level changes or even from coastal or
and skeletons of small marine organisms.
underwater landsliding. Consequently,
The usual transport pathway is along the
rates of coastal erosion and accretion
coast by waves and currents (longshore
are very variable at regional, national and
transport, longshore drift). However,
international scales.
cross-shore (on/offshore) paths may also
All the above natural factors controlling
be strong and include windblown sand,
the coastal sediment budget are well
sand transferred due to wave swash on
included in the theoretical backbone
the beach or rip and tidal currents to
of the “littoral cell�. A littoral cell is a
offshore sand bars and sheets or even
coastal part that contains a complete
due to ice-push. Most sediment deposits
cycle of sedimentation including sources,
(e.g. deltas, sand bars, splits and dunes)
transport paths, and sinks. The cell
tend to migrate in a natural way over the
boundaries define the geographical area
year(s) according to the sediment budget
within which the budget of sediment
and
is balanced, providing the framework
important sediment banks ready to be
for the quantitative analysis of coastal
reworked and be engaged in the littoral
erosion and accretion. The sediment
cell. The sediment sinks are usually
sources are commonly river streams,
offshore losses at submarine canyons
sea cliff erosion, onshore migration of
and shoals or onshore dune migration,
sand banks, and material of biological
rollover, and deposition in bays and
origin such as shells, coral fragments,
estuaries.
weather
conditions.
Those
are
2.2. ANTHROPOGENIC EROSION Human activities along the coast (land
current technical capabilities. Factors
reclamation, port development, shrimp
such as the occurrence of storm events,
farming), within river catchments and
changes to the state of engineered
watersheds (river damming and diversion)
coastal defences, changing land use
and offshore (dredging, sand mining)
and sea level rise may alter the balance
in combination with the natural forces
between resistance of the coastline
included in a littoral cell often intensify
and the strength of the eroding forces,
coastal erosion locally and jeopardize
triggering coastal erosion even more
opportunities for coasts to satisfy their
severely.
socio-economic and ecological roles at a reasonable societal cost. Moreover, technical coastal defences are designed to protect areas of increased local economic interest, usually taking into consideration only the average prevailing environmental conditions and up to a limited static viability, restricted by the 11
