Processing and accuracy of topobathymetric LiDAR data in land-water transition zones

Abstract

The transition zone between land and water is difficult to map with conventional geophysical systems due to shallow water depth and often harsh environmental conditions. The emerging technology of airborne topobathymetric Light Detection And Ranging (LiDAR) is capable of providing both topographic and bathymetric elevation information, resulting in a seamless coverage of the land-water transition zone. However, there is no standard and simple method for processing topobathymetric LiDAR data into a Digital Elevation Model (DEM). In this study, a method is developed for the creation of a DEM based on high-resolution topobathymetric LiDAR data from the Knudedyb tidal inlet system in the Danish Wadden Sea. The vertical accuracy of the LiDAR data is determined to ±8 cm at a 95 % confidence level, and the horizontal accuracy is determined as the mean error to ±10 cm. The LiDAR technique is found capable of detecting features with a size of less than 1 m. The created DEM seamlessly covers the land-water transition zone extending down to approximately 3 m water depth which is the maximum penetration depth of the LiDAR system at the given challenging environmental conditions in the Wadden Sea.