1.Explain the effects of floods?what are measures taken to mitigate this
disaster?
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flood is a natural event that can have far reaching effects on people and the
environment. Simply a flood is too much water in the wrong place. Physically a flood is
a high flow of water, which over tops either the natural or the artificial banks of a river.
Flood may occur due to the following causes
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Prolonged rainfall over large drainage basins.
High intensity rainfall is mainly associated with more localized, conventional
storms etc.
Melting snow is responsible for wide spread flooding.
Flood can have severe consequences and can have effects on the economy,
environment and people.
Economic
During floods, roads, bridges, farms, houses, and automobiles are
destroyed. People become homeless. Additionally government deploys firemen, police
and other emergency apparatuses to help the affected. All these come at a heavy cost to
people and government. It usually takes years for affected communities to be rebuilt
and business to come back to normalcy.
Environment
The environment also suffers when floods happen. Chemicals and other
hazardous substances end up in the water and eventually contaminate the water bodies
that floods end up in. In 2011, a huge tsunami hit Japan and sea water flooded a part of
the coastline. The flooding caused massive leakage in nuclear plants and has since
caused high radiation in that area. Authorities in Japan fear that Fukushima radiation
levels are 18 times higher than even thought.
Additionally flooding causes kills animals and other insects are
introduced to affected areas, distorting the natural balance of the ecosystem.
People and animals
Many people and animals have died in the flash floods. Many more are
injured and others made homeless. Water supply and electricity are disrupted and
people struggle and suffer as a result. In addition to this flooding brings a lot of diseases
and infections including military fever, pneumonic plague, dermatopathia and
dysentery. Sometimes insects and snakes make their ways to the area and cause a lot of
havoc.
Flash floods are fond in arid and semi arid zones, where there is a
combination of steep topography, little vegetation and high intensity and short duration
of rainstorms. Floods resulting from dam failures are examples of a combined natural
and technological hazard. The flood occurred in Northern India(1978) and Orissa
Floods(1955) are two among the disastrous floods of the world.
Flood control can be carried out in a scientific manner by studying the
flood plain, river catchments and meteorology of the said location. A few points to be
noted are
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Sand removal from riverbeds to be discouraged.
River alignment and bank protection to be proper.
Planting trees and reeds along the river banks.
Proper land use pattern to be adopted.
The floor level of houses must be at a level of about 1 m above MFL
The management of situations during flood are discussed below:
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The data with Meteorological departments, Irrigation dept and PWD must
be under the control of Disaster Management team.
Flood warning through electronic and print media must be broadcast.
People residing in flood prone areas must be evacuated.
They must be rehabilitated in safe places.
The places evacuated must be under police surveillance.
Floodgates of dams must be opened slowly, giving sufficient early warnings.
Riverbanks and coastal areas must be properly protected.
Health Department and Civil Supplies Departments should go to the
temporary camps and see that all the needs are satisfied.
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2 .what is earthquake?ennumerate its effects and briefly explain the
measures to be taken to mitigate this disaster?
An earthquake is a sudden shaking or trembling of the
ground produced by abrupt displacement of rock masses, usually within the upper 15 to
50 km of the earth’s crust. An earthquake is the result of a sudden release of energy in
the earth’s crust that creates seismic waves. The fastest waves are the primary waves or
compression waves travel in average crustal rocks at about 5 km per second. The
secondary waves or shear waves travel along the crust at a speed of 3 km per second.
The slowest waves are surface waves or Raleigh waves travel near the surface of the
earth less than 3 km per second.
Earthquakes are the vibrations caused by rocks breaking under stress.
The underground surface along which the rock breaks and moves is called a fault plane.
Earthquakes in Australia are usually caused by movements along the faults as a result
of compression in the earth’s crust. When two blocks of rock or two plates are rubbing
against each other, they stick a little.
Most earthquakes related to compressional or tensional stresses build up
at margins of the huge moving lithospheric plates. The immediate cause of earthquake
is the sudden release of stress along a fault. Volcanic eruptions, rock falls, landslides,
and explosions can also cause a quake, but most of these are of only local extend. Shock
waves from a powerful earthquake can trigger smaller earthquakes in a distant location
hundreds of miles away if the geologic conditions are favourable.
The energy released from an earthquake can be up to 10,000 times more
powerful than the first atomic bomb. Its side effects are can be:
Ground shaking
Shaking of the grond caused by the passage of seismic waves, especially
surface waves near the epicentre of the earthquake are responsible for the most damage
during an earthquake. The intensity of ground shaking depends on:
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Conditions of the local geology influence events
Duration and intensity of the earthquake
Distance: distance from the epicentre drops off so the intensity of the shaking
decreases
Faulting and ground rupture
When an earthquake event occurs ground rupture is only where the fault
zone moves. Structures built across these zones will collapse.
Landslides and ground subsidence
Avalanches, landslides, slumps and rock slides are triggered by ground
shaking. These landslides are more destructive than the earthquakes.
Damage to manmade structures
Damage to manmade structures such as roads, bridges, dams and
buildings from ground motion depends on the type of construction.
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Fires
Concrete and masonry structures are brittle and thus more susceptible to
damage and collapse
Damage to wood and steel structures is far less because of its flexibility
Fires often associated with broken electrical lines and gas lines, is one of
the common side effects of earthquakes. The San Francisco earthquake of 1906 caused
90% of damage by fire.
Spill of hazardous chemicals
Radioactivity from damaged nuclear power plants
Liquefaction of water-laden sediments
Ground water, sand and soil combine during seismic shaking to form
liquefaction during a moderate to powerful earthquake. A quicksand like soil is the
result of this process. When liquefaction takes place under buildings the foundation sink
and building collapse.
Flooding
Flooding can come from many sources such as broken water main pipes,
dams that fail due to the earthquake and earthquake generated tsunamis.
Injuries and death
Tsunamis
For sure one of the most dangerous effects of an earthquake is a tsunami.
These are giant waves that can cause flood and can reach up to a height of 100 feet.
Measures against earthquakes
Personal measures:
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Seek shelter under stable tables or door frames
If outside stay away from buildings, bridges and electricity pylons and move
to open areas
Avoid areas at risk from secondary processes such as landslides, rock fall and
soil liquefaction
After an earthquake check gas, water and electricity pipes and lines for
damage
Listen to the radio and follow instructions from authorities
Technical/biological measures:
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No measures can be taken to prevent earthquakes themselves, however
limited measures exist that can counteract their secondary effects like
landslides, rockfall and soil liquefaction
Earthquake proof planning and design of buildings
The microzoning of the local geological substratum provides indicators in
which tremors will have a particularly strong or attenuated effect
Organisational measures:
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At present earthquake prediction is insufficiently precise to provide with
advance warning. Measures of this nature enable numbers of human lives to
be saved
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3.what is land slide?ennumerate its effects and explain the
measures to be taken to mitigate this disaster?
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landslides are the downward and outward movement of a slope
composed of earth materials such as rock, soil, artificial fills.gravity
constantly pull downward every material everywhere on earth,causing a
variety of phenomena collectively refered to as mass wasting.in this geological
materials are removed down slope from one place to another.landslides
causes great distress as they damage property,crops and endanger life.they
mainly take place during rainy season.they block streams due to which water
overflows their banks and causes floods.
human activities such as road construction forest cleaning agricultural
cultivation and building houses on steep and unstable slope increases both
frequency and the damage done by landslides.buildings located on steep hills
of relatively unconsolidated soil are the site of large economic losses from
landslides.in some cases people are unware of the risks associated with
locating on or under unstable hillslides.mass wasting process are slow enough
that few lives are lost but property damage can be high.
human induced landslides
• during construction of roads and mining activities huge portions of fragile
mountainous areas are cut and thrown into adjacent areas and streams. •
these land masses weaken the already fragile mountain slopes and lead to
landslides called man induced landslides
causes of landslides
• removal of vegetation:-in the sloppy area creates soil erosion, which leads
to landslides • underground mining:-cause subsidence of the ground. •
transport:-due to the movement of buses and trains in the unstable sloppy
region cause landslides. • addition of weight:-addition of extra weight (or)
construction on the slope areas leads to landslide. • ground water level:-over
exploitation of ground water also leads to landslides.
harmful effect of landslides
• landslide increases the turbidity of nearby streams, thereby reducing their
productivity. • destruction of communication links. • loss of habitat and
biodiversity. • loss of infrastructure and economic loss.
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4.what is Cyclones? ennumerate its effects and explain the
measures to be taken to mitigate this disaster?
Cyclone refers to any spinning storm that rotates around a lowpressure
center. The low-pressure center is also referred to as the
'eye' of the storm, which is well known for being eerily calm
compared with the areas under the spinning 'arms' of the storm.
Severe tropical cyclones are responsible for large number of
causalities and considerable damage to property and agricultural
crop. The destruction is confined to the coastal districts and the
maximum destruction being within 100 km from the centre of the
cyclone and on the right side of the storm track.
Principal dangers from cyclones are: (i) very strong winds, (ii)
torrential rain, and (iii) high storm tides.
Most casualties are caused by coastal inundation by storm surge.
Maximum penetration of storm surges varies from 10 to 20 km
inland from the coast.
Heavy rainfall and floods come next in order of devastation. They
are often responsible for much loss of life and damage to
property.
Death and destruction directly due to winds are relatively less.
The collapse of buildings, falling trees, flying debris, electrocution,
aircraft and ship accidents and disease from contaminated food
and water in the post-cyclone period also contribute to loss of life
and destruction of property.
This abnormal rise in sea level caused by cyclone is known as
storm surge. The surge is generated due to interaction of air, sea
and land.
The cyclone provides the driving force in the form of very high
horizontal atmospheric pressure gradient and very strong surface
winds.
As a result, the sea level rises and continues to rise as cyclone
moves over increasingly shallower water as it approaches coast,
and reaches a maximum on the coast near the point of landfall
(Point of crossing coast).
Surge is maximum in the right forward sector of the cyclone and
about 50100 Km from the centre coinciding with the zone of
 maximum wind. Winds in this sector are from ocean to land.
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5 .write a short note on environmental impact assessment?
Environmental impact assessment is the formal process used to predict the
environmental consequences(positive or negative) of a plan, policy, program or project
prior to the decision to move forward with the proposed action. EIA is an important
management tool for ensuring optimal use of natural resources for sustainable
development. To facilitate collection of environmental data and preparation of
management plans, guidelines have been evolved and circulated to the concerned
Central and State Government Departments.
There are 5 broad stages to this process:
Screening
Determining whether a proposed project falls within the remit of the regulations,
whether it is likely to have a significant effect on theenvironment and therefore
requires an assessment.
Scoping
Determining the extend of issues to be considered in the assessment and reported in the
Environmental Statement. The applicant can ask the local planning authority for their
opinion on what information needs to be included.
Preparing an Environmental statement
Where it is decided that an assessment is required, the applicant must compile the
information reasonably required to assess the likely significant environment effects of
the development. To help the applicant public authorities must make available any
relevant environmental information in their possession. The information finally
compiled by the applicant is known as environmental statement.
Making a planning application and consultation
The Environmental Statement must be publicised. The statutory consultation bodies
and the public must be given an opportunity to give their views about the proposed
development and the environmental statement.
Decision making
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The Environmental statement together with any other information which is
relevant to the decision, commends and representations made on it, must be
taken into account by the local planning authority.
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