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