Coastal management

Question 1

Seawall functions (2)

Answer 1

• Protect Cliffs from erosion by deflecting waves

- Barrier to prevent flooding

Question 2

Drawback of seawall

Answer 2

seawall deflects wave energy, results in powerful
backwash of breaking waves which increases the rate of erosion at
the base of the seawall–> can undercut and may collapse if not
reinforced in time

Question 3

Breakwater function (2)

Answer 3

reduce the intensity of wave action in inshore waters –> reduce
coastal erosion by breaking incoming waves out at sea

change the direction of waves and reduce longshore drift

Question 4

Function of Groyne (3)

Answer 4

Prevent removal of sediment (by trapping it) on the side facing the longshore
drift

sediments trapped can build a sandy beach, which provides distance between sea cliff (water only rewash cliff during high tide)

● Can slow down waves & reduce their energy –> provides protection from
flooding and erosion

Question 5

Revetment Function (2)

Answer 5

Allow some water to pass through, offering partial resistance

acts as a barrier against waves by absorbing the energy of the waves
and prevent the cliffs from being eroded

Question 6

Rock Armour function (2)

Answer 6

Massive blocks of natural rock placed in position and piled up at the
base of a cliff for added strength and protection against wave action
(not bounded)

Question 7

Gabions function (1)

Answer 7

reduce the impact of waves on the cliff and prevent the cliff from being
undercut

(bundled in a mesh and constructed at base of cliff)

Question 8

Tetrapods function (3)

Answer 8

● Moulded multi-angular concrete shapes
● Arranged in lines or heaps along coastline / at base of cliffs
● create an interlocking, porous barrier that dissipates the power of
waves and currents.

Question 9

Beach nourishment (3)

Answer 9

● Sand and shingle are added to a beach to make it wider.
● To increase the distance a wave has to travel to reach the cliffs
● Wave will lose more energy and have less erosive power when it
reaches the cliffs.

Question 10

Grow vegetation function (1)

Answer 10

● Sand dunes formed by prevailing winds are often colonized by vegetation (or can also manually plant vegetation),
which stabilises the dunes and prevents the sand from being blown away.
(Dune erosion occurs when the vegetation are damaged or destroyed)

Question 11

Managed realignment (3
)

Answer 11

● Breaching an existing coastal defence, such as a sea wall or an
embankment, and allowing the land behind to be eroded / flooded by the
incoming tide.
● This land is then left to be colonised by saltmarsh vegetation  can break
up the waves and reduce their speed, reducing the erosive power of
waves.
● The marshlands also limit the area which waves can reach inland hence
preventing flooding.

Question 12

Retain existing vegetation (2)

Answer 12

● Mangroves served as a natural buffer zone between the sea waves and
coastline. They form the vital link between the sea and land.
● When this link is removed, the coastline is vulnerable to processes of
erosion.
( ● Expensive bund walls and seawalls are required to protect the coastlines
from erosion when mangroves are removed.
● Managing mangroves is a more economical and environmentally-friendly
method.)