Collaborative Research: Coastal Geomorphic Consequences of Wave Climate Change

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Collaborative Research: Coastal Geomorphic Consequences Of Wave Climate Change Adams, McNamara, Moore, MurrayThe potential effects of sea-level rise, associated with global climate change, have been widely publicized. However, shoreline change is also influenced by changes in ocean storminess and the resulting deep-water wave field. Changes in the statistical distribution of heights, periods, and directions of storm-generated waves will affect wave-driven longshore sediment transport, driving rapid adjustment of coastline shape through shoreline retreat (erosion) in some places and shoreline advance (accretion) in others. The goal of this project is to improve our understanding of sandy coast shoreline response to a series of storm-climate-change scenarios over a range of shelf morphologies. The scope of this project can be summarized as a series of specific questions: How do variations in storminess interact with continental shelf bathymetry to reconfigure coastal planforms? What are the magnitudes and patterns of coastal morphologic responses that can be expected from the shifts in wave climate that have already occurred in recent decades? Can we already detect such responses? What large-scale shoreline configurations are most vulnerable to increased erosion in the future? This project will employ numerical modeling of wave transformation (shoaling and refraction) and longshore sediment transport to explore a range of wave climate and continental shelf scenarios. Previous numerical modeling efforts have aided our understanding of large-scale coastal evolution, but relied on simple assumptions regarding wave transformation. These simple assumptions may bring into question the degree to which previous model results can be related to actual coastlines. By incorporating more sophisticated numerical treatments of wave/shelf interactions, this project should provide improved accuracy in projections of locations and magnitudes of coastal erosion and accretion. Analysis of historical shoreline-change patterns will both evaluate how select coastlines might already be responding to changes in storm behaviors, and will test which combinations of model components best reproduce observations. Results will help evaluate the response of sensitive coastline types to scenarios of future storm and wave-climate changes.Global climate change may alter ocean wave conditions thereby leading to changes in coastline shapes. This research will address the impacts of wave climate change on patterns of coastal erosion for a wide range of continental shelves. By incorporating state-of-the-art wave models, which calculate how waves redistribute their energy as they approach shore, into a pre-existing computer model of shoreline-change, we will determine the types of coasts that are most likely to change severely for a range of possible climate scenarios. Historical shoreline-change information will be used to document coastal reconfiguration already in progress, and to evaluate computer model performance. Results of this project will help to inform residents, developers, policy makers, scientists, engineers, and other stakeholders as they make decisions about the management of coastal regions.