Coordinated, continuous, and compelling shoreline mapping and monitoring to support Alaska communities’ capacity to plan for and mitigate coastal hazards in the face of climate change

Abstract:

Many of Alaska’s coastal communities are increasingly vulnerable to erosion, flooding, and permafrost degradation, however, few vulnerability assessment tools are available to the public at a scale needed for local planning. This presentation outlines the coordinated state and federal mapping efforts that were developed to conduct shoreline change analyses for 47 coastal communities in northern and western Alaska, explores regional differences in shoreline change rates and coastal management practices, and highlights emerging monitoring strategies to support future projections of flooding and erosion hazards. Shoreline datasets were compiled from previously published U.S. Geological Survey assessments for northern Alaska, as well as created from historical and recent aerial images by the Alaska Division of Geological & Geophysical Surveys for western Alaska. Shoreline change rates were calculated every 25 meters along the open coast and tidally influenced river banks from approximately 1950 to 2015. In northern and western Alaska, 53 percent of communities (25 of 47 total) experienced erosion rates greater than 1 meter per year over the past 60 years with erosion rates reaching above 5 meters per year at four communities (Dillingham, Port Heiden, Kaktovik, and Newtok). Shoreline change maps with erosion rates were created in a small map format for community planning and communication with state and federal agencies. Shoreline change rates determined from historical data only provide information on past conditions. Continued monitoring is necessary to quantify recent and future rates of shoreline change, which may be influenced by the construction of coastal protection structures and shifting environmental conditions associated with global climate change.