National Assessment of Shoreline Change Project, Alaska

Primary contact(s): Bruce Richmond, (831) 427-4731, brichmond@usgs.gov; Ann Gibbs, agibbs@usgs.gov, (831) 427-4740

Status: Ongoing

Project area: The study will initially focus on the north-slope region from the Canadian border to Barrow Peninsula.

Description: Beach erosion is a chronic problem along most open-ocean shores of the United States. As coastal populations continue to grow, and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding past and present shoreline changes. There is also need for a comprehensive analysis of shoreline movement that is regionally consistent. To meet these national needs, the Coastal and Marine Geology Program of the U.S. Geological Survey (USGS) is conducting 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.

Why: Three separate and independent studies examining historical shoreline change along segments of the Alaskan Arctic Ocean coast (north slope) have all documented extremely high rates of shoreline retreat. A) Reimnitz and others (1988) compared National Oceanographic Survey (NOS) charts from 1951 and 1983 for the Beaufort Sea coast from the Colville River delta to Drew Point. They measured average erosion rates up to 16 m/yr with large sections of coast ranging between 5 and 10 m/yr. They also measured accretion near the Colville River delta of +20 m/yr. Bill Manley and others from INSTAAR (Boulder, Colorado) have recently documented shoreline change near Barrow using orthorectified 1955 black and white aerial photographs and 2002 ORRI (orthorectified radar imagery). They measured shoreline retreat rates up to 8 m/yr for the mainland coast and up to 16 m/yr for the barrier islands. C) Mars, Houseknecht, and Garrity (USGS, 2006) examined coastal change in the northeastern NPRA (National Petroleum Reserve - Alaska) using 1955 USGS 1:250,000 topographic maps and 1985 and 2005 Landsat 5 imagery. They measured an increase in the average rate of coastal land loss for the two time periods examined: 1955-1985 = 0.5 km2/yr; 1985-2005 = 1.1 km2/yr. All three studies clearly show high rates of coastal change along north-slope shorelines with some indication that the rates of retreat may be accelerating. There is a clear need for a regional study of historical shoreline positions using the approach developed for other parts of the country.

Audience: The north coast of Alaska effort is notably important for several reasons: (1) immense federal land holdings including the NPRA and ANWR; (2) important pending land-use decisions; (3) unique, sensitive and stressed ecosystems, (4) vulnerability of sparse coastal infrastructure; (5) some of the highest shoreline change rates in the world; and (6) large influence of important climate-change phenomena, such as the presence of sea ice and the rate and timing of its advance and retreat, permafrost stability, land subsidence and sea-level rise, on coastal stability.

Cooperators: Bill Manley and Leanne Lestak, University of Colorado, INSTAAR; Carl Markon and Ben Jones, USGS Alaska Science Center.

Keywords: coastal erosion, beach loss, North Slope, arctic coasts, Alaska shoreline retreat, historical shoreline assessment

Start Date: October 1, 2006

End Date: Ongoing

Geographic Bounding Box:

   Upper Left (Lat/Long): 71.42,-157

   Lower Right (Lat/Long): 69.55,-141

Project Link: http://walrus.wr.usgs.gov/infobank/programs/html/regions2idshtml/ak_ids.html