Monitoring Yearly Change Patterns of the Surface Tidal Trail (STT) in Tidal Flats: A Novel Morphological Indicator Extracted from a Near-Infrared Terrestrial Laser Scanner

Tidal flats play an important role in the geomorphological and biological dynamics of coasts. Research on the morphological evolution of tidal flats constitutes one of the key research issues pertaining to the sustainability of coastal ecosystems and related coastal defense issues. In this work, a novel indicator, the surface tidal trail (STT), was extracted from a near infrared terrestrial laser scanner and studied. The results show that the area intensity and size of STTs decline yearly. Meanwhile, the position shift of the peak value on the STT curves presents a similar pattern of hydrodynamic force in response to the seawall, which has been studied in previous works. Although no direct correlation between the STT intensity and the deposition rate was found, the corresponding hydrodynamic force data were not available in this work. The change process of STTs still provides a possible speculation that hydrodynamic force and the softness of tidal surfaces are two main factors that form and influence STTs. For future research, establishing the direct quantitative relationships among hydrodynamic force, topography, and STTs on different temporal and spatial scales would help to better understand this novel indicator.