Traditional techniques to evaluate coastal changes have often lacked the ability to capture the range of spatial heterogeneity in three dimensions. The development of LIDAR (Light Detection-and-Ranging) scanners has provided scientists with a more extensive, geomorphometric and time effective technique for studying coastal change. We examined the change in sediment and vegetation volumes on the east Matagorda Peninsula, Texas over a year’s time period using a terrestrial laser scanner during 5 sampling dates: September 2008 prior to Hurricane Ike landfall, September 2008 after landfall, December 2008 (winter sample), May 2009 (spring sample) and October 2009 (a year after landfall). We also analyzed aerial LIDAR data from Sept 2008 and Dec 2008 to estimate change in volume caused by the hurricane on the scanned plot. We hypothesized that: (1) the majority of volume loss would occur immediately after the hurricane, (2) most of the sediment volume loss would be returned to the site after a year, (3) calibrated terrestrial and airborne LIDAR would yield similar volume estimates and (4) embryonic and established dune systems would experience different volume changes. Both terrestrial and airborne point-clouds were registered to a common reference, spatially interpolated and volumetrically analyzed using Quick Terrain Modeler software.
Results/Conclusions
The terrestrial LIDAR results indicated that although erosion occurred immediately after Hurricane Ike, the system had recovered within a year. Landscape and sediment volume decreased the most immediately after Hurricane Ike, with recovery of volume in December, and subsequent smaller periods of fluctuation. Vegetation volumetric changes showed little loss immediately after Hurricane Ike, as compared to the loss in December. Results for the terrestrial and airborne LIDAR were sufficiently similar. Established dunes only lost vegetation in December, whereas embryonic dunes lost vegetation immediately after the storm and in December. In December, the increase in sediment volume is likely due to post-storm recovery as sand moved from the nearshore environment to the dunes, while the decrease in vegetation is likely a result of the natural growing season of annual coastal plants.
