IMPACT OF HURRICANE ANDREW ON THE TIMBALIER ISLANDS TERREBONNE PARISH, LOUISIANA Shea Penland 1 , Chris Zganjar 2 , Karen A. Westphal 2 , Paul Connor 1 Jeff List 3 and S. Jeffress Williams 3 INTRODUCTION The U.S. Geological Survey (USGS), in cooperation with the Coastal Research Laboratory in the Department of Geology and Geophysics at the University of New Orleans (UNO) and the Center for Coastal Energy and Environmental Resources at Louisiana State University (LSU), is investigating the processes of coastal erosion and wetland loss in Louisiana (Sallenger and others, 1987; Sallenger and Williams 1989; Penland and others, 1992). Building on the USGS Louisiana Barrier Island Study (Williams and others, 1992), this USGS Open-File Report depicts the Hurricane Andrew damages to the Timbalier Islands in Terrebonne Parish and Lafourche Parish, Louisiana. The objective is to compare and contrast the impact of Hurricane Andrew with previously published data on the long-term (1887-1988) and short-term (1978-1988) erosion of the Timbalier Islands (McBride and others, 1992). The Timbalier Islands are located about 120 km south-southwest of New Orleans (Figure 1). This barrier island shoreline is 30 km long and extends east from Cat Island Pass to Raccoon Pass. The Timbalier Islands represent a flanking barrier island system developed from the reworking and erosion of an abandoned distributary of the Lafourche delta complex within the Mississippi River delta plain (Penland and others, 1988). The Timbalier Islands consist of Timbalier Island to the west and East Timbalier Island to the east. Timbalier Shoal, located between the two islands within Little Pass Timbalier, is a transient area of moving sand, sometimes subaerial, and is not included in the discussion or area statistics. In this Hurricane Andrew impact assessment, the authors used the methods and transects from McBride and others (1992) to insure data compatibility of the new measurements and analysis (Plate 7). HURRICANE ANDREW Hurricane Andrew developed from an easterly wave which moved off the west coast of Africa into the Atlantic Ocean on August 14, 1992 (Rappaport, 1994). It developed into a tropical storm on August 17, 1992 approximately 1500 miles east of the Lesser Antilles and moved west-northwest for four days with little change in intensity. It gradually strengthened to be classed a Saffir/Simpson Category One hurricane (minimal strength) on August 22, becoming a Category Five hurricane by the afternoon of August 23 with 1 Department of Geology and Geophysics, University of New Orleans 2 Center for Coastal, Energy and Environmental Resources, Louisiana State University 3 U.S. Geological Survey, Coastal and Marine Geology Program 1