BEACH EROSION MAPPING USING LIDAR AND A 3D LASER SCANNER: FOLLY BEACH, SOUTH CAROLINA

As of July 2005, a beach re-nourishment plan covering 5.34 miles (8.59 km) of shoreline has been implemented for Folly Beach, SC, approximately six miles south of Charleston, SC. The purpose of the re-nourishment project is to reduce storm damage to structures and infrastructure on Folly Beach, and to increase enjoyment of the beach for locals and tourists. According to the USCOE the amount of sand that will be placed on the beach during re-nourishment will depend on the beach profile at the beginning of the project. Based on present conditions, an estimated two million cubic yards of beach-quality sand will be placed seaward of existing dune lines.

To judge the effectiveness of current and future re-nourishment projects, LIDAR and 3D LASER scanner data was used to map sections of Folly Beach. The LIDAR data was flown as part of NOAA's Coastal Mapping Program and provided base information for the project with 15 cm vertical accuracy and sub-meter horizontal accuracy. Using hand-held GPS units, 3D LASER scanner locations were marked. The scanner was used to obtain 3D scans of beach profiles to sub-centimeter accuracy (horizontal) and millimeter accuracy (vertical). The scanner has a maximum field of view of 270 degrees horizontally and 360 degrees vertically. It can acquire both digital imagery and varying resolutions and fields of view for 3D scans. Using the data collected, the areas studied before re-nourishment can be reoccupied to obtain an accurate determination of the amount of sand deposited on the beach during re-nourishment. The maps created from the project will be used not only to assess the re-nourishment profiles, but as base-line information for future coastal process and erosion studies at Folly Beach. Scans of the area after major storms will be used to evaluate the amount of sand removed from the beach. The data will then be used in future beach erosion control plans and to help create a hurricane strength to erosion curve for the island.