathymetry
•2006,2007, 2008, 2009,2010 ADCP
•2008 ,2009 and 2010 GPS RTK
Ground Surveys
Sediment
•riffles - pebble counts
•SSC collected by Klamath Tribes
and USGS
Turbidity, discharge, and stage
USGS gage (#11501000) on the
Sprague River
USGS gage (#11502500) on the
Williamson River
Methods: Discharge, Turbidity, and SSC Sampling
Upstream – USGS Gauge 11501000
Methods:
Estimation of Suspended Sediment Concentration
Turbidity vs. SSC at Sprague River near
Chiloquin (US of reservoir)
N = 66 samples
Turbidity vs. SSC at Williamson River
below Sprague River near Chiloquin
(DS of reservoir)
N = 48 samples
Methods: Reservoir erosion
• Repeat cross sections in
2008, 2009 and 2010
• Volume change calculated
from differences in
reoccupied cross-sections
Methods: Surfacing and GCD uncertainty
1. Difference DEMs
-
2. Filter by uncertainty
3. Filter by spatial
coherence
4. Extract cells of
erosion and
deposition
Wheaton, J. M., Brasington, J., Darby, S. E. and Sear, D. A. (2010), Accounting for
uncertainty in DEMs from repeat topographic surveys: improved sediment budgets.
Earth Surface Processes and Landforms, 35: 136–156. doi: 10.1002/esp.1886
Results:Longitudinal trends in Sediment Deposition
D50 Upstream\D50 Downstream
Results:Longitudinal trends in Sediment Deposition
Results: Reservoir Erosion
WY 2009
WY 2010
Total
Volume evacuated
from Reservoir (m3)
2295
1047
3342
Mass of sediment evacuated from reservoir
(metric tons – r sediment = 1601kg/m3)
3673 (6.8%)
1676 (3.1 %)
5349 (9.9%)
Results : Downstream SSC
Results: Suspended Sediment release during drawdown
and removal
Results: Annual Suspended Sediment Load
Yearly suspended sediment discharge (in metric tons) above and below the site
of the Chiloquin Dam removal
Site
Upstream:
Sprague NR
Chiloquin (USGS
1150100)
Downstream:
Williamson BLW
Sprague NR
Chiloquin (USGS
11502500)
Difference
WY 2008
th
th
(Nov 16 – Sept 30 )
WY 2009
WY 2010
th
st
(Oct 1 to Aug 24 )
During the period of drawdown
and in-stream work
th
(Aug 8 2008 to Aug 20th 2008)
9200
5250
3900
26
9600
7450
5250
73
400
2200
1350
47
Results: Downstream Differenced DEMs
Sprague River Analysis Units
Results: Downstream Net Volume ChangeSprague River Analysis Units
Results: Downstream Differenced DEMs
Williamson River Analysis Units
Results: Net Volume ChangeWilliamson River Analysis Units
Results: Sediment Volume deposited in
Pool Analysis Units
Volume Changes in Sprague and Williamson Pool
Analysis Units (cubic meters)
2008-2009 2008-2010
Pool 1
-48
298
Sprague Pool
Pool 2
60
517
Units
Pool 3
788
3274
Pool 4
27
1352
Williamson Pool
Units
Pool 1
Pool 2
Pool 3
131
-470
-15
1590
1487
829
Chiloquin Dam Removal Sediment
Preliminary Sediment Budget 2008 - 2010
Upstream Boundary
- SSC from turbidity
Downstream Boundary
- SSC from turbidity
DS Deposition
- DEM differencing
Reservoir Erosion
- Volume change from
repeat XS surveys
Conclusions
• Sprague and Williamson Rivers are still processing
the pulse of sediment input by the Chiloquin Dam
Removal.
• Pool filling has been observed in both 2009 and
2010. Very little pool scour was observed.
• Basin wide trends may be partially obscuring the
sediment signal of the removal.
• The suspended sediment signal from the
drawdown event was very small compared to
annual suspended sediment loads.
Future work – Links to Habitat data
• Reach scale habitat and invertebrate data
(EPA EMAP protocol) collected in 2008, 2009
and 2010.
• Movement of endangered fish – USGS
telemetry study ongoing.
Acknowledgements
• Dr. Desiree Tullos
• Cara Walter
• Summer Field Techs
– Greg Woloveke, Kaileen Amish, Ryan Caruso,
Adam Wyborny, Meredith Cavanaugh
Questions?