Coasts

AS Geography

• The Coast is the narrow zone where the land overlaps the sea and interacts

• It is affected by Terrestrial, Human, marine and Atmospheric processes and their relationships.

• It is the most varied and rapidly changing of all landforms and ecosystems.

The Importance of Coastal Environments

• The Coastal zone is an interface between the sea and the land. Where the marine and terrestrial processes combine to produce a variety of changing landforms.

• Coasts suffer from rapid erosion and flooding thus can threaten lives and property.

• Changes to coastlines are both short term (e.g. Storms) and long term (Rising sea levels)

• Coastal ecosystems are coming under constant pressure from human activities e.g. (Sand dunes and coral reefs)

• Over half the world’s population live within 60km of the sea.

• Two thirds of our largest cities are within 60km of the sea.

• There is constant competition for it’s natural resources.

• Coastal management is becoming a major issue• Human intervention has lead to unexpected

impacts• With human development and global warming

demands will increase so need for management, particularly sustainable management strategies are needed.

DIFFERENT TYPES OF COASTAL ZONES:

Salt Marsh

Mudflats

Mangroves

Sand Dunes

Coral Reef

Diagrammatical Representation of factors effecting coasts

TERRESTRIAL:

TectonicsGeology

WeatheringDepositation

Biotic FeaturesE.g. mangrove

ATMOSPHERICGravity

Solar EnergyClimate

HUMAN:BuildingsPollutionTourism

DefencesConservation

Global Warming

MARINEWaves and Tsunamis

TidesSalt Spray

Biotic features (Coral)

COASTS

Waves• Created by the transfer of energy from the

wind blowing over the surface of the sea.

Tsunamis• Are created not by the wind but by submarine shock

waves generated by earthquakes or volcanic activity.

• With waves the greater the wind the greater the frictional drag and therefore the size of wave

• Those that travel short distances and are the result of local waves are seen as sea waves

• Those that are formed from distant storms and travel large distances are known as swell.

Wave Energy1. Wind velocity

2. Period of time the wind has blown

3. Length of the fetch

Exercise 1.• On a map of the UK find areas which have

the biggest fetch

Wave terminology

• CREST • HEIGHT• TROUGH• WAVE PERIOD• VELOCITY• STEEPNESS• ENERGY• SWELL

• CREST Highest point of the wave

• TROUGH lowest point of the wave

• WAVE PERIOD Time interval between the passage of

successive crests

• LENGTH (L) Distance between two successive waves• HEIGHT Distance between the trough and crest

• VELOCITY (C) speed of movement of a crest in a given period of

time

• STEEPNESS (H/L) ratio of wave height divided by length it

can not exceed 1:7 (0.14) as it will break

• ENERGY (E) expressed as E~ (Is proportional to)

LH2

• SWELL have low height, gentle steepness and

long wave length

Waves in Deep Water

Determined where the depth of water is greater than half the wave length

(D = > L) 4

Waves in Shallow Water

Depth is less than half the wavelength

D = < L) 2

• Plunge line is where the depth of water and the height are virtually equally and the wave breaks

• Body of foaming water that runs up the beach is known as the SWASH

• Body of water that runs back to the sea is the BACKWASH

The Coastal Zone

Wave Video

Constructive Waves

• These build beaches. Each wave is low. As the wave breaks it carries material up the beach in its swash. The beach material will then be deposited as the backwash soaks into the sand or slowly drains away.

• These waves are most common in summer

Destructive Waves

• These destroy beaches. The waves are usually very high and very frequent.

• The back wash has less time to soak into the sand. As waves continue to hit the beach there is more running water to transport the material out to sea. these waves are most common in winter

Exercise

• Complete activity 1 on page 82