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，沙质基材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成沙丘地貌是井喷（例如，碗状洼地）。对井喷演化和形态动力学的研究非常有限。在许多情况下，随着一定程度的气候变化，杜内菲尔德不稳定可能始于井喷开发，我们对这种情况如何发生的了解，降雨和干旱、区域风速、植被覆盖、沉积物供应和动物/人类干扰等因素的控制作用非常差。路易斯安那州立大学地理与人类学系的Patrick Hesp教授和东卡罗莱纳大学地理学系的Paul Gares教授将研究在科德角地区井喷是如何以及为什么开始的，井喷从小到非常大的形式以什么速度演变，是什么控制了井喷的大小和形态，植被覆盖的阈值是什么，风速，表面湿度，而沙的湿度则触发了沙丘的发展，并控制了随后的演变。包括杯形和声速计、风标、烟雾弹、沙坑、侵蚀销钉和地面激光雷达在内的各种仪器将用于测量瞬时和平均风速、侵蚀和沉积模式以及中期沙丘变化。将对20世纪40年代至今的所有航空摄影进行分析，以检查沙丘爆裂的发生、季节和年代际变化，并将这些数据与长期气候数据进行比较，以调查气候在推动沙丘爆裂的发生和发展方面的作用。从上述目标中收集的数据将有助于更好地理解(i)气候在井喷开始和/或稳定中的作用，（ii）碟状和碗状井喷的演化阶段，以及（iii）不同形态井喷的典型流动结构和侵蚀和增加过程。最后，这些数据将有助于开发井喷，特别是碟状和碗状井喷中产生的流动和沉积物输运动力学的计算和/或物理模型。很少有关于井喷动力学的研究，但它们是沿海和沙漠沙丘地带最常见的风成地貌之一。这项研究将提供井喷如何、何时以及在何处发生的答案。它将提高我们对气候变化和井喷成因之间关系的理解，并将更好地了解沙丘如何应对气候变化。它还将提高我们对复杂地形上湍流气流空间变化的理解，并有助于更好地理解行星沙丘的形式。三名研究生将接受风沙研究、地貌学和仪器仪表方面的培训，几名本科生将接受基础和应用研究技术方面的培训。此外，研究结果将有助于管理机构（例如，联邦公园），因为这项研究将有助于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。研究结果亦会透过一系列有关沙丘、沙丘演变、沙丘生态及沙丘内在价值的海报及小册子向市民发放。

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.