Seabed Scouring and Rapid Recovery of the Lower Shoreface and Inner Continental Shelf due to Hurricane Claudette (July 2003), Matagorda Peninsula, Texas

The maximum force of Hurricane Claudette was focused on the mouth of the Colorado River when it made landfall on 15 July, 2003. A geophysical survey was conducted from 27 July to 1 August, 2003 of the lower shore face and inner continental shelf off of the Colorado River. The survey provided a baseline for comparison with subsequent surveys to monitor the recovery of the system over course of twelve months following the storm. Sidescan sonar, Chirp seismic, and multibeam sonar data were collected along with surface sediment and core samples. The survey area extended from the shoreface of Matagorda Peninsula to 3 km offshore in nearly 10 m of water depth. The survey found a 2 km wide band of shore-normal scour depressions and a number of large pits in the surficial Holocene sediment. The pits ranged from 10 to 100 m in diameter, 1 to 2 m deep and the base of the pits contained densely consolidated Pleistocene sediments. The pits were presumably created by strong offshore bottom currents created by the 2m storm surge. The scour depressions were interpreted to be the equivalent of sediment-starved rippled-scour depressions. Follow up surveys were conducted in January 2004 and found much of the scoured and pitted area to be filled with sand. The last survey, conducted one year after Claudette hit found only a mottled surface of mixed sand and mud deposits and little other evidence that the site had been recently hit by a hurricane.