Environmental Engineering Reference
In-Depth Information
4.3.5. Use of shoreward drift
4.3.6. Backpassing and beach re-shaping
4.3.7. Overfill
4.3.8. Shore profile renourishment
4.3.9. Part renourishments
4.3.10. Use of groynes
4.3.11. Use of nearshore structures
4.3.1 Direct Placement
Some beaches have been renourished by dumping truck-loads of sand on the
shore, as at Morib in Malaysia (Fig. 4.10 ).
Mention has been made (Sect. 4.2.7 , p. 49) of the beach at Bournemouth on
the south coast of England, which was renourished by pumping sand in from a
nearshore stockpile directly on to the depleted beach sector. A similar project was
carried out at Mentone, near Melbourne, Australia, on a coast that is much like
Bournemouth geologically. Receding cliffs in soft Tertiary sandstones were stabi-
lised by a sea wall and promenade built in 1937-1939, and the sandy beach that
had been supplied with sediment eroded from the cliffs then diminished. In 1977
the beach was renourished with about 160,000 m 3 of sand dredged from a rec-
tangular zone 1,800 m long and 600 m wide the sea floor (Fig. 4.11 ) and pumped
on to the shore (Fig. 4.12 ). The sediment supplied to the shore was bulldozed to
form a beach terrace, initially about 32 m wide, built 2 m above low spring tide
level. The sand was at first dark in colour because of a coating of silt, clay and
organic matter, but rain quickly washed this away. There was a problem because
the beach had been emplaced across several storm water outfall pipes, and the
first heavy rain saw gullies washed out across the beach by outflow. This was
remedied by extending the pipes seaward to the outer edge of the renourished
beach.
Fig. 4.10 Renourishment of
the beach at Morib, Malaysia,
by dumping sand from
lorries. © Geostudies
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