2021 Volume 77 Issue 2 Pages I_805-I_810
InAkiya (Okuzure-Hamada) area of the Yokosuka coast, beach nourishment using 8×104 m3 of gravel was carried out between 2007 and 2014 to recover a sandy beach.After gravel nourishment, a steep slope was formed, causing wave overtopping and gravel transport behind the seawall during typhoon waves because of the small relative height betweeen the crown of the seawall and the elevation of the beach. Part of gravel was transported into a sandy beach inside the fishing port south of the gravel beach. Beach changes after the gravel nourishment were investigated using the monitoring data to make out a method preventing gravel transport to the fishing port and wave over-topping. As a result, raising the crown height up to the berm height of 3 m near the basement of the L-shape groin was effective and the maintenance of pushing gravel deposited over 3 m toward the shoreline was required.
