Geomorphic Coastal Change
Resource Brief - March 2009
Importance/Issues
Shoreline change was identified as a vital sign for the Southwest Alaska Network (SWAN) because land loss or gain at the marine edge has important ecological and jurisdictional implications. The physical configuration of the SWAN coastal shoreline is dynamic and constantly changing due to coastal erosion and accretion from natural events, such as storm-driven waves, high tides, nearshore currents, rainfall and runoff, landslides, and earthquakes. Changes in the position of the shoreline affect the composition, relative abundance, and distribution of coastal habitats.
Status and Trends
To evaluate the type of shoreline changes occurring along the 82 km coastline of Lake Clark National Park and Preserve, 7 of 10 cross-shore beach profiles established in 1992 were re-surveyed in 2004 using rod and transit leveling. Cross-shore beach profiles revealed variation in rates of erosion and accretion along the parks coastline. Erosion, landward migration of mean high water (MHW), was observed at 5 cross-shore profiles and accretion, seaward migration of MHW, was observed at 2 profiles. Annual average rates of erosion and accretion ranged from -0.18 to -0.50, and 0.55 to 3.13 m/yr respectively.
Annual rates of erosion and accretion at cross-shore beach profiles, Lake Clark National Park-Cook Inlet Coastline, 1992-2004.
Current and Future Work Efforts
The availability of sufficiently high-resolution geospatial datasets, satellite imagery, and other remote sensing products – now makes it possible to economically and comprehensively quantify shoreline change in space and time. In 2007, Dr. William Manley, Institute of Arctic and Alpine Research (INSTAAR), University of Colorado and the National Park Service selected three priority sites where long-term coastal shoreline change will the analyzed using aerial photography and satellite imagery in Lake Clark National Park and Preserve (1950s through 2006).
