Saltmarsh Expansion in Response to Morphodynamic Evolution: Field Observations in the Jiangsu Coast using UAV

Dai, W.Q.; Li, H.; Chen, X.D.; Xu, F.; Zhou Z.; and Zhang, C.K., 2020. Saltmarsh expansion in response to morphodynamic evolution: Field observations in the Jiangsu coast using UAV. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 433-437. Coconut Creek (Florida), ISSN 0749-0208. Most studies on the biological features and the morphodynamic indications of saltmarshes focused on individual plant groth, such as the stem height and the biomass. However, the understandings of the the planemetric patterns are limited. In this study, UAV (Unmanned Aerial Vehicle)-based observations are conducted in six saltmarsh areas along the Jiangsu coast, China. 3D point clouds, consequent DEM (digital elevation model) and colour orthomosaics are generated using the SfM (Structure from Motion) techniques. We track the variations in the locations of the saltmarsh front as well as the sizes and the distributions of patchs. The saltmarshes are distributed as a whole piece in the landside, while they turn to scattered patches to the sea. We find the locations of the saltmarsh front as a function of bed elevations and season. The area of a single patch is between 0 and 90 m². The number of the patches increases then decreases from landside to the seaside. For tidal flats in progradation, saltmarsh slowly expands seaward following the sediment accretion. This study highlights the abilities of the drone and the SfM technologies to measure the salt marsh distributions, and further to analyze the geometric characteristics and biomorphodynamics of tidal saltmarsh flats.