Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant...
-
Upload
dorothy-allen -
Category
Documents
-
view
216 -
download
0
Transcript of Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant...
![Page 1: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/1.jpg)
Sediment dynamics in flow-regulated streams and the impact
on aquatic ecosystems
Nira L. SalantDartmouth College
2005Advisors: Carl Renshaw and Frank Magilligan
![Page 2: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/2.jpg)
Impact of dams on ecosystems
- Limited recruitment of riparian species
- Reduced access to floodplain habitat
- Reduced diversity and abundance of benthic fauna
- Decreased productivity of algae and biofilm
![Page 3: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/3.jpg)
O2 N
![Page 4: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/4.jpg)
Purpose
Link the ecological impacts of dams to the geomorphic response resulting from
hydrologic changes
Primary questionsWhat are the geomorphic responses of the
streambed?How can we effectively quantify these
responses?
![Page 5: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/5.jpg)
Overview of methods
Four metrics1. Short-lived fallout radionuclides (7Be, 210Pb)2. Embeddedness measurements3. Long-term hydrologic and morphologic data4. Benthic invertebrates
Three rivers
Regulated: Ompompanoosuc, BlackUnregulated: White
Year-long monitoring
![Page 6: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/6.jpg)
Three inter-connected parts
**Use of fallout radionuclides to quantify sediment transport below dams**
Timescales of stream bed stabilization due to altered flow and sediment regimes below
dams
The effect of substrate stability and sediment deposition on benthic ecology downstream of a flood-control/run-
of-the-river dam
![Page 7: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/7.jpg)
water sediment
Deposition and aggradation Armoring and incision
Ecological changes
DAM
![Page 8: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/8.jpg)
S* vs. T*
From Grant et al. 2003
![Page 9: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/9.jpg)
Deposition and aggradation Armoring and incision
Changes in sediment
residence time and transport
velocity
DAM
![Page 10: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/10.jpg)
Short-lived fallout radionuclides
7Be (t1/2 = 53.4 days) Relative 7Be/210Pb activity
High 7Be/210Pb = “New”
Low 7Be/210Pb = “OldErosion“New”
“Old”
![Page 11: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/11.jpg)
0 2 km
Ompompanoosuc River
ConnecticutRiver
UnionVillageDam
Site 3Site 2.2
Site 2
Site 1
Site 2.1
W. Branch
E . B ran ch
Ve rm on t
Study sites
![Page 12: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/12.jpg)
Union Village Dam
![Page 13: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/13.jpg)
0
5
1 0
1 5
2 0
2 5
3 0
3 5
0
0 . 2
0 . 4
0 . 6
0 . 8
1
1 . 2
5 0 1 0 0 15 0 2 0 0
Level of flood-control gates compared to hydrograph
![Page 14: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/14.jpg)
0
5
1 0
1 5
2 0
2 5
3 0
3 5
0
0 . 2
0 . 4
0 . 6
0 . 8
1
1 . 2
5 0 1 0 0 15 0 2 0 0
Level of flood-control gates compared to hydrograph
Highly regulatedHigh flow
![Page 15: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/15.jpg)
0
5
1 0
1 5
2 0
2 5
3 0
3 5
0
0 . 2
0 . 4
0 . 6
0 . 8
1
1 . 2
5 0 1 0 0 15 0 2 0 0
Level of flood-control gates compared to hydrograph
Partially regulatedHigh flow
![Page 16: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/16.jpg)
0
5
1 0
1 5
2 0
2 5
3 0
3 5
0
0 . 2
0 . 4
0 . 6
0 . 8
1
1 . 2
5 0 1 0 0 15 0 2 0 0
Level of flood-control gates compared to hydrograph
UnregulatedLow flow
![Page 17: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/17.jpg)
Bed sediment samplingMonthly sampling February to July 2004
![Page 18: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/18.jpg)
Samples dried, sieved and counted for 7Be activity
![Page 19: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/19.jpg)
0
5
1 0
1 5
2 0
2 5
3 0
3 5
0
0 . 2
0 . 4
0 . 6
0 . 8
1
1 . 2
5 0 1 0 0 15 0 2 0 0
Highly regulatedHigh flow
![Page 20: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/20.jpg)
Highly regulated flow: Early spring
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
50 60 70 80 90 100 110 120
Below dam (Site 3)
Midstream (Site 2)
Downstream (Site 1)
Julian day
![Page 21: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/21.jpg)
Highly regulated flow: Early spring
80 90 100 110 120 130 1400
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Julian day
Below dam (Site 3)
Midstream (Site 2)
Downstream (Site 1)
![Page 22: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/22.jpg)
0
5
1 0
1 5
2 0
2 5
3 0
3 5
0
0 . 2
0 . 4
0 . 6
0 . 8
1
1 . 2
5 0 1 0 0 15 0 2 0 0
Partially regulatedHigh flow
![Page 23: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/23.jpg)
0 2 km
Ompompanoosuc River
ConnecticutRiver
UnionVillageDam
Site 3Site 2.2
Site 2
Site 1
Site 2.1
W. Branch
E . B ran ch
Ve rm on t
Study sites
![Page 24: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/24.jpg)
Partially regulated flow: Mid-spring
130 135 140 145 150 155Julian day
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Below dam (Site 3)
Midstream (Site 2)
Downstream (Site 1)
Below dam (Site 2.2)Midstream (Site 2.1)
![Page 25: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/25.jpg)
Entire time period
50 100 150 2000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0
0.2
0.4
0.6
0.8
1
1.2
Below dam (Site 3)
Midstream (Site 2)Downstream (Site 1)
Below dam (Site 2.2)
Midstream (Site 2.1)
![Page 26: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/26.jpg)
Measured transport velocities
Time period 7Be velocity (m/d)
Early spring: 31 March – 14 May 40 – 60
Mid-spring: 31 March – 28 May 40 – 60
Late spring: 28 May – 18 June • below dam • downstream
30 – 6060 – 80
![Page 27: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/27.jpg)
Comparisons to previous studiesSediment transport rates
Material Velocity (m/d) Source
Bed load 0.3 – 4.5 m/d Beechie (2001)
Bed load 30 – 80 m/d This study
Suspended load 600 – 1500 m/d Bonniwell (1999)
![Page 28: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/28.jpg)
Effect of grain size interactions on transport
![Page 29: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/29.jpg)
Dates 7Be velocity
One-fraction velocity
Two-fraction velocity Sand | Gravel
Sand fraction (Fs)
31 March – 14 May 40 – 60 9200 39 – 59 0.62- 0.8 0.099 - 0.10
31 March – 28 May 40 – 60 9000 36 – 62 0.62-0.8 0.099 - 0.10
28 May – 18 June • below dam • downstream
30 – 6060 – 80
5500 33 - 6060 – 75
0.44 – 0.800.80 – 1.0
0.14 - 0.150.15
Comparisons to previous studiesSediment transport models
![Page 30: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/30.jpg)
Timescales of stream bed stabilization due to altered flow and sediment regimes below dams
Pre-dam Post-dam
-0 .2
0
0 .2
0 .4
0 .6
0 .8
1
1 .2
19 45 19 5 1 1 9 57 19 63 1 96 9 1 97 5 1 9 91
0
0 .2
0 .4
0 .6
0 .8
1
1 .2
1 94 5 1 954 196 3 19 82 1 99 1
Y ear1 9 36-0 .2
Ompompanoosuc River- Sediment over-
supply
Black River- Sediment limitation
![Page 31: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/31.jpg)
0
0.2
0.4
0.6
0.8
1
1.2
Pre Post 1 Post 2 Post 3 Post 4
OmpompanoosucBlack
Decade
Timescales of bed elevation stabilization
Bed elevation variance
![Page 32: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/32.jpg)
Black RiverImmediate stabilization
![Page 33: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/33.jpg)
Ompompanoosuc RiverGradual stabilization
![Page 34: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/34.jpg)
Benthic ecology
Lack of disturbance Sediment deposition
![Page 35: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/35.jpg)
Family Date Regulated Unregulated P
Hydropsychidae July 39.8 10.9 0.008
Hydropsychidae September 57.8 14.2 < 0.001
Ephemerellidae July 8.7 10.9 < 0.001
Ephemerellidae September 16.8 22.9 < 0.001
Results
![Page 36: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/36.jpg)
Conclusions
Radionuclides offer a simple and effective method for directly measuring transport rates
Dams and their specific operation control the geomorphic response of the streambed
Geomorphic changes to the streambed drive changes to benthic ecology
![Page 37: Sediment dynamics in flow-regulated streams and the impact on aquatic ecosystems Nira L. Salant Dartmouth College 2005 Advisors: Carl Renshaw and Frank.](https://reader035.fdocuments.us/reader035/viewer/2022062516/56649e495503460f94b3c981/html5/thumbnails/37.jpg)
Acknowledgements
Funding
National Science Foundation
Arthur D. Howard Award
(GSA QG&G)
Vermont Geological Society
Dartmouth College Earth Sciences
Hydrologic records/ dam information
Greg Hanlon and Thomas Snow
(U.S. Army Corps of Engineers)
Ken Toppin (USGS)
Biological assistance Jeffrey Veikko Ojala
(USDA Forest Service)Scott Wixsom and Dan Mckinley
(USFS Green Mountain National Forest)Craig Layne and Darren Ward
(Dartmouth Department of Biology)Kaoru ItakuraRebecca KrystosekJulie Jo Walters
Field assistance Kelly Sennatt and Alexandra Fleming
(Dartmouth Department of Earth Sciences).
Thank you Frank and Carl!
Also thanks to Jim Kaste, Keith Nislow, and Brian Dade for their advice and assistance