Abstract
Causes of damages of seawall due to storm waves on the Hirono coast in Shizuoka Prefecture were investigated. In 1997 high waves were generated by five typhoons in this area. Direct cause of the failure of the seawall is due to the wave action, but gradual decrease of sea bed due to beach erosion is the indirect cause. Beach erosion of this area is deeply connected with the retreat of river mouth bar of the Abe River.
