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Erosion Along The Alaskan Beaufort Sea Coast. K. Chelelgo & W. Nyamajeje. Beaufort Sea Coast Map. The Coast’s Geology. Quaternary Sedimentary Permafrost bluffs: Ice Organics Fine-grained sediments Sand & Gravel beaches Unconsolidated bluff at Kenai. Photo by Orson Smith. - PowerPoint PPT Presentation
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Erosion Along The Alaskan Beaufort Sea Coast
K. Chelelgo &W. Nyamajeje
Beaufort Sea Coast Map
The Coast’s Geology
Quaternary Sedimentary Permafrost bluffs:
Ice Organics Fine-grained sediments
Sand & Gravel beaches
Unconsolidated bluff at Kenai. Photo by Orson Smith
Alarming rates of Erosion!• Study area; 40 mile stretch along Beaufort sea• What rates?
• 1955-1979 : 20ft/Yr
• 1979-2,002: 28ft/Yr
• 2002-2007: 45ft/Yr• Causes?
Declining sea ice cover Increase in storm power; wave action Thawing of permafrost Depletion of sediment supply
How it happens
Courtesy of Benjamin Jones, USGS
1. Thawing of Permafrost bluffs 2. Thaw Subsidence of Permafrost Shores
Courtesy of Benjamin Jones, USGSCourtesy of Benjamin Jones, USGS
3. Undercutting of Glacially deposited Bluffs
The Water Wave Action
Impact on Civil Engineering Works
Courtesy of Smith Orson, 2006
Failure of Infrastructure
Structural Solutions1.Revetments
o The shallow slopes provide for wave energy dissipation
Courtesy of Orson Smith
2.Seawalls 3.Bulkheads
Structural Solutions• 4. Offshore Breakwaters
US Army Corps of Engineers photo
Non-Structural SolutionsRetreat Beach Nourishment
Alternative solution; Set-back lines
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