Coastal erosion

Coastal erosion

1. COASTAL EROSIONCOASTAL EROSION
Presented by
PRAMODA G
Geology, 4
th
semester
DoS In Earth Science,
University of Mysore

2. CONTENTS CONTENTS
Introduction
Shoreline
Beach
Tides,Waves & Currents
Coastal dynamics
Erosion
Deposition
Depositional land forms
Rate of destruction of coast
Conclusion
Reference

3. INTRODUCTIONINTRODUCTION
 A coastline or seashore is the area where land
meets the sea or ocean.
Coastal erosion is the wearing away of land and the
removal of beach or dune sediments by wave action,
tidal currents, wave currents… etc.

4. SHORELINESHORELINE
A shore or shoreline is the fringe of land at the
edge of a larger body of water, such as an ocean,
sea, or lake.

5. Coastal ClassificationCoastal Classification
•A Primary Coast is a coast which is essentially in
the same condition when sea level stabilized after
the last ice age.
•Terrestrial (land) influences dominate Primary
Coast

o Land erosion coast
o Volcanic coast
o Ice coast
I.Primary Coast

6. II. Secondary coastII. Secondary coast
o Wave erosion coast
o Marine deposition coasts
oCoasts built by organisms
 0
Secondary coasts is shaped primarily by marine agents
or by marine organisms. May or may not have been
primary coasts before being shaped by the sea.

7. EROSIONAL & DEPOSITIONAL EROSIONAL & DEPOSITIONAL
COASTCOAST
EROSIONAL COASTS are those that developed
where active erosion by wave action occurs or
where rivers or glaciers caused erosion when sea
level was lower than it presently is; these include
cliffs or rocky shores.
DEPOSITIONAL COASTS develop where sediments
accumulate either from a local source or after being
transported to the area in rivers and glaciers or by
ocean currents and waves; these include deltas,
mangrove swamps, salt marshes, barrier islands,
and beach-sand dunes

8. BEACHBEACH
A beach is a landform along the shoreline of an
ocean or sea. It usually consists of loose particles
which are often composed of rock, such as sand,
gravel, shingle, pebbles or cobblestones.

Kaup Beach, Karnataka Kovalam Beach, Trivandrum

9. Typical Beach ProfileTypical Beach Profile

10. WAVES
Waves are the forward movement of the ocean's
water due to the oscillation of water particles by the
frictional drag of wind over the water's surface.
Wind-generated waves provide most of the energy
for erosion, transportation, and deposition of
sediment.

11. TIDES
Tides are the rise and fall of sea levels caused by the
combined effects of the gravitational forces exerted by
the Moon and the Sun and the rotation of the Earth.
They affect coasts in two major ways:
(1) by initiating a rise and fall of the water level
(2) by generating tidal currents.

12. OCEAN CURRENT
An ocean current is a continuous, directed
movement of ocean water generated by the forces
acting upon this mean flow, such as wind, Coriolis
effect, temperature and salinity differences
and tides caused by the gravitational pull of
the Moon and the Sun.

13. COASTAL DYNAMICSCOASTAL DYNAMICS
Coastal dynamic is the change of coast.
Costal dynamics includes erosion, transportation
& deposition by waves, tides, currents…etc
Currents, waves and winds constantly affect the
margins of land adjacent to bodies of water. These
processes differ along the various types of coasts
and in diverse climates.
Coasts are composed of many kinds of materials,
including sand, rocky sediments, mud and
biological substances. Because of these variations,
coasts respond differently to the natural forces
acting upon them.

14. Movement of sand on the beachMovement of sand on the beach
Movement perpendicular (↕) to shoreline
◦Caused by breaking waves
◦Light wave activity moves sand up the beach
face toward the berm
◦Heavy wave activity moves sand down the beach
face to the longshore bars
◦Produces seasonal changes in the beach

15. Summertime and wintertime Summertime and wintertime
beach conditionsbeach conditions
Summertime beach Wintertime beach

16. Movement of sand on the beachMovement of sand on the beach
Movement parallel (↔) to shoreline
◦Caused by wave refraction (bending)
◦Each wave transports sand either upcoast or
downcoast
◦Huge volumes of sand are moved within the surf
zone
◦The beach resembles a “river of sand”

17. Longshore current and Longshore current and
longshore driftlongshore drift
Longshore current – a net movement of water
parallel to the shoreline.
Longshore drift - movement of sediment caused
by longshore current

18. EROSIONEROSION
Erosion is the process by which materials are removed
from the surface and transported to another location.
Coastal erosion is the wearing away of land and the
removal of beach or dune sediments by wave action, tidal
currents, wave currents.

19. Features of Erosional ShoresFeatures of Erosional Shores
Headland
Wave-cut
cliff
Sea cave
Sea arch
Sea stack
Marine
terrace

20. Sea CaveSea Cave
Cala Gonone coast, Sardinia, Italy

21. Sea stack and Sea ArchSea stack and Sea Arch
Old Harry Rocks, England.
The Green Bridge of Wales

22. DEPOSITIONDEPOSITION
Material that is transported by the waves along a
coastline is eventually deposited forming
distinctive deposition features.

23. Features of depositional shoresFeatures of depositional shores
Spit
Bay barrier
Tombolo
Barrier island
Delta

24. SPITSSPITS
Spits are long narrow ridges of sand and shingle
which project from the coastline into the sea. The
formation of a spit begins due to a change in the
direction of a coastline - the main source of
material building up a spit is from long shore drift
which brings material from further down the
coast.
Farewell Spit , New Zealand’

26. TOMBOLOTOMBOLO
Tombolos are formed where a spit continues
to grow outwards joining land to an offshore
island

27. The Angel Road of Shodo Island, Japan

28. BARRIER ISLANDSBARRIER ISLANDS
Barrier Islands, a coastal landform and a type of
barrier system, are relatively narrow strips of sand
that parallel the mainland coast. They usually occur
in chains, consisting of anything from a few islands
to more than a dozen
Topsail Island, North Carolina, USA

29. Ganges delta, India

30. RATE OF DESTRUCTION RATE OF DESTRUCTION
OF COASTOF COAST
Rate of destruction(weathering) along the coast is due to
human activity and also due to natural agencies.
Rate of destruction is not uniform in all coasts. Rate of
destruction is controlled by several factors, that are
1.slope of the coast
2.intensity of waves & tides
3.wind velocity
4.topography of coast(sandy, rocky…etc)

31. Habitat Destruction along the coast and in the ocean
resulting from harmful fishing practices (dynamite
fishing)and other human activities such as mining.
 Destroyed habitats include sea grasses, marshes, corals
and mangroves – all of which are important nurseries for
fish and critical for buffering coasts from storm damage.

Damaging habitat can lead to increased erosion and
sedimentation, increased impact from storms.

32. CONCLUSIONCONCLUSION
Coastal processes are highly unpredictable.
Costal dynamics includes erosion, transportation &
deposition by waves, tides, currents…etc.
Erosional activity along coastal may lead to the
formation of typical landforms like sea stacks,
arches, caves.
Deposition of the transported sediments will lead to
formation of tombolo, spit, barrier island.
Rate of destruction is not uniform in all coasts. Both
natural and human activities increase the rate of
destruction.

33. REFERENCEREFERENCE
Thornbury, W. D. (2004). Principles of
Geomorphology, CBS Publishers & Distributors Pvt.
Ltd., pp. 420-443.
G.B.Mahapatra.(2004). Text Book of Physical
Geology, CBS Publishers & Distributors Pvt. Ltd., pp
296-314.
Parbin Singh.(2008).Engineering & General Geology,
S.K.Kataria & Sons, pp 81-88
Websites
http://quizlet.com/1330440/ocean-ch-10-the-coast-
beaches-and-shoreline-processes-key-terms-flash-
cards/
http://en.wikipedia.org/wiki/Coastal_landform