Fluvial Sedementation from Mt. Rainier

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This is the presentation given by Chris Magirl, USGS, at the July 2010 Nisqually River Council Meeting.

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Fluvial Sedementation from Mt. Rainier

  1. 1. Fluvial Sedimentation from Mount Rainier: Impacts on Puget Lowland Rivers Chris Magirl, Jon Czuba, Christiana Barnas, and Frank Voss US Geological Survey, Tacoma, WA
  2. 2. Water and Sediment Loading into Puget Sound <ul><li>Very limited sediment data </li></ul><ul><li>Puyallup system is heavily loaded with sediment </li></ul>
  3. 3. Why the higher loads in the Puyallup, Nooksack, and Skagit?
  4. 5. Prodigious sediment production in Carbon, White, and Nisqually Rivers
  5. 6. Image courtesy National Park Service Nisqually River at Sunshine Point in 2006
  6. 7. White River
  7. 8. <ul><li>~10 m aggradation on the Carbon River in MORA </li></ul><ul><li>Rapid aggradation observed on the Nisqually River </li></ul><ul><li>Debris flows and heavy rainfall mobilizing sediment </li></ul><ul><li>Related to retreating glaciers and rainfall </li></ul>Paul Kennard:
  8. 10. Ed Prych, 1988 Bill Sikonia, 1990 USGS Studies from the 1980s
  9. 11. Tasks: Objectives in studying the Lower Puyallup, White, and Carbon Rivers: <ul><li>Sedimentation trends since 1984 </li></ul><ul><li>Estimate current flood-carrying capacity </li></ul><ul><li>Evaluate effects of selected management options </li></ul><ul><li>Resurvey cross sections measured in 1984 plus more </li></ul><ul><li>Analyze changes in cross sections 1984  2009 </li></ul><ul><li>Analyze aggradation/incision trends at 8 USGS gages </li></ul><ul><li>Analyze channel-conveyance capacity at four USGS gages since the 1980s </li></ul><ul><li>Build hydraulic computer model (HEC-RAS) </li></ul><ul><li>Measure bed-material particle size </li></ul><ul><li>Sediment-transport modeling of management options </li></ul><ul><li>Deliver USGS Scientific Investigations Report </li></ul>Joint Funding Agreement between Pierce County and USGS
  10. 12. Map of the Study Area Including the Puyallup, White, and Carbon Rivers
  11. 16. Bed Elevation Change in the Puyallup River between 1984 and 2009
  12. 17. Bed Elevation Change in the White River between 1984 and 2009
  13. 18. Bed Elevation Change in the Carbon River between 1984 and 2009
  14. 19. Map of the Change in Bed Elevation in the Puyallup, White, and Carbon Rivers
  15. 21. Bed-Material Gradations in the Puyallup, White, and Carbon Rivers
  16. 22. Channel competence to move particles (increasing grain size closer to mountain)
  17. 23. Thalweg Profile in the Puyallup, White, and Carbon Rivers
  18. 24. Carbon River long profile: Carbon Glacier to Commencement Bay
  19. 25. Gage Analysis: Aggradation trends recorded in gaging-station data (12 sites)
  20. 26. Gage Analysis
  21. 27. Gage Analysis
  22. 28. Gage Analysis
  23. 29. Map of the Change in Stage for the 50% Exceedance Flow at USGS Gages
  24. 30. Map of the Variation in Stage for the 50% Exceedance Flow at USGS Gages
  25. 33. HEC-RAS model of river network
  26. 34. Channel-Conveyance Capacity of the Lower Puyallup River
  27. 35. Channel-Conveyance Capacity of the Middle Puyallup River
  28. 36. Channel-Conveyance Capacity of the White River
  29. 37. Major Elements of a Sediment-Transport Model <ul><li>Hydraulic Model </li></ul><ul><li>(Cross Sections, </li></ul><ul><li>Channel Roughness) </li></ul>Hydrology (Flow, Downstream Water-Surface Elev., Water Temperature) Sediment (Bed-Material Size Dist. , Incoming Sediment Load) Sediment Transport Model
  30. 38. Flow Input to the Upper Puyallup River
  31. 39. 5-year Average Annual Sediment Bedload in the Puyallup River
  32. 40. Unanswered Questions: <ul><li>Rate of sediment input to rivers from Mount Rainier and how it is changing in time (Sediment Budget)? </li></ul><ul><li>Is sedimentation rate changing with glacial retreat and larger floods? </li></ul><ul><li>Travel time and quantity of sediment pulses? </li></ul>
  33. 41. Phase II: Fluvial Geomorphology Throughout Watershed <ul><li>Sediment, bathymetry, and topography field data </li></ul><ul><li>Volume of sediment in Alder Lake delta </li></ul><ul><li>Volume of sediment released from Mount Rainier </li></ul><ul><li>Hydraulic (1D) sediment-transport modeling </li></ul><ul><li>Geomorphic response of storm type </li></ul><ul><li>Geomorphology, sediment budget, sediment delivery </li></ul><ul><li>Predict future sedimentation (20-50 yrs) under climate- change scenarios </li></ul>
  34. 42. Conclusions <ul><li>Aggradation downstream from Mount Rainier is significant—impacts on people and habitat </li></ul><ul><li>Complicated response to sediment input </li></ul><ul><li>May be related to climate change—need to track future trends </li></ul>

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