Terrestrial laserscanning of tidal flats-a case study in Jiangsu Province, China

Terrestrial laserscanning (TLS), also called ground-based LiDAR (Light Detection And Ranging) is a relatively new method which revolutionised geomorphological research in many domains. However, detailed studies of tidal flats by TLS have not been described in the literature yet. This study aims to fill this methodological gap by the application of TLS at two different locations on the coast of Jiangsu Province, Eastern China, and an assessment of the usability of this method for geomorphological research in such environments. The acquired point clouds are first processed to remove erroneous and noisy points. Subsequently, point clouds are computed to produce polygonal meshes and grid-based digital terrain model (DTM) more commonly used by the scientific community. The accuracy of the measurements is assessed by an analysis of elevation deviations for flat and horizontal concrete blocks. High quality point clouds with point densities of up to 4,000 points/m(2) were acquired for a distance of up to 200 m. The data allowed for the detection of small landforms such as tidal channels, creeks and ripples in centimetre and decimetre scale. The point clouds had an average error of approximately 3 mm, however for some few points errors of up to 1.8 cm were detected. Based on the results it can be concluded that TLS can be a useful additional method for geomorphological research on tidal flats due to its ability to describe the landforms from high density point clouds. Repeated scanning could therefore provide data to quantitatively and qualitatively describe geomorphological changes over wider areas and thereby improve the understanding of sedimentation and erosion on tidal flats.