Chapter: Environmental Science and Engineering

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Disaster Management

It is defined as the geological process and it is an event concentrated in time and space in which a society or subdivision of a society undergoes severe danger and causes loss of its members and physical property.

DISASTER MANAGEMENT

Hazard

It is a perceived natural event which threatens both life and property.

 

Disaster

 

ü   A disaster is the realization of this hazard


ü   It is defined as the geological process and it is an event concentrated in time and space in which a society or subdivision of a society undergoes severe danger and causes loss of its members and physical property.

 

Types

 

Natural disasters – refers to those disasters that are generated by natural phenomena. Man made disasters – refers to the disasters resulting from man made hazards.

 

 

1 FLOODS

 

Whenever the magnitude of water flow exceeds the carrying capacity of the channel within its banks the excess of water overflows on the surroundings causes floods.

 

Causes of floods

 

Ø   Heavy rain, rainfall during cyclone causes floods

 

Ø   Sudden snow melt also raises the quantity of water in streams and causes flood

 

Ø   Sudden and excess release of impounded water behind dams

 

 

Ø   Clearing of forests for agriculture has also increased severity of floods.

 

Flood Management

 

·        Encroachment of flood ways should be banned.

·        Building walls prevent spilling out the flood water over flood plains.

 

·        Diverting excess water through channels or canals to areas like lake, rivers where water is not sufficient.

 

·        Optical and microwave data from IRS is also used for flood management.

·        Flood forecasts and flood warning are also given by the central water commission.

 

 

2 CYCLONES

 

It is a meteorological process, intense depressions forming over the open oceans and moving towards the land.

 

Cyclone is measured by Saffir-Simpson scale.


 

1 Effect

 

ü   The damage depends on the intensity of cyclone the damage to human life, crops, roads, transport, could be heavy.

ü   Cyclone occurrence slows down the developmental activities of the area.

 

Table 2.1 Classification of cyclones based on their speed

 

 

 

2 Cyclone management

 

Ø   Satellite images are used by meteorological departments for forecasting the weather conditions which reveal the strength and intensity of the storm.

Ø   Radar system is used to detect the cyclone and is being used for cyclone warning.


3 Case studies

Cyclone in Orissa – 1999

 

ü   Two cyclones in Orissa occurred on 18th and 29th October 1999.In the coastal area of Orissa, a powerful cyclone storm hit with a wind velocity of about 260 km/hr. Nearly 14-30 districts of Orissa were in severe damage.


ü   It has been reported that nearly 15 millions of people were affected and 90-95% of the crop yield was affected. About 11,500 local schools have been damaged.


 

3 LAND SLIDES

 

The movement of earthy materials like coherent rock, mud, soil and debris from higher to lower region to gravitational pull is called land slides.

 

1 Causes

v   Movement of heavy vehicles on the unstable sloppy regions.


v   Earthquake, shocks, vibrations and cyclone.


2 Effects of landslides

1. Block roads and diverts the passage.

2. Soil erosion increases.

 

2. Causes damages to houses, crops and live stock.

 

 

 

4 EARTH QUAKES

 

An earthquake is a sudden vibration caused on earth surface with the sudden release of tremendous energy stored in rocks under the earth’s crust.

 

1 Causes

1. Disequilibrium in any part of the earth crust

2. Underground nuclear testing

2. Decrease of underground water level.

 

2 Severity of an earthquake:

Generally it is measured by its magnitude on Richter scale.


 

3 Effect

·        Damage the settlements and transport systems

·        Collapses houses and their structures

·        Deformation of ground surface

·        Tsunami

 

 

4 Earthquake Management

 

ü   Constructing earthquake resistant building


ü   Wooden houses are preferred


ü   Seismic hazard map should give the information about the magnitude of intensity of anticipated earthquakes.

 

 

5 TSUNAMI

 

A tsunami is a large wave that is generated in a water body when the seafloor is deformed by seismic activity. This activity displaces the overlying water in the ocean.

 

Causes of tsunami

 

v   Seismic activities like earthquakes, landslides, volcanic eruptions, explosions, can generate tsunami.

v   Deformation of the sea floor due to the movement of plates.

 


Concept of Tsunami

A tsunami is not a single wave but a series of waves like the ordinary waves which we see on

 

seas.

 

Effects on Tsunami

 

§    Tsunami attacks mostly the coastlines, causing devastating property, damage and loss of life.


§    Tsunami can kill lot of human beings, livestock’s.


§    Tsunami may also spread lot of water borne diseases.


Tsunami Management

ü   Earthquakes under the water are monitored by sensors on the floor of the sea.


ü   The sensors send the information of floating buoys on the surface, whenever they detect any changes in pressure of the sea.


ü   The information is then relayed to satellites, which passes it on to the earth stations.


ü   Finally the country make the people alert through the media to take all necessary precautions.


Case studies

Tsunami- Japan 2011, India 2004.


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