Coastal Erosion Responses for Alaska - the National Sea Grant ...

20.11.2013 Views
Mason—Living with the Coast of Alaska Revisited islands are ubiquitous on much of the East Coast and suffer from repeated storms, hurricane force winds, and storm surge. Large-scale development of the coast (e.g., Atlantic City, Bogue Bay, or Pensacola) over the last century has fostered and conditioned the engineering solutions to nature’s challenges. Once the terrestrial frontier was closed, the Army and its Corps of Engineers turned to block the sea. Similar operations were conducted on the eastern rivers, especially during the progressive decades of the 1930s and 1940s. In a struggle worthy of America’s Manifest Destiny, engineers launched one of the greatest efforts to contain nature, straightening rivers, heightening levees, blocking inlets, exhuming and filling marshes. A number of geomorphologists argue that Hurricane Katrina is Nature’s payback and even suggest refilling the marshes and allowing the Mississippi its will. Alaska presented a considerable challenge as a subject for the coastal hazards treatment developed by Pilkey at Duke University. Virtually no coastal community in Alaska was hazard-free. In fact, Barrow, only subject to bluff erosion and storm surge, seemed the safest place to live! The threats to life and limb were most severe in Seward ranging from imminent tsunami up Resurrection Bay, flooding from several sources, including temporary snow dams above town, and earthquake. Equally ominous threats face Anchorage, Homer, Juneau, Kodiak, Valdez, and Sitka. Who could sleep at night in Alaska if aware of the underlying hazards? I would love to live downtown but geologicinduced guilt keeps me away. In fact, Orrin once commented that if the series had started with Alaska, the problems of the East Coast would not have even warranted a look, by comparison. One topic is largely missing from the first edition of the book: Global Change. In the last decade, anthropogenic global change, greenhouse warming, etc., has outpaced any other public awareness of the natural world. Too often the debate over Global Change is fueled by anecdotal accounts which frequently wend their way into public policy. For example, in 2004 the Government Accounting Office pronounced that nearly 40 m (>120 ft) erosion had afflicted Shishmaref in one single storm in 1997. Until the Army Corps study, no such documentation has existed. The source for such rates of change is likely the anecdotal accounts in the press; for example, my examination of the Anchorage Daily News from 1997 to 2004 indicates the routine erosion of 10 m (30 ft) of bluff. However, a comparison of photos from 1992 to 2004 shows a different story. But in order to know Global Change, we need a baseline— climate records extend barely 100 years. Several efforts are on the horizon to tackle this mission: Bill Manley and a host of others have signed on with the Arctic Coastal Monitoring program headed by Diane Sanzone of the National Park Service; the product will be a photogrammetric documentation of erosion in Kotzebue Sound and to ground truth these interpretations in the field.

Coastal Erosion Responses for Alaska: Workshop Proceedings One huge complication is the possibility that we have entered a “no-analog” situation in relation to the effects of greenhouse warming—a time like no other in recent earth history. Why? Because the geologic record in the north, and I include the Atlantic, indicates that storms were stronger and more powerful during the Little Ice Age (and other cold periods), owing to the heightened contrasts between a colder Arctic and the tropics. Some of the LIA North Sea storms in the 1500s-1700s were awesome, flooding the Netherlands and Britain. Evidence of stronger storms can be found in northern Alaska, as well. In 1884 Capt. Hooper commented on the ferocity of northerly storms that routinely pummeled the Yukon Delta during winter, scattering ice blocks well inland. Nothing like this has occurred in the last generation. The barrier islands around Shishmaref also show evidence of hurricane force storms that cut wash-around channels into the islands, landforms reminiscent of hurricane effects on Padre Island, Texas. Again, the recent spate of storms has not reached such extremes. That is why we need to exercise caution in extrapolating about global change from the effects of storms on developed shorelines such as Shishmaref or Barrow or Nome So, moving counter-clockwise around the Alaska coast, I will discuss the principal problem areas from Kaktovik to Unalakleet, followed by a leap to the Kenai Peninsula, deferring discussion of Anchorage to others. As we consider bluff erosion, let’s pause to examine the processes that operate on permafrost bluffs, most of which are seen in more temperate zones, as well. Four principal processes undermine a bluff. (a) Waves can cut a niche into the frozen bluff and remove material; depending on the length of wave action and the carving distance, a very sizable block can collapse. (b) Slope wash from the top. (c) Melt-out of ice bodies causes slump—high rainfall can do something similar. And (d) channelized flow in gullies. Quite possibly, global warming will mean that as permafrost-laden bluffs warm, thermoniching will be less frequent and melt-out will be more frequent. Coastal protection measures have a lengthy history on the North Slope, the legacy of the humble 55 gallon fuel drum, discarded on the ice and tundra by the thousands after 1945. The 55 gallon drum lends itself to use as shoreline protection; it was used in the earliest efforts at Kaktovik, Barrow, Shishmaref, and Kotzebue. Another legacy of the Cold War years is the frequent placement of dump facilities adjacent to eroding shorelines: convenience more than logic or awareness of geomorphic process explains this “decision” making. Several communities continue to defend dumps: Kaktovik, Barrow, Kotzebue, and Dillingham. Kaktovik (pop. 400) is situated on Barter Island, composed both of residual Pleistocene “mainland” and an eroded and re-deposited gravel spit.

Page 1 and 2: Coastal Erosion Responses for Alask

Page 3: Contents Introduction Orson P. Smit

Page 6 and 7: Smith—Introduction Inherent in th

Page 10 and 11: Mason—Living with the Coast of Al

Page 12 and 13: Mason—Living with the Coast of Al

Page 14 and 15: 10 Mason—Living with the Coast of






Page 27: Coastal Erosion Responses for Alask

Page 30 and 31: 26 Atkinson—Ice, Wind, Waves, and

Page 32 and 33: 28 Atkinson—Ice, Wind, Waves, and

Page 34 and 35: 30 Miller—Management Responses to



Page 40 and 41: 36 Bates—State and Coastal Distri






Page 54 and 55: 50 Ruggiero—Coastal Sediment Budg

Page 56 and 57: 52 Ruggiero—Coastal Sediment Budg







Page 72 and 73: 68 Zufelt and Smith—Arctic and Lo

Page 74 and 75: 70 Zufelt and Smith—Arctic and Lo

Page 76 and 77: Coastal Erosion Books/DVD Published

coastal

erosion

alaska

shoreline

responses

shore

workshop

proceedings

engineering

structures

nsgl.gso.uri.edu

Coastal Erosion Responses for Alaska - the National Sea Grant ...

Coastal Erosion Responses for Alaska - the National Sea Grant ... ... View more Coastal Erosion Responses for Alaska - the National Sea Grant ...

Delete template?

Save as template ?

Coastal Erosion Responses for Alaska - the National Sea Grant ... Coastal Erosion Responses for Alaska - the National Sea Grant ...