Hurricane Storm Surge Sedimentation on East Texas Gulf Coast Marshes: Spatial Variations in Sediment Distribution in the Right-Front Quadrant of Hurricane Ike
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Hurricanes are well known for producing catastrophic devastation to both natural and human environments along the northern Gulf of Mexico coastline. Hurricane Ike made landfall on the eastern tip of Galveston Island, Texas, on 13 September 2008, and the region in the right-front quadrant of the storm experienced catastrophic storm surge flooding. This study investigates spatial variations in sediment distribution on McFaddin National Wildlife Refuge, which is located in the geographic region that was impacted by the right-front quadrant of Hurricane Ike. Fieldwork conducted in summer 2017 and summer 2018 involved digging shallow pits on four transects between Sabine Pass, Texas, and High Island, Texas. Eight pit sites were established on Transect 1, the easternmost transect, and six pit sites each were established on Transects 2, 3, and 4, with Transect 4 located farthest west. All four transects extend 880-1630 meters, with pit sites beginning near the coastline and extending landward. Elevations were measured at each pit site along all four transects using a telescopic level and stadia rod. Results obtained in the field indicate that the Hurricane Ike sediment deposit has been found on all four transects, and that the deposits decrease in thickness moving landward along each transect. On Transect 1, at Pit Site 1, the thickness of the Hurricane Ike deposit was 61 centimeters; this same deposit gradually tapers down to a thickness of 4 centimeters at Pit Site 8. On Transect 4, Pit Site 1 had a sediment thickness of 53 centimeters, whereas at Pit Site 6 the deposit was 5 centimeters thick. Additionally, there is evidence that sedimentation has been impacted by the presence of man-made levees that lie perpendicular to the Gulf Coast at Transects 2, 3, and 4.
Furthermore, the observational results of this study were used in Regression Analyses to model hurricane storm surge sediment deposit thickness based on pit site distance inland, pit site elevation, and distance from the landfall of Hurricane Ike. Moreover, Analysis of Variance revealed whether distance inland, distance from landfall location, and the interaction between distance inland and distance from landfall location had any significant effect on storm surge deposit thickness. Actual sediment deposit thicknesses measured in the field were compared to the Regression and Analysis of Variance results. Results show that the Power Law Curve from the Regression Analyses was the most robust predictor of pit site sediment thickness based on distance inland, with an R2 value of 0.538. Additionally, the Regression and Analysis of Variance results revealed that transect distance from the landfall location of Hurricane Ike was the only independent variable that could not predict or explain storm surge deposit thickness.
The goal of this study was to discover spatial variations in storm surge sedimentation in the geographic region impacted by the right-front quadrant of Hurricane Ike. The findings of this study provide improved understanding of the spatial relationship between storm surge sedimentation and storm surge heights, valuable knowledge about the sedimentary response of coastal marshes subject to storm surge deposition, and useful guidance to public policy aimed at combating the effects of sea-level rise on coastal marshes along the northern Gulf of Mexico coastline.