Development of an imagery-based monitoring system for nearshore bathymetry by using wave breaking density

Abstract

An imagery-based monitoring system was developed for nearshore topography. The system was based on the wave breaking density observed using a land-based camera and calculated the bathymetry using a depth-controlled breaking wave model. The system was applied to the Fukude-Asaba Coast, Shizuoka Prefecture, where rapid topography change was expected around the outlet of pipeline-based sand bypassing. The validity of the system was verified through comparisons with bathymetry survey data. It is observed that the system can successfully capture the nearshore bathymetry change owing to a typhoon. It is also suggested that the accuracy is sensitive to the incident wave properties and therefore can be improved by introducing selective averaging in which only appropriate imageries were used for the depth estimation depending on the target depth zones.