Coastal hazard analyses and projections for Arctic Alaska communities

Abstract

Storms and a changing climate can cause disasters for coastal communities. This is particularly felt in the Arctic, where temperatures are rising faster than the global average and sea ice decline has led to a longer open-water period when storms can make landfall. Communities in western and northern Alaska have experienced decades of frequent flooding and erosion. Climate change is a significant contributor today and for the future, but the current prevalence of disaster loss is more closely related to the continued development within hazard-prone areas. This dissertation maps areas prone to erosion and flooding to provide decision-making products for adaptation planning. Long-term erosion rates are projected 60 years into the future to compute the time until infrastructure is undermined. Flood histories are quantified to map hazard areas and improve storm impact forecasts. Record flood levels are estimated to support floodplain mapping. These studies are primarily exposure analyses that compare existing hazards to existing infrastructure to identify at-risk and safe areas around communities. However, as climate change progresses, existing hazards will change in unanticipated ways. The erosion history of Port Heiden tells an important story about how an unexpected change in coastal barrier islands led to rapid erosion and forced the community to relocate inland. This dissertation fills in the long-standing baseline data gaps about hazards in Arctic Alaska coastal communities. These results will help communities develop outside of hazard prone areas. However, the next iterations of hazard analyses will need to build off this baseline and carefully apply climate-informed approaches to predict changing hazards. Moreover, risk assessments must address community priorities and be improved by incorporating more of the values of mixed subsistence economies common to this region. Through community collaboration, hazard exposure analyses like this dissertation, and improving geophysical models, a roadmap is being built for communities to navigate towards a safer future.