2. COAST OR BAYBAYIN
is part of the land near the sea. Contains some of the worlds
sensitive and threatened ecosystem such as mangroves, beach
forests, seagrass, and coral reefs.
3. MARINE SYSTEM
are the largest of Earth’s aquatic ecosystem. Includes
nearshore systems and extends outward from the coast to
include offshore system.
4. COASTAL PROCESSES
are events happening in the marine environment. Includes
waves, tides, sea level change, crustal movement and storm
surge.
5. COASTAL HAZARDS
caused by different coastal processes that expose marine
environment to risk of property damage, loss of life, and
ecological degradation.
8. SUBMERSION
movement of coastal sediments from the visible portion of
a beach to the submerged nearshore region of the coast.
9. SALTWATER INTRUSION
is the movement of saltwater into the freshwater aquifier.
Aquifier is an underground layer of permeable rock, gravel, sand, or silt.
12. MITIGATION METHOD
Maintaining plant cover- results to improved vegetation
Monitoring and assessment- ensures effective management of
case
Regulation of Laws
Artificial Recharge- pumps water to aquifier
13. MITIGATION METHOD
Engineering Structures
Jetties- prevent coastal erosion by promoting beach build-up
as they trap sand.
Groins/Stone Barriers - keeps sand from eroding
Breakwaters - constructed along coasts to prevent further
advancement of saltwater.
14. Advantages
• It helps in avoiding build up of unwanted sediments by collecting
sand on one side of it before it reaches the structure.
• It provide platform for ship to load and unload the material
• Prevents harbors from building up with sediments
Kerala, kollam port
15. Disadvantages
• It increases deposition on one side and the other side will
erode and narrow the beach.
Grays Harbor:
before jetty construction
in 1900
Grays Harbor:
after jetty construction
in 1999
16. Seawall
A seawall is a hard structure constructed parallel to the
coastline that reduce the effects of strong waves and to
defend the coast around a town from sea erosion.
• Investigation of the area, soil stability should be considered.
• The walls can be sloping, vertical
(10-15 m high) or curved to reflect wave power.
• The 1/3 of the wall is made as its basement.
• And also these are stepped permeable or impermeable.
• These are concrete, steel sheet pile, rock or massive rigid
masonry.
18. Advantages
• Provide good protection to property.
• May provide direct boat access to the shore.
• Fair ease of repair.
Disadvantages
• Must be well engineered for wave forces.
• May increase erosion immediately downdrift.
• Expensive to build.
• Often decrease size of fronting beach.
19. Groins
• Groins are impermeable structures that fingerlike,
perpendicularly to the shore which extend from backshore
into the littoral zone.
• This type of structure is easy to construct from a variety of
materials such as wood, rock or concrete, steel, bamboo
( Timber) and normally used on sandy coasts.
20. • The length elevation and space b/w groins should be designed
on the bases of local wave energy and beach slope.
• Groins are most effective where the long shore current is
predominantly in one direction.
• Groins are too long and too high tend to accelerate downdrift
erosion because they trap to much of sand.
• If they are too short or too permeable the structure is
inefficient because they trap too little sand.
• Sand deposition is greatly increased on the up-current side of
the groin
• Meanwhile on the down-current side of the groin, sand
erosion is greatly increased.
21. Advantages
• May provide angler access to deeper waters.
• May provide improved fish habitat.
• Do not reduce access to beach from upland.
Disadvantages
• Limit travel along beach.
• may increase erosion on down drift side.
22. Revetments
• Revetments are another type of hard structure of stone,
concrete built parallel to the sea or at the front of a beach to
protect the slope against wave or current–induced erosion.
23. • Revetments are used in place of bulkheads in areas with
moderate to severe wave energy.
• The most basic revetments consist of timber slants with a
possible rock infill.
• And two other types are Rigid revetments, Flexible revetments
etc.
• Waves break against the revetments, which dissipate and
absorb the energy.
• The cliff base is protected by the beach material held behind
the barriers, as the revetments trap some of the material.
• They may be watertight, covering the slope completely, or
porous, to allow water to filter through after the wave energy
has been dissipated.
24. In the fig. this rock rip rap
revetment contains a filter layer,
armor stone and toe protection to
prevent undercutting by scour.
Ullal beach, Mangalore
25. Advantages
• Result in less toe scour or depletion of fronting beach than do
seawalls.
• Initial cost is usually reasonable.
• Repair costs are usually reasonable because the whole
structure rarely fails at once.
Disadvantages
• Decrease access to beach from upload.
• May be hazardous to people walking on them.
• It is not constructed in town area.
26. Breakwaters
• Breakwaters are structures built parallel to a shoreline to
protect from the effects of weather, wave action and
longshore drift .
• Breakwaters can be floating or bottom anchored.
• Offshore breakwaters are usually built parallel to the shore,
but can be aligned at a slight angle to the shore to meet
specific wave or bottom conditions.
• Two another types of breakwaters are
Cellular steel breakwater and
Rubble mound breakwater
27. Cellular steel breakwaters can be built and
function effectively in waters up to 40 feet
deep.
Rubble-mound breakwaters can be used in
almost any depth of water and in almost any
wave climate.
28. Some Indian examples of breakwaters are…
Breakwater constructed (1991-94) to prevent sediment
entering the estuary in ULLAL Coast near
Mangalore,Karnataka.
• North breakwater : 375 m
• South breakwater : 580 m
• Entrance : 500 m
Mirya Bay in Maharastra also one another breakwater
29. Advantages
• Provide sheltered swimming.
• Beneficial effect may extend over a long.
• May improve fish habitat.
• May increase deposition, increasing beach.
Disadvantages
• Subject to foundation failures.
• May negatively affect the environment.
• May be damaged by moving ice.
• Usually very expensive to construct.
• Very difficult to repair.
30. Beach Nourishment
• Beach nourishment is one of the most popular soft engineering techniques of
coastal defense management schemes.
• Mainly, Beach Nourishment is the addition of sand and sediment to a beach
to replace sand and sediment that has been eroded away.
• It involves the transport of the “nourishment material” from one area to the
affected areas.
• The replacement sand is usually dredged up offshore and transported to the
beach.
• Offshore sand is almost always much finer grained and muddier, therefore it
erodes very quickly.
32. Advantages
• Provide more beach for shoreline recreation.
• Do not restrict access to beach.
• Long stretches of beach can be protected at lower costs than
by use of human made structures.
• Can have beneficial effects to downdrift shoreline as well as
immediate area
Disadvantages
• Increased turbidity may impair fishing.
• slowly beach sediment easily eroding by waves.
• Submerged sill may be navigation hazard.
33. Sand dune Stabilization
• Mainly, coastal sand dune are of vital importance in providing
natural protection to beaches and backshore areas from
infrequent severe storms.
• Another way is Vegetation : it can be used to encourage
dune growth by trapping and stabilizing blown sand.
34. Advantages
• May create wildlife habitat.
• Creates opportunity for nature study.
• Blends in with natural surrounding.
• Prevents flooding of inland areas.
Disadvantages
• May reduce access to beach from upland.
• May reduce view from upland areas.
35. MITIGATION METHOD
Beach Nourishment - large amount of sand is added to the
coast.
Installation of small walls and sandbags- used to counteract
waves hitting the shore
Beach dewatering - involves pumping out water from the
shore to prevent erosion
Ban of mining activities - can cause decrease pollutans
36. HERE ARE SOME WAYS TO COPE UP
WITH HAZARDS:
• Early Warning System
• Emergency Preparedness
• Infrastracture Improvement
• Community Education
• Land-Use Planning
37. HERE ARE SOME WAYS TO COPE UP
WITH HAZARDS:
• Insurance and Financial Preparedness
• Evacuation Planning
• Community Resilience
• Recovery and Rehabilitation
• Environmental Conservation
