COMPARISON OF AERIAL PHOTOGRAPHIC WET DRY LINE EXTRACTIONWITH PROJECTION OF WATER LEVELS ONTO LIDAR DATA

摘要

For over a century scientists have attempted to define what indicates the position of theland water interface, or shoreline. The determination of the shoreline position is criticalin calculating shoreline erosion or accretion rates. Studies show that long term data setsare essential when attempting to accurately measure shoreline evolution. LIDAR is oneof the latest technologies to be used in coastal studies. Large amounts of LIDAR datacan be collected in short amounts of time, and errors associated with LIDAR are usuallyless than 30 centimeters. In order to use LIDAR as a method for measuring shorelineevolution, it must be compared to past methods.This paper demonstrates how LIDAR data can be used to estimate shoreline positionscompatible with historical data. Seven study locations on the North and South Carolinacoast were examined. LIDAR and digital orthophotographs were collectedsimultaneously. The LIDAR data for each location was gridded at 0.5 meters, andorthophotographs were produced with 20 cm pixels. Digitization of the wet dry line fromthe digital orthophotographs was compared to water elevations projected onto LIDARdata. Results show that the projection of water levels onto LIDAR data is well within theerrors associated with digitization of the wet dry line. The use of LIDAR data to estimatethe wet dry line is feasible, and LIDAR data improves the quality of long term data setsdue to the relatively low errors and fully quantifiable distortions.