Relations between slopes and beach topography on swash zones of the Sarukotu coast

Abstract

ABSTRACT：This paper describes on relations between slopes and beach topography on swash zones of the Sarukotsu coast before (1975) and after (1986) constructing training jetties at the river mouth of the Sarukotsu River of Hokkaido, Japan. The relation between the ratio tanα/tanβ ) of the slop tanα of the land side and the slop tanβ of the sea side from a criterion of the shoreline and ratio (hc/Xc) of the water depth hc on the bar top and the horizontal distance Xc from a criterion of the shoreline to the position at the bar top was clarified by the sounding in 1975 and 1986. Consequently, it is clear that the relation between (hc/ Xc ) and (tanα/tanβ) is given by hc/Xc A ・ (tanα/tanβ)+B, where A and B is a constant. In addition, it can be explained by the ratio tanα and tanβ that is the maximum of the wave run up that the wave reflection coefficient is large at tanβ of the steep slope and is small at tanβ of the gentle slope.