RAPID: Collaborative Research: Tracking Hurricane Harvey's Storm Surge and Flood Sedimentation

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Category 4 Hurricane Harvey, the most intense wind and rain event to strike Texas in 56 years, made landfall on August 25, 2017, with maximum sustained winds of 130 mph and a storm surge of over 2 m. In addition, the hurricane brought 30-50 inches of rain and caused record-breaking freshwater flooding throughout southeastern Texas, inundating large tracts of coastal marshes with flood waters from rivers and the Gulf of Mexico. Severe freshwater flooding also occurred in inland fluvial wetlands along the Brazos, Trinity, and San Bernard Rivers. Harvey provides an excellent opportunity to study the sedimentary signatures of a rare wind-and-rain event and to estimate its return period by documenting past similar event deposits in the geological record. In addition, there is growing public awareness of the detrimental effects of climate change, particularly in coastal areas threatened by accelerated sea-level rise. This research will help determine whether coastal marshes can survive rising sea-level by providing new information on the role of hurricanes in contributing sediment to marshes, causing accretion and counteracting relative elevation loss due to sea-level rise. This is a collaborative project by research teams at Louisiana State University and the University of North Texas encompassing the complete sedimentary impacts of Hurricane Harvey along a coastal (saltwater)-to-fluvial (freshwater) transect across southeastern Texas.Studies conducted to date suggest that hurricanes are major contributors to marsh growth, with themagnitude of Hurricane sedimentation (millions of metric tons) exceeding annual riverine and coastal sediment inputs, but the topic is still debated. Through marsh coring along the freshwater to marine transect, this study?s main objectives include: (i) documenting the magnitude, character and extent of washover and flood sedimentation in coastal marshes in southeast Texas, and (ii) to measure the magnitude and inland extent of washover sedimentation in the lee of foredune barriers to evaluate whether relatively subtle increases in barrier dimensions can cause substantial reductions in the magnitude of washover sedimentation in marshes. The study will inform coastal management agencies on the use of barriers to block or reduce storm overwash, potentially reducing washover sediment magnitude and inland extent in adjacent marshes, at a time when such sedimentation may be a crucial factor in survivability of marshes in the face of accelerating sea-level rise. This study also aims at producing centuries-to-millennia-long multi-proxy records of hurricane-generated extreme events for southeastern Texas. These long-term records are vital for estimating the return period of such extreme events as Harvey and is critically important for hurricane- and flood-risk assessments and coastal management decision-making.