Erosion is when wind,  water, and ice take sediments away. Erosion on coasts by wind and water. Water is major agent of erosion. About 21% of all erosion in done by coastal erosion.

1. AUTHOR: PARTHA DAS SHARMA, E.mail: sharmapd1@gmail.com,
Website: http://saferenvironment.wordpress.com

2. COASTAL EROSION
1. Coastal Processes.
2. Coastal Land forms
3. Impacts and Hazards on Coasts.
4. Prevention Methods used.

3. Coastal Erosion
Erosion is when wind, water, and ice take
sediments away.
Erosion on coasts by wind and water.
Water is major agent of erosion.
About 21% of all erosion in done by coastal
erosion.
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4. Coastal Processes
Currents and Waves.
Swash and Backwash of waves.
Tides and Tidal Currents.
Rip Currents.
Long Shore drift.
Hurricanes and Tsunami.
Abrasion & Attrition.
Corrosion (Salutation).
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5. Waves and Currents
A wave is a disturbance
that propagates through
space and time.
Current is a continuous
flow of water in a
particular direction.
Both contains
characteristics of Crest
and Trough.
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6. Swash and Back wash
Swash is the water
that washes up on
shore after an
incoming wave has
broken.
Also called as
constructive current.
Backwash current is a
seaward current that
results from the
receding swash.
Also called destructive
current.
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7. Swash and Back wash
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8. Tides and Tidal currents
Tidal bulge combine with
daily earth’s rotation
creates broad system of
waves.
Cause by the gravitational
action.
Mainly because of moon
and sun.
Incoming tides and out
going tides.
Neap and Lunar tides.
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9. Rip Currents
Fast, narrow surface
currents.
Flow seaward at nearly
right angles to shore.
Mainly in surfing zone.
Move back to sea by
narrow paths.
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10. Long Shore Drift
The movement of
sediments along a
beach or shore by
currents.
Having a particular
direction.
Mainly cause by Long
shore currents.
Swash and Backwash
are major Phenomena.
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11. Hurricane and Tsunami
Hurricane
A tropical cyclonic storm
with winds having speed
>120km/hour.
Mostly hit in late summers
and fall.
Tsunami
A short period disturbance
create by submarine earth
quake or volcanic vent.
The waves more than
100feet, might possibly
rise.
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12. Abrasion & Attrition(Corrasion)
Abrasion.
The waves pick up the
sediment & hurl it
against the cliffs (uses
the sediment as
ammunition).
Attrition
As the sediment is
hurled against the cliff,
bits are chipped off,
the sediment gets
smaller & rounder
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13. Corrosion (Salutation)
Salt & other
chemicals in sea
water attack &
dissolve the cliffs.
The cliffs mainly of
limestone and
calcium rich are
mainly effected.
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14. Coastal Land Forms.
Headlands and Bay Mouth Bars.
Barrier islands and Barrier Reef.
Atolls and Reef Flats.
Fore shore and Back shore.
Berms and Spits.
Cliffs, Crack or Inlet.
Caves and Arches.
Stack and Stump.
Wave Cut Platform
Tombolos
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15. Headlands and Bay mouth Bars.
Headlands
A headland is an area of
land adjacent to water on
three sides.
Where the rock is hard a
Headland is left
outstanding.
Bay mouth bars
A shallow bar, extends
partially or completely
across the mouth of bay.
Where there is softer rock
erosion carves out a bay.
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16. Barrier Island and Barrier Reef
Barrier Island
Elongate ridges of sand
and gravel parallel to
coasts, forms at long
shallow shelf.
Separated from mainland
by shallow lagoon.
Barrier Reef
Coral reef that parallel to
shore.
Separated by open water.
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17. Atolls and Reef Flats.
Atoll
A ring shaped coral
reef, encloses a lagoon.
Grows upward from
submerged volcanic
peak.
Reef Flats
A platform of coral
fragments and sands.
Exposed only in low
tidal zone.
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18. Fore Shore and Back Shore.
Fore shore is the shore between low and high tide lines.
This area continuously attacked by currents and waves.
Back shore is the inner portion of the shore that is land
ward having gentle sloping.
It is only attacked by waves during high tides and in
severe storms.
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19. Berms and Spits
Berms
Horizontal portion of a
beach whose edge
abruptly slopes seaward.
Located in Back shore
zone.
Spits
A narrow strip of land,
usually of sand.
Whose one end attached
with mainland and ends
in water.
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20. Cliffs, Crack or inlet
A cliff is a steep, often
vertical, rock outcrop
along a coast.
The waves erode the rock
through processes such
as hydraulic action and
corrosion.
Wave attack picks out
cracks, joints &
weaknesses in the cliff.
With time these
weaknesses are widened,
to form inlets or Goes
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21. Caves and Arches.
The inlets with
time further
opened due to
action of currents
and waves form
Caves.
The hole broken
through the rock
makes an arch
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22. Stack and Stump.
A pillar of rock
surrounded by sea is
left as a stack.
Pressure is put on the
arch roof until it
collapses.
Waves undercut the
base of the stack until
only a rock stump is
left.
Stump then disappears
later on due to wave
attacks
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23. Wave cut Platform
The cliff above the
wave cut notch
eventually collapses
leaving the cliff further
back.
Repeat this process &
a wave cut platform is
left at the cliff foot,
indicating retreat
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24. Tombolos
Derived from an Italian
word means"long
chain of rocks “.
It is a deposition
landform in which an
island is attached to
the mainland by a
narrow piece of land
such as a spit or bar.
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25. Impacts and Hazards on Coasts
Plate Tectonic Impacts.
Due to the movement and collision of
Plates.
Human made impacts.
Due to Man made artificial structure
and human activity.
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26. Plate Tectonic Impacts
Divergent/Convergent plate
boundaries possess steep
continental shelves
Passive Continental Margins-
have broad continental shelves
and have beaches with spit
Island Arcs can protect coastlines
Allows deltas to form
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27. Human Impacts on Coastline
Retention walls, groins, and
Revetments all cause large bulk
deposition of sediment somewhere.
Other areas lose beach sand
Development destroys vital shoreline
vegetation
Water and petroleum pumping cause
subsidence
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28. Hazards Related to Coasts
Mass wasting.
Danger to Urbanization.
Danger to Marine life.
Permanent Changes in Topography.
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29. Mass Wasting.
1. Include mainly land slide.
Land slide causes the sediments to erode in a large bulk.
Triggered due to hurricanes, Tsunamis.
Results are heavy loss of property.
2. Process of Rock fall.
When a hard cliff is under cut by waves the bulk of rocks fall
under the influence of gravity.
The Speed of fall might exceeds about 500km/hour.
Cause structures to subside and heavy turbulence in water.
Triggered coastal floods.
3. Toppling.
Rotation of a mass of rock, debris, or earth outward from a steep
slope face is called Toppling.
Toppling also produce turbidity and might also destroy structures
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30. Danger to Urbanization
Heavy loss of property taken place every year.
Loss of life also taken place.
Oil spillage during extreme storms may also cause various
diseases.
Sea water intrusions with drinking water bodies also a
major hazard
Different under ground structures might become exposed
and become collapsed.
The Most Effected urban countries of world is Holland and
Japan.
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31. Danger to Marine life.
The marine life specially the shelf marine
life heavily suffer.
Due to continuous erosion the shelf life
heavily buried inside and become extinct,
Oil spillage near shore destroy the coral
reefs and other biodiversities.
The production rate also disturbed as the
eco system changes with coastal processes.
Every year about 24-29% of all marine life
near coast effected by various coastal
factors.
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32. Permanent Changes in Topography
The continuous erosion move the shelf further
landward.
The artificial constructed structure don’t control the
rate of sediments.
A large bulk of sediments erodes from one side and
deposited at some other side, disturbing Isostacy.
The artificial structures restrict the natural land forms.
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33. Prevention Methods Used.
Structural Measures.
Non-Structural Measures
Bio Shield Methods
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34. Structural Measures.
Sea walls.
Groins.
Jetties.
Bulkheads
Revetments.
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35. Sea walls
In order to stop high tides
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36. Groins
It is oriented perpendicular to shore
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37. Jetties
On the both side of inlets
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38. Revetments
Stop the erosion
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39. Bulk Heads
They also used for steep slope stability
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40. Non Structural Measures
Building sand
dunes and growing
vegetation around
them.
Artificial beach
nourishment
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41. Coastal Dunes
Vegetation, wind-flow and
sand transportation are all
inter-dependant in the coastal
dune environment.
Air movement and not water
movement form the coastal
dune, unlike most coastal
features, and is therefore
quite unique.
The coastal dune is
characterised by an interaction
between sand transport by the
wind and vegetation cover.
Under both natural and human
induced circumstances the
dune can become unstable,
and this can lead to coastal
erosion.
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42. Bio Shields
• Mangroves
• Coral reefs
• Sea grass
• Sea weeds
• Animal habitats
• Marine parks
• Marine sanctuaries
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