Collaborative Research: Blowout Dynamics at Cape Cod

风蚀在沿海和沙漠环境中都是一个普遍的过程，在这些环境中，沙质基质容易受到持续的风的作用。在部分到半植被的沙质地形中，与风蚀有关的最常见的风沙丘陵地貌是井喷(例如，碗状凹陷)。关于井喷演化和地貌动力学的研究非常有限。在许多情况下，在一定程度的气候变化之后的沙地不稳定可能始于井喷发展，而我们对这种情况如何发生的了解，以及由降雨和干旱、区域风速、植被覆盖、沉积物供应和动物/人类干扰等因素施加的控制非常糟糕。路易斯安那州立大学地理与人类学系的Patrick Hesp教授和东卡罗来纳大学地理系的Paul Gares教授将研究如何以及为什么在科德角地区引发井喷，井喷从小到大的演变速度如何，什么控制井喷的大小和形态，引发井喷沙丘发展并控制后续演变的植被覆盖、风速、地表湿度和沙子潮湿的阈值是什么。将使用各种仪器，包括杯式和声波风速计、风叶、烟雾弹、捕沙器、侵蚀钉和地面激光雷达，以测量瞬时和平均风速、侵蚀和沉积模式以及中期沙丘变化。对20世纪40年代至今的所有航空摄影资料进行分析，以考察沙丘喷发的开始、季节和年代际变化，并将这些数据与长期气候资料进行比较，以探讨气候在驱动沙尘喷发和发展中的作用。从上述目标收集的数据将有助于更好地了解(I)气候在井喷开始和/或稳定中的作用，(Ii)碟形和碗形井喷的演化阶段，以及(Iii)不同形态井喷中的典型流动结构和侵蚀和吸积过程。最后，这些数据将有助于建立计算和/或物理模型，以研究井喷产生的水流和泥沙运动动力学，特别是碟型和碗型。关于井喷动力学的研究很少，但它们是海岸和沙漠沙地中最常见的风沙(风形)地貌之一。这项研究将提供井喷如何、何时以及在哪里发展的答案。这将提高我们对气候变化和井喷成因之间的关系的理解，并将更好地理解沙丘可能如何应对气候变化。它还将提高我们对复杂地形上湍流流动的空间变化的理解，并有助于更好地理解行星沙丘的形态。三名研究生将接受风沙研究、地貌学和仪器设备方面的培训，几名本科生将接受基础和应用研究技术方面的培训。此外，成果将有助于管理机构(如联邦公园)，因为这项研究将促进开发更好地管理海岸线的工具，特别是在经历海岸侵蚀和海平面上升的地区。结果还将通过一系列关于沙丘、沙丘演变、沙丘生态和沙丘的内在价值的海报和小册子向公众传播。

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.