EROSION EXPOSURE ASSESSMENT OF INFRASTRUCTURE IN ALASKA COASTAL COMMUNITIES.

Alaska communities located along coastlines and tidally influenced rivers are vulnerable to coastal erosion. These communities face decisions that require advance planning, such as implementing shore protection or moving infrastructure. To aid in erosion planning, we estimate erosion exposure for 48 communities from the Bering to the Beaufort seas. We conduct a shoreline change assessment, forecast 60 years of erosion, and estimate the replacement cost of infrastructure in the forecast area. Of 48 communities analyzed, 33 have infrastructure within the erosion forecast area. Fifteen communities comprise 90 percent of the total replacement cost. Eleven of these, and 80 percent of total estimated cost, are in the Yukon-Kuskokwim Delta. More than 40 percent of the estimated cost is forecast to occur by the late 2030s. A summary of findings and map(s) of erosion forecast areas are provided for each community where an assessment could be performed. Erosion forecasts require a clearly identifiable shoreline that can be tracked through time in aerial imagery, as well as no major coastal protection structures in the forecast area. Erosion forecasts are not suitable for 12 communities, so we provide recommendations to address erosion concerns in those community assessment reports. The assessment conducted here is a tool for developing local hazard mitigation plans and strategies to address erosion. There are methodological limitations to linear shoreline change measurements, forecasts, and infrastructure replacement costs. Total costs are not reported in this summary due to these limitations. Users must incorporate expertise and local knowledge when interpreting results. [ABSTRACT FROM AUTHOR]