Hydraulic Structures: Fourth Edition

WORKED EXAMPLES 665

Worked Example 15.2

At a depth of 20 m, waves of height 1.31 m and period 7 s are observed to
travel inshore. Estimate the run-up of the waves on the composite slope as
shown in Fig. 15.15.

Solution

At the place of observation, H1.31 m, d20 m and T7 s. From Fig.
14.4,L70 m, and from Fig. 14.3, c10.2 m s^1.

L 0 76.5 m.

For d/L 0 20/76.50.26, H/H 0 0.95 (Fig. 14.8) and so H 0 1.31/0.95
1.38 m.

WAVE BREAKING

0.38

1/3

(equation (14.41))

Hb2.0 m; db2.0/0.782.56 m.

RUN-UP

1. First trial.Assume a run-up of 2 m above SWL. The horizontal dis-
   tance from the wave breaking section to the run-up, s10.0
   5  6 5.626.6 m. The vertical distance is 2.02.564.56 m. The
   average slope is 4.56/26.60.17.

1.0160.17

0.5

(equation (15.21))

1.28

Ru1.281.381.8 m.

1.38



76.5

Ru



1.38

Ru



H 0

1.38



76.5

Hb



1.38

gT^2



2 π

Fig. 15.15 Sea wall of composite slope (Worked example 15.2)