View stunning SlideShares in full-screen with the new iOS app!Introducing SlideShare for AndroidExplore all your favorite topics in the SlideShare appGet the SlideShare app to Save for Later — even offline
View stunning SlideShares in full-screen with the new Android app!View stunning SlideShares in full-screen with the new iOS app!
Mind-map all the different things people use coast
Some coastlines are under threat of erosion
causing cliffs to retreat and beach material to be
lost. Others are at risk from coastal flooding.
In many cases the decision has been made to
try and reduce the erosion to protect the
coastline. This is called COASTAL
Coastal Management = The attempt by
people to maintain the natural features of
the coast for their own advantage
Soft engineering options
are often less expensive
than hard engineering
options. They are usually
also more long-term
and sustainable, with
less impact on the
options tend to be
expensive and shortterm options. They
may also have a high
impact on the
GROYNES – Wooden/concrete barriers built at
right angles to the beach.
One of the most frequently
used protection types used to
stabilize the coast.
They are help build up beach
material by preventing
Groynes build up beaches at a
small scale & are cheaper than
Groynes can reduce the amount
of sediment downcoast, which
may have an effect on areas
elsewhere (as these areas might
get starved of material and their
beaches get smaller).
They also have a short lifespan.
Vertical or sloping structures, built along the
shoreline in an attempt to stop erosion
Can be constructed from any type of materiale.g. from sand-filled bags to reinforced
Often controversial as they are ugly and can
be destroyed eventually.
Waves scour at the bases of the walls &
eventually undermine them, causing failure.
As a result, seawalls only provide temporary
protection before needing replacement.
They are expensive.
The object of defence work is to dissipate
wave energy (beaches do this very well)
whereas sea walls have the opposite effectwalls concentrate wave energy and reflects
it back at the sea.
The wall receives maximum impact which
weakens the structure.
Often situated away from the cliffs and attempt to reduce the energy of the
waves before they reach the cliffs/ coastline
Designed to allow
sediment to pass
through them, which
longshore drift is
absorb the energy
of the waves before
they reach the cliffs.
prevents wave scour.
They are also very
cheap, but they do
need to be replaced
quite often & can be
regarded as ugly.
Large boulders that work in a
similar way to seawalls, but they are
They are able to dissipate wave
energy by absorbing the impact of
Rip-rap structures do not suffer from
the wave scour that afflict the
Clearly, masses of boulders are much
cheaper than sea walls & are
However, they are pretty unappealing
to the eye & can reduce the
recreational value of the beach.
They can also act as groynes & can
prevent downdrift movement of
The principle of gabions is
similar to the Rip-rap method
of protection (i.e. dissipation of
wave energy etc).
However, gabions use smaller
rocks and are encased in a
wire mesh; this means that
local beach material could be
used, which enables the
structures to blend in more
with its surroundings.
Potential problems arise when
the wire mesh breaks (risk of
injury) and one could also
argue that they are pretty
Gabions may not last for a
long period of time (5-10
Replacement of sand/pebbles on
The best example is the
nourishment of beaches at Miami
Beach where 17.7 million m³ of
sediment was dredged & moved to
the beach to provide an area for
recreation & also to protect the
expensive properties that were
found in the location.
nourishment is that one severe
storm event may remove vast
•Sand dunes and cliffs are a
natural sea defence.
•They dissipate wave
energy and protect the area
behind from flooding.
•They are stabilised by
fences or by planting
grasses to hold the sand
and rocks together.
•This is cheap and
effective but easily
damaged by people if not
MANAGED RETREAT/ COASTAL REALIGNMENT
•This is where in certain areas, the
sea is allowed to reclaim (flood)
the land that was once covered
by the sea.
•This often means that farmland
is lost, but the pressure of floods
are reduced because it creates
salt marshes that can be flooded
and can absorb the energy.
•A natural and long-term
•Does require compensation for
land that is lost.
MANAGED RETREAT/ COASTAL REALIGNMENT
Cheaper in the long term as
structures not having to be
Sea levels rising- can’t expect to
keep position of the current
Will produce wetland, which
would have huge
Salt marshes absorb tidal/wave
energy and reduce the impact of
Only giving back what naturally
belongs to the sea
Farmland and livelihoods lost
Coastal realignment, but for how
long? Where do you draw the
boundary? Can you keep
Cost of compensation will be
Can’t be adopted in built-up
Some farmers unwilling to sell
Do nothing –
How does it work?