Williams, H.F.L. and Denlinger, E. Contribution of Hurricane Ike storm surge sedimentation to long-term aggradation of Southeastern Texas coastal marshes

Hurricane storm surges transport littoral sediment inland and may represent an important mechanism for long-term aggradation of coastal marshes. Hurricane Ike made landfall near Galveston, Texas, on September 13^th 2008, generating a large storm surge that flooded 100 km of coastal marshes in southeastern Texas between Galveston Bay and the Louisiana border at Sabine Pass. The objective of the study was to measure the contribution of the hurricane-derived sediment input to long-term marsh aggradation. A field survey of the storm surge deposit in southeastern Texas coastal marshes was conducted in January 2009 and repeated in January 2010. The results show that the deposit is well-preserved and forms a landward-tapering wedge of sandy to muddy sediments that extends hundreds to thousands of meters inland. Cesium-137 dating was used to estimate decadal-scale sedimentation rates at seven coastal marsh sites positioned along two transects beginning near the coastline and extending inland, aligned with the storm surge direction. Long-term sedimentation rates, including the sediment input from Hurricane Ike, vary from about 0.5 to 1.6 cm/year and decline with distance inland along both transects. The storm surge deposit of Hurricane Ike contributed between 42 % and 73 % of overall sedimentation at these sites in the 58-year period 1950–2008. The study findings suggest that hurricane storm surges may be the predominant mechanism for long-term aggradation of coastal marshes in the study area.