Contrasting Hurricane Ike washover sedimentation and Hurricane Harvey flood sedimentation in a Southeastern Texas coastal marsh

Autor: Kam-biu Liu, Harry F. L. Williams
Rok vydání: 2019
Předmět:
Zdroj: Marine Geology. 417:106011
ISSN: 0025-3227
DOI: 10.1016/j.margeo.2019.106011
Popis: 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.
Databáze: OpenAIRE
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