Coastal environments revision notes

Coastal environments
Coastlines are important to the human race. 50% of the world's population live on coastal plains
and in other locations with easy access to the sea. The coastline itself consists of a series of
different zones in which specific conditions prevail that depend on factors such as tides,…

Coastlines are dynamic environments that are undergoing continual change. In the short term,
tides, waves and longshore drift change the shape, form and appearance of elements of a
coastline. Changes in sea level bring about long term change.

The shape of the British Isles has altered continually over the
last…

The coastal system
Coasts are considered an example of an open system because inputs are received, and outputs are
transferred, across the boundary of the system.

INPUTS

Energy to drive the system. This is inputted in the form of waves, wind, currents and tides.
The input is irregularly boosted by…

Waves
Waves are a medium through which energy is transferred. They are created by the wind blowing
across the surface of the sea. Frictional drag increases as the wind speed increases, making the
wave bigger.

Wave energy depends upon three things:

1. The strength of the wind.

2. The length…

(height:length) and the wave `breaks' onto the beach. The rush of water up the beach is known as
swash and any water running back down the beach into the sea is the backwash.

Constructive waves
Constructive waves have a short amplitude and a long wavelength often up to 100m. They have a
low frequency of around 6-8 waves per minute. As they approach the beach, the wave front
steepens only slowly, giving a gentle spill onto the beach surface. Constructive waves produce a…

Effects of waves & Wave refraction
Most beaches are subject to alternating action of constructive and destructive waves. Constructive
waves build up the beach and result in a steeper beach profile. This encourages waves to become
more destructive ( as these waves are associated with steeper profiles).

With time though,…

Tides
Tides are the periodic rise and fall in the level of the sea.

Caused by the gravitational pull by the moon and sun. The moon has the greatest influence due to
its distance (pull is lower).

Oceans closest to the moon have an outward bulge. This causes high tide…

Storm surges
These are occasions when meteorological conditions giving rise to strong winds can produce much
higher water levels than those at high tide. One area affected by this phenomenon is the Bay of
Bengal.

Bangladesh has the worst record in the late twentieth century for storm surges.
Serious events…