Hurricane Harvey Flood Sedimentation in Southeastern Texas Coastal Marshes

Authors: Harry Williams*, University of North Texas, Kam-biu Liu, Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA
Topics: Coastal and Marine, Geomorphology, Climatology and Meteorology
Keywords: tropical cyclone, marsh accretion, flood, overwash, washover, rainfall, McFaddin National Wildlife Refuge
Session Type: Paper
Day: 4/3/2019
Start / End Time: 4:30 PM / 6:10 PM
Room: Stones Throw 1 - Granite, Marriott, Lobby Level
Presentation File: No File Uploaded

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 60 inches 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 the magnitude of Hurricane Harvey’s flood sedimentation was weakly controlled by elevation, whereby lower elevations received more sediment, and more strongly controlled by proximity to flood sediment sources, 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. The study provides valuable new information on marsh accretion – a crucial and timely area of inquiry given the threat of submergence posed to coastal marshes by rising sea-levels.

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