Abstract
On the Shimoni-ikawa coast facing Toyama Bay, offshore sand discharge into the deep sea through submarine canyons have occurred at several locations. The depth change in grain size of seabed material of this coast with these characteristics has not been investigated. In this study, ten survey lines were set to measure the depth distribution of grain size on the offshore seabed. Seabed sampling was carried out using divers in the depth zone between the shoreline and 20 m depth. The relationship between d50 and local slope determined from the bottom sounding was studied. It was found that d50 correlates well with the local slope independent of the water depth, and that the steeper the local slope, the greater the grain size of seabed material.
