1. COASTAL
STUDIES
 FACTORS
influencing the RATE
OF EROSION
TYPES OF
WAVES

2. TYPES OF WAVES

3. CONSTRUCTIVE
WAVES

4. 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

5. DESTRUCTIVE WAVES

6.  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

7. Coastal processes
EROSION
TRANSPORTATIONDEPOSITION

8. COASTAL
EROSIONAL
PROCESSES
CORRASION
(or ABRASION)
ATTRITION
SOLUTION (or
CORROSION)
HYDRAULIC
ACTION

9. C A S H

10. CORRASION (or ABRASION)
 When materials carried by
waves are thrown repeatedly against a
coast, they gradually erode the coast

11. 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

12. 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.

13. HYDRAULIC ACTION
 The force of moving
water currents rushing into a
crack in the rock face or cliff
face

15. FACTORS
influencing THE
RATE OF EROSION
TYPE OF WAVE
NATURE OF
COASTAL ROCKS
THE GRADIENT
OF THE COAST
IMPACT OF
HUMAN
ACTIVITIES

16. TYPE OF WAVE
Destructive waves cause MORE
EROSION that constructive
waves – have a more powerful
backwash than swash

17. 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

18. THE GRADIENT OF THE COAST
Coasts with a STEEPER GRADIENT
tend to COLLAPSE FASTER

19. 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

20. COASTAL
STUDIES
Types of COASTAL PROCESSES?
1. Erosion
2. Transportation
3. Deposition
Coastal erosional processes:-
1. Corrasion
2. Attrition
3. Solution
4. Hydraulic action
CASH
Factors influencing the rate of
erosion:-
1. Type of wave
2. Nature of coastal rocks
3. The gradient of the coast
4. Impact of human activities
Types of WAVES?
1. Constructive waves
2. Destructive waves