海岸堤防の越波防止効果に関する二,三の問題

Abstract

In this paper, results of the model tests on wave overtopping for the seawalls at Port Island inKobe Harbor, Sakai Harbor in Osaka Prefecture, Yui Coast in Shizuoka Prefecture, Sennan Coastand Nishikinohama Coast facing Osaka Bay are presented. Based on the above results, the effect ofseawalls and seadikes on prevention of wave overtopping is discussed.The main results are summarized as follows:(1) When incident waves do not break in front of the seawall as the water depth at the tocof the seawall is large compared with the incident wave height, wave absorber works in front of theseawall are not so effective to prevent wave overtopping or, on the contrary, increase rather thequantity of wave overtopping in a certain case. Consequently, the scale of wave absorber worksshould be decided carefully in such a case.(2) When the waves break just in front of the seawall as the water depth is not large com-pared with the wave height, shallowing the water depth at the toe of the seawall to decrease thequantity of wave overtopping is inure effective than increasing the wall height from the still waterlevel. Therefore, artificial beach nourishment is available from view point of not only enlargementof the beach but also disaster prevention.