DETECTING MORPHOLOGICAL CHANGE ON GALVESTON ISLAND WITH AIRBORNE AND TERRESTRIAL LIDAR

With frequent hurricanes and storm surges in the Gulf of Mexico and their significant effects on the barrier islands’ geomorphology in general and particularly erosion, there is an increasing demand for an effective and accurate monitoring systems to quantify changes in morphology. Advanced geodetic technologies such as LiDAR and Terrestrial Laser Scanners (TLS) have emerged as tools to perform this type of monitoring. They provide fast, accurate and reliable results when tied into accurate ground control, e.g. through GPS or survey benchmarks. A series of LiDAR airborne campaigns have been examined on Galveston Island in order to identify morphological changes and erosion hotspots for further detailed investigation with TLS.

In order to monitor coastal erosion rates, sequential airborne and terrestrial LiDAR scanning are employed for both large scale and small scale monitoring. Airborne LiDAR campaigns are available for the entire test site of Galveston Island for the years 2001, 2006, and 2010. Comparing these elevation data sets allows for the identification of erosion/accumulation over these time periods. All three airborne LiDAR campaigns were cross-validated in order to obtain accuracy information. Terrestrial LiDAR serves two purposes, i) it provides calibration data (both for horizontal and vertical referencing) for airborne data, and ii) it provides more detailed information about erosion hotspots. The results of two airborne LiDAR campaigns of the years 2001 and 2006 show elevation changes between -15 to +6 meters which mainly relate to hurricanes and storm surges during that time period. Beyond these preliminary results, validated elevation change including uncertainty information will be presented for all three airborne LiDAR data sets and the acquired terrestrial laser scans.