MORPHOLOGICAL RESPONSES OF BEACHES ALONG GALVESTON ISLAND, TEXAS, DURING THE 2003 ATLANTIC HURRICANE SEASON

Galveston Island is a heavily developed and modified transgressive barrier island. Enhanced subsidence due to groundwater withdraw, and response to engineered hard structures including a 22 km long seawall along the east end of the island and installation of Geotubes® along the middle portion of the island has resulted in erosional hot spots with beach retreat as high as 4.6 m/y. Hurricanes strike the Texas coast with a frequency of 0.67 hurricanes per year since 1900. In an effort to investigate morphological response of storms to the various beach settings, eight sites were selected from the west end of the seawall to the middle of the island. Beach profiles were conducted at each during the six-month Atlantic Hurricane season and data were collected four times between July 11, 2003 and November 28, 2003. Hurricane Claudette, a strong Category 1 hurricane that made landfall 165 km southwest of Galveston on July 15th, 2003, had a significant impact on the profile of the gulf beaches on Galveston’s west end. Immediately after the storm the beaches within the study area began to recover, and within four months after the event the shoreline had experienced a moderate, and in some locations significant, recovery. The area of study closest to the seawall exhibited the most pronounced morphological response: greatest sediment loss occurred proximal to the seawall and tapered off toward the west end of the study area. Our data suggests that the presence of Geotubes® caused an amplification of beach lowering and an amplification of erosion “around the ends”. Beach slope was found to be a critical determinant of foredune and vegetation line retreat, while locations without anthropogenic structures showed the least vertical erosion and the narrowest ranges of both erosion and accretion. Beach morphology shows considerable alteration in response to energy fluxes, with primary changes occurring in the backbeach/foredune environments. A draft of this study can be found at http://coastal.tamug.edu.