Environmental Engineering Reference
In-Depth Information
that there was a need for the public to be better informed on how renourished
beaches may perform, and a need to support accurate and sustained monitoring.
A U.S. Army Corps of Engineers (
1994
) report examined more than 100 replen-
ished beaches and concluded that actual costs and volumes of sand placed were
within 5 % of predicted values (Houston
1995
; Sudar et al.
1995
), but Pilkey
(
1995
) cited some omitted problems, including the fact that some beaches were
severely depleted between renourishments. At Tybee Beach, Georgia, where the
costs and volumes of beach renourishment in 1976 and 1987 were indeed less than
predicted, the first placement disappeared within a year, so that for a decade Tybee
was without any beach. Damage done to backshore property and structures should
really be included as a cost item. Predictions remained uncertain: the 1993 renour-
ishment of Folly Beach, South Carolina, was expected to require repetition every
8 years, but this was already necessary after 1 year (Pilkey
1995
).
One response to the need to retain renourished sediment on the shore is seen at
Porthcawl in South Wales, where tarmac has been introduced to stabilise a shingle
beach (Fig.
4.30
).
It is now generally acknowledged that renourished beaches will be eroded, and
will have to be replaced at intervals, and that this will require substantial and on-
going expenditure by governments and coastal communities. The alternatives are
to use solid protective structures, which do not co-exist well with beaches, or to
allow natural changes to proceed on the coastline, abandoning eroding land (the
process termed managed retreat). It seems likely that demands for beach renour-
ishment will continue as a component of comprehensive coastal management
programmes, because of increasing coastal population and development stimulat-
ing further demands for beach recreation, because of greater public awareness of
beach erosion problems and because of widespread opposition to the use of hard
structures in coastal protection. Objections to nearshore dredging and truck traf-
fic as means of obtaining and transporting sediment for beach renourishment were
voiced in Adelaide, South Australia (Sect.
4.3.4
, p. 67), but are likely to fade as
Fig. 4.30
The shingle beach
at Porthcawl, South Wales,
stabilised in tarmac.
© Geostudies
