2021 Volume 77 Issue 2 Pages I_703-I_708
Shallow fields with a depth of 4m or less are remarkable place of topographical changes, such as repeated movement of sand bars off shore by wave action on the sandy beach. It is also ecologically important places in rocky areas, where Ecklonia cava and Sargassum fulvellum grows, and a variety of fish and shellfish are inhabited. However, since the strong waves and complicated tidal currents, especially regarding the information of seafloor topography, its construction and maintenance had been behind in "places where difficult to measure" where neither ships nor people had access to them. Recently, a green laser sounder (Air Borne Bathymetry, ALB), which can be mounted on a small aircraft, has been developed and enabling safe and efficient measurement from shallow fields to land areas in coastal region. In this paper, the three-dimensional data up to the maximum water depth of 9-15m was acquired by measuring the coast of about 80km in the Sagami-Nada using ALB. This paper introduces the detailed seafloor topographic maps which are prepared from these results, report the example of seafloor topographic maps which published on Web for "Recreational Fishermen" who routinely fish on shore.
