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North to Alaska—an Aerial Shoreline Reconnaissance
Bruce Richmond and Ann Gibbs flew hundreds of kilometers along Alaska's Arctic Ocean coast in August 2006, collecting reconnaissance aerial imagery of the North Slope coastline and barrier islands. The fieldwork was part of the U.S. Geological Survey (USGS)'s National Assessment of Shoreline Change project, a response to chronic beach erosion along U.S. open-ocean shorelines. The weather cooperated well enough for 3 days (August 7-9) of flying, covering approximately 800 km of coastline from the United States-Canadian border to approximately 60 km southwest of Barrow, including both the mainland and barrier-island shorelines. Data were collected from a Cessna 185 Skywagon II floatplane piloted by Jim Webster out of Fairbanks, Alaska. Although some gaps exist because of fog banks and rain, the scientists estimate their total coverage at well over 80 percent. They collected more than 2,500 digital photos and nearly 10 hours of continuous high-definition video imagery of the coast. Using global-positioning-system (GPS) information and Red Hen Systems hardware and software, all the imagery was georeferenced to the aircraft position (approx 1,000 ft offshore and 500 ft above the ground) and integrated into a geographic-information-system (GIS) database.
The photographs can be viewed by using a Google Earth file created by Clint Steele, in which the location of each photograph is plotted on a Google Earth basemap as a dot that is also a link to low- and high-resolution versions of the photograph. To download the file, visit URL http://walrus.wr.usgs.gov/infobank/a/a106ak/html/a-1-06-ak.meta.html, go to the "Google Earth" row near the top of the page, and click on "Download photos."
The field operation was based out of Deadhorse, Alaska, a small town at the end of the Dalton Highway, near Prudhoe Bay and the start of the Trans-Alaska oil pipeline. The town has only a handful of permanent residents (although at any one time there may be 5,000 or more workers in the area) and consists mainly of facilities for the workers and companies that operate at the nearby Prudhoe Bay oil fields. Facilities in Deadhorse are built entirely on manmade gravel pads and most commonly consist of prefabricated trailers brought up by truck, barge, or plane. Highlights include the airport, the general store, and two inns that provide all-you-can-eat buffets twice a day. Because of hazardous working conditions in the Arctic, Deadhorse is a dry (alcohol free) town.
The tidal range along the North Slope coast is small, typically less than 1 ft. The coastal landforms include low-lying, unvegetated sand and gravel barrier islands; tundra bluffs that are 1 to 10 m high and fronted discontinuously by narrow sand and gravel beaches; and broad shallow bays and deltas. Several studies examining historical shoreline change along segments of the Alaskan Arctic Ocean coast have all documented extremely high rates of shoreline retreat—as much as 16 m/yr—with some indication that retreat rates may be accelerating. There is a clear need for a regional study of historical shoreline positions along this coast.
The National Assessment of Shoreline Change project was initiated by the USGS Coastal and Marine Geology Program to provide an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United States and parts of Alaska and Hawaii. A primary goal of this work is to develop standardized methods for mapping and analyzing shoreline movement so that internally consistent updates can periodically be made to record shoreline erosion and accretion. To date, the project has completed analyses for the Gulf of Mexico, the southeast Atlantic coast, and California, with continuing efforts in Hawaii, Oregon, and Washington. USGS colleagues in Alaska encouraged Coastal and Marine Geology Program scientists to begin studies in Alaska, with an initial focus on the North Slope area. The recent fieldwork was part of a new task of the project focusing on the Alaska coastline between the United States-Canadian border and Barrow.
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in this issue:
Aerial Shoreline Reconnaissance of Alaska's North Slope
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U. S. Department of the Interior | U.S. Geological Survey
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