Hurricane Degradation—Barrier Development Cycles, Northeastern Gulf of Mexico: Landform Evolution and Island Chain History
Hurricane Degradation—Barrier Development Cycles, Northeastern Gulf of Mexico: Landform Evolution and Island Chain History
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飓风退化——墨西哥湾东北部屏障发展周期：地貌演化和岛链历史
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发表时间：
2008
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通讯作者：
G. Carter
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作者：
E. G. Otvos;G. Carter
在约4.0-3.8 ka BP （3.9-3.7 ka 14C）西部搁浅和/或埋藏之前，密西西比-阿拉巴马退性堰洲岛链一直延伸到今天的路易斯安那州东南部。向西的净沿岸漂移、滩涂三角洲和微潮入口绕道在形成细长、狭窄的沙障台地板块方面发挥了重要作用，这些岛屿最初是在这些台地板块上出现的，其中大部分是滩平原地形。相当大的潮下-潮间带护堤盆地的发展，被风暴后出现的冲滩和前海岸护堤山脊所环绕，然后被风暴动员的沙子填满，有助于飓风后的恢复。这些过程与堆积屏障形成的离散阶段有关。日益频繁和破坏性的气旋使岛屿地区减少为横向广泛的潮下屏障平台间隔。在加长的平台板块上，冲积加剧，减少了漂移量，从而减少了岛屿的淤积。船舶航道的加深促进了沙粒从沿海漂流到近海海底地区的流失。这一点和海岸沙通量的明显减少表明自然和人为干扰了漂流供应。海图、航空照片和卫星图像的比较为发生的动态变化提供了定量记录。1916年小布瓦山口的突然拓宽，以及至少9次飓风期间周期性的岛屿减少和磨损，对所有岛屿都产生了决定性的影响。地势低洼的中部和东部（上升流）扇区的裂口造成了长期的岛屿减少。从1965年的贝特西飓风开始，更频繁和更具破坏性的热带气旋导致岛屿面积加速减少。2005年，风、盐的毒性和海水冲过，再加上海岸撤退，严重损害了几个岛屿的植被。由于广泛的低地和狭窄的岛屿区，Ship和Petit Bois是最脆弱的。在1848-49年和2005年之间，它们分别遭受了66%和52%的面积损失。尽管风暴后的恢复是有限的，但东船现在可能濒临灭绝。尽管霍恩岛有较高的残迹海滩山脊、次级沙丘和历史上大量的下漂积，但它也经历了相当大的磨损（23%）。
Abstract Before its western sector was stranded and/or buried ca. 4.0–3.8 ka BP (3.9–3.7 ka 14C), the Mississippi–Alabama chain of regressive barrier islands extended well into present southeastern Louisiana. Westward-directed net littoral drift, ebb-deltas, and microtidal inlet bypassing were instrumental in the formation of elongated, narrow, sandy barrier platform sectors on which these islands, mostly of strandplain topography, have originally emerged. The development of sizable subtidal–intertidal berm basins, ringed by swash and foreshore berm ridges that emerged after storms, then filled by storm-mobilized sand, has aided posthurricane recovery. These processes are linked to discrete stages in aggradational barrier genesis. Increasingly frequent and destructive cyclones reduced island areas to laterally extensive subtidal barrier platform intervals. Enhanced overwash across lengthened platform sectors reduced drift volumes and consequently island progradation. Deepened ship channels facilitated sand loss from littoral drift to offshore seafloor areas. This and the apparent reduction in the longshore sand flux point to natural and human interference with the drift supply. Comparisons of charts, aerial photos, and satellite images provide a quantitative record for the dynamic changes that occurred. Abrupt widening of Petit Bois Pass in 1916 and periodic island diminution and attrition episodes during at least nine hurricanes since had a decisive impact on all the islands. Breaches across low-lying central and eastern (updrift) sectors contributed to long-term island reduction. Starting with Hurricane Betsy (1965), more frequent and destructive tropical cyclones resulted in accelerated island diminution. Damage from wind, salt toxicity, and overwash, combined with shore retreat, seriously impaired the vegetation of several islands in 2005. Because of extensive low and narrow island sectors, Ship and Petit Bois were the most vulnerable. Between 1848–49 and 2005, they suffered 66% and 52% area loss, respectively. Despite recurring but limited post-storm recovery, East Ship now may be approaching extinction. Despite its higher relict beach ridges, secondary dunes, and historically substantial downdrift progradation, even Horn Island has undergone considerable attrition (23%).