Monitoring bed level dynamics in mangrove wetlands by Laster ranging technique

Climate change-related temperature increases and sea-level rises have a significant impact on coastal environment. The morphodynamic processes on tidal flats under this global change have been studied by many numerical and analytical models. Studies on morphodynamic processes requires accurate bed-level measurement data to reflect the complex intertidal morphodynamics. The newly-developed SED sensor (Surface Elevation Dynamics sensor) has been introduced to provide continuous long-term monitoring with relatively low cost of labor and acquisition. However, when in use, the instrument is inserted directly to the ground, inducing scour pits around measuring point. Thus, we introduce a new instrument which make use of laser ranging called LSED (Laster based Surface Elevation Dynamics) sensor. It could avoid touching the bed surface and obtain data with 1-millimeter vertical resolution. The developed sensors can be installed at both bare and vegetated tidal flats to monitoring short-term bed level changes under different settings. In light of this, we set up a group of Laser-SED sensors in National Mangroves Park in Hailing island, Yangjiang. Firstly, these new instruments were tested using data obtained from LSED sensors and traditional Sediment Erosion Bars. An excellent agreement in these measurement methods indicating that LSED sensors are reliable in bed-level measurements. The obtained LSED-sensor data was subsequently used to develop machine learning predictors, which revealed the main drivers of the accumulative and daily bed-level changes. We conclude that the LSED-sensors can further support machine learning applications to extract new knowledge on coastal biogeomorphic processes.