Abstract
Beach changes after the gravel nourishment on the Katayamazu coast were investigated by field observations, a field experiment and an analysis of monitoring survey data. It was found that the nourishment gravel was mainly deposited in an area shallower than -5 m, and the length of beach where the planned beach width was satisfied reached 61% by 2017. It was confirmed that the gravel nourishment was effective for the shore protection. However, the volume deposited in a zone shallower than -5 m was less than that of the total amount of the gravel nourishment. Three factors were considered for this reason: (1) decrease in volume owing to the mixing of two kinds of nourishment materials, (2) movement of gravel behind a seawall by wave overtopping, and (3) movement of sand from a place shallower than -5 m to an offshore area during storm waves.
