Environmental Engineering Reference
In-Depth Information
Fig. 4.11
The coast at
Mentone, Port Phillip Bay,
Australia, showing the area
from which sea floor sand
was dredged (
A
) and the zone
where it was dumped (
B
) to
be pumped on to the shore
(see Fig.
4.12
). © Geostudies
Fig. 4.12
Sand pumped on
to the shore at Mentone, Port
Phillip Bay, Australia, and
deposited as a renourished
beach. © Geostudies
There are limits to the distance over which pumping of sand is effective. On
the Belgian coast 500,000 m
3
of sand dredged from the fishing port at Ostend was
pumped on to the shore between Bredene and Klemskerke in 1978 to renourish
a depleted beach up to a kilometre to the west, but beyond this it was necessary to
pump from another source, coarse shelly sand from the offshore shoals at Stroombank
and Kwintebank. Some 8.5 million m
3
of sand delivered from these sources permitted
beach placement on 8 km of coast near Zeebrugge (Kerckaert et al.
1986
).
More recently at Ostend, beach renourishment has been undertaken in 2013
using sediment dredged from offshore sand banks. A mix of water and sediment
was pumped aerially directly from the dredging vessel onto the beach or nearshore
zone. This process also known as 'rainbowing' due to the shape of the slurry as it
passes through the air (Fig.
4.13
) is widely used where sediment has been dredged
from the sea floor or from estuaries and inlets along the coast.
As a sequel to the Bournemouth project, several other seaside resorts on the
south coast of England have had their beaches renourished in front of esplanades.
Some have used boulder armouring to reinforce the sea wall, and covered this with
imported shingle to form a new beach.
