Bathymetry survey using an aerial image for a very shallow water region

In recent years, many studies have been conducted on coastal erosion. In addition, the monitoring of bathymetry changes in shallow water regions is being acknowledged as an important aspect of studies on coastal erosion. Erosion monitoring implies monitoring of the bathymetry changes after the occurrence of major causes of erosion, such as typhoons. However, it could be very difficult to use the sensors typically employed to measure water depth, such as echo sounders, in very shallow water regions because of the relevant installation at the bottom of a surveying vessel. Therefore, water-level gauges or LiDAR can be used instead, although the former is difficult for bathymetry survey in a wide region and the latter is still very expensive to use in practice. Consequently, this study proposes an effective and economical bathymetry survey method based on aerial image data, and evaluates the proposed method by applying it to the bathymetry survey at a beach area.