Master of Science (MS)
Oceanography and Coastal Sciences
This study focuses on hurricane-induced changes in land and vegetation primarily in two study areas, the Breton Sound Estuary and the Chandeleur Islands, southeast of New Orleans, Louisiana. Breton Sound Estuary consists of the Caernarvon Diversion, a fresh water diversion of the Mississippi River that supplies this region with managed pulses of fresh water and sediments. The Chandeleur Islands are a chain of barrier islands that are uninhabited and transgressive in nature. A sequence of hurricanes in the past two decades has greatly altered both areas significantly. Satellite data were analyzed for a period of 24 years (1987-2011) of Breton Sound Estuary region and for 14 years (1997-2010) of the Chandeleur Islands. Landsat 5 Thematic Mapper data were used to classify and analyze changes using ERDAS IMAGINE 9.3 software. Images were classified into land and water classes using a hybrid classification technique that is unlike the techniques used in the past. Quantitative spatial analyses of the extent of land loss, vegetation changes and beach loss/gain over time were performed. Three change detection techniques were used in this research, which include post-classification spatial intersection, Change Vector Analysis (CVA) and image differencing. Maximum land loss in the Breton Sound Estuary region was due to Hurricane Katrina in 2005 when 196 km2 of land was converted to water from November 2004 to October 2005. Marsh area loss in the 24-year time series coincided with the overall land area loss. An increase in marsh area was detected in three segments of the time series i.e. 1987 to 1991, 1992 (after Hurricane Andrew) to 2003 (before Hurricane Ivan) and 2006 (after Hurricane Katrina) to 2010 indicating some recovery between hurricane years. At the Chandeleur Islands, most of the land loss over the past decade was due to four major hurricanes since 1997; Hurricane Georges in 1998, Hurricane Ivan in 2004, Hurricane Katrina in 2005 and Hurricane Gustav in 2008. The most significant hurricane that impacted these islands was Hurricane Georges in 1998 that resulted in a land loss of 76.5% measured from 1997. The land area increase after the impact of Hurricane Gustav in 2008 to 2011 was very low ranging from 0 km2 to 2 km2. Shoreline change detection results indicated that the barrier islands moved westward (landward), a maximum of 1.7 km in the southern section. Seven kilometres of the linear coastline was lost in the northern tip and 15 km in the southern tip. The change detection analysis and the shoreline change analysis indicated that the southern section of these islands has undergone greater damage due to erosion than the northern section.
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Raghunathan, Vandana Varshini, "Hurricane Induced Land and Vegetation Changes in the Breton Sound Estuary and Chandeleur Islands Using Landsat 5 TM" (2011). LSU Master's Theses. 152.