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