7COASTAL STUDIES

COASTAL PROCESSES

FACTORS influencing the RATE

OF EROSION

TYPES OF WAVES

TYPES OF WAVES

CONSTRUCTIVE

WAVES

DESTRUCTIVE WAVES

CONSTRUCTIVE WAVES

CHARACTERISTICS

Low energy and are common along gently

sloping coasts

The swash STRONGER than the backwash

(swash > backwash)

The constructive waves are called

spilling breakers

Spilling breakers are produced by waves

of long wavelength and low height

DESTRUCTIVE WAVES

High energy waves that erode the coast.

They are common along steep sloping coasts.

These waves are called plunging breakers

where it tend to carry material off the beach

and into the sea (BACKWASH > SWASH)

Plunging breakers are produced by waves of

short wavelength and high height

CHARACTERISTICS

Coastal processes

EROSION

TRANSPORTATIONDEPOSITION

COASTAL EROSIONAL PROCESSES

CORRASION (or

ABRASION)ATTRITION

SOLUTION (or CORROSION)

HYDRAULIC ACTION

C A S H

CORRASION (or ABRASION)

When materials carried

by waves are thrown

repeatedly against a coast,

they gradually erode the

coast

ATTRITION

When materials are

carried in waves, they

collide with one another

Eventually, the

materials break down into

smaller pieces and

become smoother and

more rounded over time

SOLUTION (or CORROSION)

Water in the waves reacts

chemically with the soluble

minerals in the rocks along the

coast and dissolves them

Over time, the coast becomes weakened and

is eroded.

HYDRAULIC ACTION

The force of moving 

water currents rushing into

a crack in the rock face or

cliff face

FACTORS influencing THE

RATE OF EROSION

TYPE OF WAVE

NATURE OF

COASTAL ROCKS

THE GRADIENT

OF THE COAST

IMPACT OF

HUMAN

ACTIVITIES

TYPE OF WAVE

Destructive waves cause

MORE EROSION that

constructive waves – have a

more powerful backwash than

swash

NATURE OF COASTAL ROCKS

Rocks that make up the coast may have different resistance to erosion

In terms of mineral composition: Coasts that are made up

of granite, basalt, and

dolomite – MORE

RESISTANT TO EROSION

than,

Coasts that are made up

of limestone, shale, and

clay

In terms of lines of weakness:

Coastal rocks that have

more lines of weakness will

be MORE EASILY ERODED

than,

Those with fewer lines of

weakness

THE GRADIENT OF THE COAST

Coasts with a STEEPER GRADIENT

tend to COLLAPSE FASTER

IMPACT OF HUMAN

ACTIVITIES

Human through their activities can speed up or slow down the process of coastal erosion

Construction works – speed up

Dredging – speed up

Constructing groynes to trap sand

and rock debris and others - slow

down

COASTAL STUDIES

Types of COASTAL PROCESSES?

1. Erosion2. Transportation3. Deposition

Coastal erosional processes:-

1. Corrasion2. Attrition3. Solution4. Hydraulic action

CASH

Factors influencing the rate of erosion:-

1. Type of wave2. Nature of coastal rocks3. The gradient of the

coast4. Impact of human activities

Types of WAVES?

1. Constructive waves

2. Destructive waves