Charting the Course: Shoreline mapping of Nantucket & Martha’s Vineyard with Topo-Bathymetric LiDAR
NOAA’s National Geodetic Survey (NGS) produces the national shoreline which provides critical baseline data for updating nautical charts; defining our nation?s territorial limits, including the Exclusive Economic Zone; and managing our coastal resources. This shoreline is applied to nautical charts and is considered authoritative when determining the official shoreline for the United States. Historically, the national shoreline has been produced using traditional stereographic compilation from tide-coordinated aerial imagery. In recent years, NGS has developed a state of the art based on airborne topobathymetric lidar data to derive consistent, highly-accurate shoreline contours (MHW, MLLW) that serve as the basis for updating the national shoreline. These shoreline contours combined with other navigational data are the foundation for NOAA?s nautical charts. NOAA identified a need to update the nautical charts for Nantucket and Martha?s Vineyard because several charts had not been updated since the mid 2000?s. In turn, NOAA tasked Dewberry and our partner Leading Edge Geomatics to acquire and process over 250 square miles of topobathy lidar and high resolution 4-band aerial imagery. After careful consideration of NGS? requirements and water conditions, we employed Leica?s Chiroptera II topobathy lidar system and Vexcel?s Ultracam to acquire the lidar and imagery data. The data that resulted from these surveys provided remarkable detail of the bathymetry of Nantucket and Martha?s Vineyard and proved to be a highly accurate and cost effective means of updating the shoreline contours and navigational data. This presentation will provide an overview of topographic/bathymetric lidar data, the photogrammetric mapping process, challenges encountered, along with the benefits of this approach.