Collaborative Research: Blowout Dynamics at Cape Cod

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Wind erosion is a widespread process in both coastal and desert environments where sandy substrates are subject to persistent wind action. The most common aeolian dune landform associated with wind erosion in partially to semi-vegetated sandy terrains is a blowout (e.g., a bowl-shaped depression). Research on blowout evolution and morphodynamics is very limited. Dunefield destabilization following some degree of climate change, in many cases, probably starts with blowout development, and our knowledge of how this occurs, the controls exerted by factors such as rainfall and drought, regional wind velocities, vegetation cover, sediment supply and animal/human disturbance is exceptionally poor. Professors Patrick Hesp from the Department of Geography and Anthropology at Louisiana State University and Paul Gares from the Department of Geography at East Carolina University will examine how, and why blowouts are initiated in the Cape Cod region, at what rate blowouts evolve from small to very large forms, what controls the size and morphology of blowouts, what are the thresholds of vegetation cover, wind velocities, surface moisture, and sand wetness that trigger blowout dune development, and control subsequent evolution. A wide range of instruments including cup and sonic anemometers, wind vanes, smoke bombs, sand traps, erosion pins and ground based lidar will be used to measure instantaneous and mean wind velocities, erosion and deposition patterns, and medium term dune changes. An analyses of all aerial photography from the 1940s to present will be conducted to examine dune blowout initiation, seasonal and decadal changes and compare this data with long term climate data to investigate the role of climate in driving dune blowout initiation and development. The data gathered from the aims above will allow a better understanding of (i) the role of climate in blowout initiation and/or stabilization, (ii) the evolutionary stages of saucer and bowl blowouts, and (iii) the typical flow structure and erosional and accretional processes in blowouts of different morphologies. Finally, the data will assist the development of computational and/or physical models of resulting flow and sediment transport dynamics in blowouts, particularly saucer and bowl types.Few studies have ever been conducted on the dynamics of blowouts, yet they are one of the most common aeolian (wind-shaped) landforms in coastal and desert dunefields. This research will provide answers on how and when, and where the blowouts develop. It will improve our understanding of the relationships between climate change and blowout genesis, and will provide a better understanding of how dunes might respond to climate change. It will also improve our understanding of the spatial variation of the turbulent wind flow over complex terrain, and it will contribute to a greater understanding of planetary dune forms. Three graduate students will be trained in aeolian research, geomorphology and instrumentation, and several undergraduate students will be trained in fundamental and applied research techniques. In addition, results will assist management agencies (e.g., Federal parks) because this research will facilitate the development of tools to better manage coast lines, especially in regions experiencing coastal erosion and sea level rise. Results will also be disseminated to the public via a series of posters and booklet on dunes, dune evolution, dune ecology, and the intrinsic value of dunes.