ABSTRACT

Hurricane Alicia made landfall on Aug. 18, 1983, on the eastern end of Follets Island just west of San Luis Pass and Galveston Island. The maximum winds (198 km/hr, 115 mph), storm surge (390 cm, 12.7 ft), and wave energy were concentrated just to the east of landfall, along the western half of Galveston Island and the easternmost tip of Follets Island. In this area, the mean high water line (MHW) typically eroded 30-50 m (100-165 ft), whereas the vegetation line typically eroded 20-30 m (65-130 ft). Maximum erosion of the MHW line (up to 300 m) and the vegetation line (up to 100 m) occurred adjacent to San Luis Pass. A narrow band of washover sands, typically extending 20 m (60 ft) inland, was deposited along the non-developed portions of West Galveston Island. Because of the modification of the foredune system, these washover sediments typically extended 60-80 m (200-250 ft) inland along the developed portions of the shoreline. Erosion of the shoreline along the eastern part of Galveston Island was minor, although some washover channels formed where beach access roads cut through the dunes.

In contrast, the area west of landfall on Follett's Island experienced little shoreline erosion and virtually no washovers. This area was dominated by offshore directed winds during the passage of the hurricane, thus the main effect was the development of numerous storm surge ebb channels formed by the draining of West Bay. These channels are, on the average, 20 m (65 ft) wide, 55 m (180 ft) long, and up to 3 m (10 ft) deep; the largest of the channels is 40 m (130 ft) wide and 110 m (360 ft) long. These channels were initiated along low spots in the dunes (typically beach access roads) and grew landward by headward erosion until they encountered the highway, where they were partially deflected.

Much of the sand transported offshore during the storm returned to the beach within the following six months by progressive welding of swash bars to the foreshore to form a broad, flat berm. Since then, the patterns of shoreline accretion and erosion appear to reflect seasonal rather than long term changes. The vegetation line has yet to show any significant recovery 20 months after the storm and complete recovery of the beach to its pre-hurricane position seems unlikely.