Downstream Hydrologic and Geomorphic Effects of Large Dams...
Transcript of Downstream Hydrologic and Geomorphic Effects of Large Dams...
![Page 1: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/1.jpg)
William L. Graf
University of South Carolina
Downstream Hydrologic and Geomorphic
Effects of Large Dams
on American Rivers
![Page 2: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/2.jpg)
![Page 3: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/3.jpg)
![Page 4: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/4.jpg)
![Page 5: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/5.jpg)
Research Questions
• What are the hydrologic differences
between unregulated and regulated
river reaches?
• What are the resulting geomorphic
differences between unregulated and
regulated river reaches?
• Why do these differences occur?
![Page 6: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/6.jpg)
![Page 7: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/7.jpg)
![Page 8: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/8.jpg)
![Page 9: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/9.jpg)
Overview
• Previous Research
• Basic Research Strategy and Data
• Methods for Hydrology and Geomorphology
• Results for Hydrology, Geomorphology, and Connections
• Conclusions
![Page 10: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/10.jpg)
![Page 11: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/11.jpg)
![Page 12: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/12.jpg)
Previous Work in this Series
• 1999: census of dams
• 2001: dams and physical integrity
• 2002: SW willow flycatcher case study
• 2002 & 2003: dam removal
• 2005: scientific, social, economic context
• 2006: downstream effects of dams
![Page 13: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/13.jpg)
![Page 14: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/14.jpg)
All Dams > 106 ac ft
Dams in Data Set
![Page 15: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/15.jpg)
Hydrologic Indicators
Annual Max
1-Day Max
30-Day Max
Max Date
Daily Mean
Annual Min
1-Day Min
30-Day Min
Min Date
Annual Range
No. Reversals
Up-Ramp Rate
Down-Ramp Rate
No. High Pulses
High Pulse Duration
No. Low Pulses
Low Pulse Duration
Max/Mean Capacity/Yield
![Page 16: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/16.jpg)
![Page 17: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/17.jpg)
![Page 18: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/18.jpg)
Geomorphic Indicators
• Low Flow Channel
• High Flow Channel
• Low Bars
• High Bars
• Islands
• Active Flood Plains
• Inactive Flood Plains
• Engineered Surfaces
Functional Surfaces
Active Area
Complexity
![Page 19: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/19.jpg)
Unit Active Area
Au = Aa / L / Ad
![Page 20: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/20.jpg)
Complexity Index
Ci = f / Lc
![Page 21: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/21.jpg)
![Page 22: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/22.jpg)
Hydrologic Differences:
Unregulated vs. Regulated
• Annual maximum discharge -67 % *
• 1-day maximum discharge -71 % *
• 30-day maximum discharge -25 % *
• Annual max / Annual mean -60 % *
In Regulated reaches ….
![Page 23: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/23.jpg)
• Annual minimum discharge -33 % *
• 1-day minimum discharge -13 %
• 30-day minimum discharge +52 % *
• Annual min / Annual mean -29 % *
• Annual range of daily flows -60 % *
![Page 24: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/24.jpg)
• Number of reversals +34 % *
• Daily up-ramp rate -60 % *
• Daily down-ramp rate -19 %
• Duration of high pulses +71 % *
• Date of Max (unchanged)
• Date of Min (Aug 13 – Sept 11)
![Page 25: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/25.jpg)
Region Max/Mean Cap/Yield Reduction
East 14.4 0.9 -58 %
Great Plains 21.4 2.8 -65 %
Ozarks 25.4 2.6 -56 %
Pacific NW 3.6 0.5 -19 %
Interior West 11.2 3.2 -67 %
California 15.8 1.9 -58 %
All Regions 16.1 1.9 -58 %
![Page 26: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/26.jpg)
Geomorphic Differences:
Unregulated vs. Regulated
• Low flow channel area +32 % *
• High flow channel area -77 % *
• Low bar area -52 % *
In Regulated reaches ….
![Page 27: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/27.jpg)
• High bar area +7 % *
• Island area -75 % *
• Active flood-plain area -79 % *
• Inactive flood-plain area +363 % *
• Engineered area +145 % *
![Page 28: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/28.jpg)
Regional Diff. Active Area Complexity
East -27 % * -56 % *
Great Plains -91 % * -14 % *
Ozarks -82 % * -39 % *
Pacific NW -43 % * -16 % *
Interior West -65 % * -52 % *
California -64 % * -49 % *
All Regions -72 % -37 %
![Page 29: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/29.jpg)
1936
Jemez River
1980
![Page 30: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/30.jpg)
General Construct
Upstream components
Dam and Releases
Downstream components
![Page 31: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/31.jpg)
![Page 32: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/32.jpg)
![Page 33: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/33.jpg)
![Page 34: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/34.jpg)
1938 1998
Platte River
![Page 35: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/35.jpg)
![Page 36: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/36.jpg)
![Page 37: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/37.jpg)
![Page 38: Downstream Hydrologic and Geomorphic Effects of Large Dams ...rrnw.org/wp-content/uploads/201010869_invited-graf.pdf · •1999: census of dams •2001: dams and physical integrity](https://reader036.fdocuments.us/reader036/viewer/2022071100/5fd8ff1318c6737f50680066/html5/thumbnails/38.jpg)