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GeoFactsheet
January 1997Number 8
Coastal Management
Since they are often extensive areas of flat, fertile, picturesque land, coastal areas are very attractive for a wide range of human activities.
However, approximately 25% of the English coastline has been heavily developed for housing, industry, agriculture and leisure and is
always under attack from both the local weather and the action of the sea, resulting in coastal erosion. This Factsheet will discuss the
problems caused by coastal erosion and the techniques used to reduce them.
Groynes
Breakwater (timber, rock or
other materials) at 90° to the
coastline to slow erosion and
sediment drifting by deflecting
strong currents, and to build up
beach level.
Polders
Timber or concrete enclosures to
encourage sedimentation, causing build up
of the coastline.
What is Coastal Erosion?
Coastal erosion can be defined as the loss of
land and the encroachment of the sea. It is a
complex process involving considerable
interactions between the following
components:
• Wind
• Wave action
• Tides
• Types of sediment and sediment
transport patterns
• Storms
Coastal erosion is a significant problem to land
use. It results in cliff face slumping, loss of coastal
land which may have been developed for human
activities, erosion of beaches and flooding. For
example, studies of the Kent coastline have
indicated retreat of cliff areas by 27m between
1872 and 1970. It is therefore essential to devise
coastal management plans to minimise any threat
to life and to protect natural and man-made
features.
Coastal Management
Coastal management plans have two fundamental
aims:
• To provide defence against water inundation
(flooding)
• To provide protection against coastal erosion.
The main component of these plans is the
presence of coastal defences. These can be
broadly divided into two categories:
Soft coastal defences
This is the use of natural systems in coastal
defence, for example, salt marshes and beaches,
which can absorb and adjust to wave and tide
energy. Soft coastal defence involves manipulating
and maintaining these systems, without changing
their fundamental structure.
Hard coastal defences - These are rigid
‘engineering’ solutions, made principally of
concrete. Examples include sea walls,
breakwaters, groynes and jetties (See Fig 1).
The principle objective of hard engineering is to
resist the energy of waves and tides by a fixed
structure. At present, such structures protect
approximately 10% of the British coastline.
The widespread use of hard coastal defences in
coastal protection has both advantages and
disadvantages (Table 1).
Fig 1. Examples of hard coastal defences
Stabilise cliff face.
Exam hint - Students should show
understanding that coastal erosion and the
resultant coastal land forms, such as
beaches and cliffs, are a result of the
interaction between all of these factors and
the shoreline.
Boulders
Reduce wave energy reaching
coastline and stabilise sediments.
Drainage
Concrete Wall
Absorb wave energy, preventing
erosion and flooding.
Iron Bar
High tide
Storm
