Contrasting Hurricane Ike washover sedimentation and Hurricane Harvey flood sedimentation in a Southeastern Texas coastal marsh
Contrasting Hurricane Ike washover sedimentation and Hurricane Harvey flood sedimentation in a Southeastern Texas coastal marsh
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DOI：
10.1016/j.margeo.2019.106011
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发表时间：
2019-11
期刊：
影响因子：
2.9
通讯作者：
H. Williams;Kam‐biu Liu
中科院分区：
文献类型：
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作者：
H. Williams;Kam‐biu Liu
4级飓风哈维是一场非同寻常的降雨事件。从德克萨斯州中部海岸登陆后，风暴缓慢向东移动，给德克萨斯州东南部地区带来了超过1.5米的降雨量，创下历史纪录。一股巨大的洪水沿着当地的运河和河流倾泻而下，淹没了麦克法丁国家野生动物保护区的沿海沼泽。洪水在沼泽的大部分地区留下了泥泞的洪水存款，沿着沿着横跨避难所的南北向横断面，平均厚度为2.8厘米。飓风艾克（2008年）也在避难所的沼泽中留下了沉积物层，可以直接比较冲刷和洪水沉积物的规模、路径、分布和特征。结果表明，飓风哈维的洪水沉积相当于沼泽中七年的“正常”沉积。这是对沼泽地增生的一个重大贡献，它抵消了由于海平面上升而造成的海拔损失。洪水沉积的模式是弱控制海拔，低海拔地区收到更多的沉积物，更强烈的控制接近洪水沉积物的途径，其中包括从海湾沿岸内水道和沉积物输送到沼泽通过流动通过相互连接的湖泊和池塘的漫滩流。相比之下，飓风艾克的冲刷沉积的规模主要是由接近海湾海岸线。这项研究提供了关于控制沿海沼泽地洪水沉积的规模和分布以及陆地和海洋沉积物来源的作用的宝贵的新资料-鉴于海平面上升对沿海沼泽地造成的淹没威胁，这是一个关键和及时的调查领域。
Category 4 Hurricane Harvey was an extraordinary rain-event. After landfall on the mid-Texas coast, the storm moved slowly to the east, dropping historic amounts of rainfall of more than 1.5 m over Southeastern Texas. A massive pulse of floodwater flowed down local canals and rivers, inundating coastal marshes on the McFaddin National Wildlife Refuge. The floodwaters left a muddy flood deposit over much of the marsh, averaging 2.8 cm in thickness along a north-south transect across the refuge. Hurricane Ike (2008) also left a sediment layer in marshes on the refuge, allowing a direct comparison of magnitude, pathways, distribution and character of the washover and flood deposits. Results suggest that Hurricane Harvey's flood sedimentation was the equivalent of seven years of “normal” sedimentation in the marsh. This is a significant contribution to marsh accretion, which counters elevation loss due to rising sea level. The pattern of flood sedimentation was weakly controlled by elevation, whereby lower elevations received more sediment, and more strongly controlled by proximity to flood sediment pathways, which included overbank flows from the Gulf Intracoastal Water Way and the delivery of sediment into the marsh via flows through interconnected lakes and ponds. In contrast, the magnitude of Hurricane Ike's washover sedimentation was controlled primarily by proximity to the Gulf shoreline. The study provides valuable new information on controls on the magnitude and distribution of flood sedimentation in coastal marshes and the role of terrestrial and marine sediment sources – a crucial and timely area of inquiry given the threat of submergence posed to coastal marshes by rising sea-levels.