Environmental Engineering Reference
In-Depth Information
Figure 13.4.
Wave runup ratios vs wave steepness and embankment slopes (Saville et al., 1962). Note:
R
runup height;
H
o
wave height;
L
o
wave length.
13.1.3.5
Wind setup
The wind setup (S) in metres is:
UF
62000D
2
(13.4)
S
in which U
design wind velocity over water in km per hour; F
wind fetch in km, nor-
mally equals 2Fe; D
average water depth along the central radial in metres.
The wind setup should be added to the wave runup. It will be noted that, apart from
long shallow reservoirs subject to high winds, the effect is very small.
13.2
SLOPE PROTECTION
13.2.1
Upstream slope protection
13.2.1.1
General requirements
The upstream slopes of earthfill on earth and rockfill dams need protection from erosion
by wave action on the reservoir. Earlier dams were often protected by hand placed rock,
but modern dams are generally protected by dumped rockfill, known as rip-rap.
