| Since the completion of a 398,000 m3 nourishment project along 2 km of Rehoboth Beach, Delaware in August 2005, the subaerial volume and area of the northern 25% of the beach has been monitored monthly through the use of terrestrial light detection and ranging (LIDAR) surveys. Traditionally, Delaware Department of Natural Resources and Environmental Control and the U.S. Army Corps of Engineers use analyses of beach width from aerial imagery and volumes estimated from widely spaced profile surveys to assess nourishment performance and assist in determining renourishment quantities. However, these survey methods lack the spatial and temporal resolution often needed for management strategies. This thesis investigates a method of monitoring beach nourishment performance using terrestrial LIDAR, which allows for high-temporal and spatial resolution models of subaerial beach topography on a monthly basis. The results of this study are presented in two sections. The first section describes a method of developing digital elevation models (DEM) from terrestrial LIDAR surveys of a 500 m × 70 m stretch of Rehoboth Beach over a 16-month period (January 2006 through April 2007). The second section is a series of appendices presenting maps and an outline of data collection/processing techniques. Analyses of the digital elevation models created from our frequent surveys: (1) allow for a better understanding of the range in variation in beach area and volume, especially that due to storm events, (2) provide more accurate volume estimates than traditional profile surveys by as much as 8%, and (3) indicate that the area and volume do not covary, limiting the usefulness of using aerial imagery in estimating volume. |
