Geoscience Reference
In-Depth Information
Relevant reading
Coyne, M.A. & Sterrett, E.H. (2002)
California Beach Restoration Study
. California Department of Boating and
Waterways and State Coastal Conservancy, Sacramento, CA. (Available at: http://dbw.ca.gov/beachreport.htm)
Griggs, G.B. & Savoy, L. (1985)
Living with the California Coast
. Duke University Press, Durham, NC.
Flick, R.E. (1993) The myth and reality of southern California beaches.
Shore and Beach
61
, 3 -13.
Liedersdorf, C.B., Hollar, R.C. & Woodell, G. (1994) Human intervention with the beaches of Santa Monica
Bay, California.
Shore and Beach
62
, 29 -38.
Sherman, D.J., Barron, K.M. & Ellis, J.T. (2002) Retention of beach sands by dams and debris basins in
southern California.
Journal of Coastal Research
(Special Issue)
36
, 662-74.
Willis, C.M. & Griggs, G.B. (2003) Reductions in fluvial sediment discharge by coastal dams in California and
implications for beach sustainability.
Journal of Geology
111
, 167- 82.
Brunsden & Moore (1999) noted large-scale
gravel removal from Chesil Beach. In areas of
finite sediment volume, this may produce a seri-
ous erosion problem. Large scale, commercial
beach and sand dune mining is also practised.
In Australia and South Africa, natural concen-
trations of heavy minerals in dune sands are
exploited. Offshore aggregate removal is a com-
mercial operation that has led to a reduction
in the nearshore sediment supply and also to
changes in bathymetry (see Chapter 10). These
in turn alter wave refraction patterns and may
cause readjustments in shoreline morphology.
The English village of Hallsands was eroded
as a result of offshore aggregate extraction for
harbour construction (Pearce 1996). Nearshore
sediment extraction also takes place in the search
for precious minerals (e.g. diamonds off the
South African and Namibian coasts).
'Cleaning' beaches of litter including seaweed
on drift lines can cause loss of potential dune
nucleation sites and nutrients needed to pro-
mote plant growth.
8.6
MANAGEMENT AND REMEDIATION
8.6.1 Management approaches
Management of sedimentary coastlines involves
consideration of (i) utilization of the coast such
as to minimize human impact on the sedimentary
system, and (ii) balancing human utilization with
a naturally dynamic system. Management of sedi-
mentary coastlines must therefore begin with an
understanding of the processes that shape and
maintain those coasts at time-scales relevant to
management. The discussion above should imme-
diately make clear that this is a difficult task. The
range of processes and the physical constraints
that operate at varying spatial and temporal
scales are unlikely to be well understood at any
coastal location, and hence a wide margin of
error is inherent in sedimentological assessments
related to coastal management. Existing con-
straints on a coastline imposed by human inter-
ventions (Fig. 8.17a), and the potential impact
of further intervention on adjacent stretches of
coastline, impose additional considerations for
management of sedimentary coasts.
Applied sedimentological investigations in
the coastal zone are therefore typically under-
taken for two purposes. One is the design and
8.5.4 Recreational activity (human trampling,
leisure vehicle activity)
The coastal zone has traditionally attracted
human visitors who have utilized it as a food
source, living area and more recently as a leisure
area. Recreational activities can be a major fac-
tor in coastal sedimentology. In coastal dunes,
human trampling and use of recreational vehicles
can result in large-scale reactivation of fixed
sediment (Gilbertson 1981). Car parking on
beaches can induce compaction of the sediment
and interfere with natural sediment transport
in the intertidal and adjacent supratidal zones.
