Chapter 7 – Natural Hazards and Disasters Questions and Answers: NCERT Solutions for Class 11 Geography(India Physical Environment)

1. Choose the right answer from the four alternatives given below.
Question 1(i).
Which one of the following states of India experiences floods frequently?
(a) Bihar
(b) West Bengal
(c) Assam
(d) Uttar Pradesh.

Answer:
(c) Assam

Question 1(ii).
In which one of the following districts of Uttaranchal did Malpa Landslide disaster take place?
(a) Bageshwar
(b) Champawat
(c) Almora
(d) Pithoragarh.

Answer:
(d) Pithoragarh.

Question 1(iii).
Which one of the following states receives floods in the winter months?
(a) Assam
(b) West Bengal
(c) Kerala
(d) Tamil Nadu.

Answer:
(d) Tamil Nadu.

Question 1(iv).
In which of the following rivers is the Majuli River Island situated?
(a) Ganga
(b) Brahmaputra
(c) Godavari
(d) Indus.

Answer:
(b) Brahmaputra

Question 1(v).
Under which type of natural hazards do blizzards come?
(a) Atmospheric
(b) Aquatic
(c) Terrestrial
(d) Biological.

Answer:
(a) Atmospheric

2. Answer the following questions in less than 30 words.
Question 2(i).
When can a hazard become a disaster?

Answer:
A hazard becomes a disaster when either there are no mitigating circumstances to prevent the disaster from happening or the mitigating circumstances fail. For example, if there are floods which lead to great loss of life and property, it will be called disaster. But if through GPS, it was pre-informed and evacuation was successful, it will be a hazard but not a disaster.

Question 2(ii).
Why are there more earthquakes in the Himalayas and in the north-eastern region of India?

Answer:
Indian plate is moving at a speed of one centimetre per year towards the north and northeastern direction and this movement of plates is being constantly obstructed by the Eurasian plate from the north. As a result of this, both the plates are said to be locked with each other resulting in accumulation of energy at different points of time. Excessive accumulation of energy results in building up of stress, which ultimately leads to the breaking up of the lock and the sudden release of energy causes earthquakes along the Himalayan arch.

Question 2(iii).
What are the basic requirements for the formation of a cyclone?

Answer:
Following are the basic requirements for the formation of cyclones:
Large and continuous supply of warm and moist air that can release enormous latent heat.
Strong Coriolis force that can prevent filling of low pressure at the centre because absence of Coriolis force near the equator prohibits the formation of tropical cyclone between 0°-5° latitude.
Unstable condition through the troposphere that creates local disturbances around which a cyclone develops.
Absence of strong vertical wind wedge, which disturbs the vertical transport of latent heat.

Question 2(iv).
How are the floods in Eastern India different from the ones in Western India?

Answer:
Important rivers of Eastern India are Brahmaputra, Ganga, Damodar, Mahanadi, Krishna, Kaveri, Godavari. In western India, important rivers are Luni, Mahi, Narmada and Tapti. In eastern India floods occur more frequently as compared to Western India because more rainfall takes place in eastern India as compared to western India. Moreover, floods of eastern India are more severe in comparison of western India floods.

Question 2(v).
Why are there more droughts in Central and Western India?

Answer:
In central and western India less rainfall takes place. Due to this, water scarcity takes place. Less rainfall, excessive evaporation, scarcity in ground water and water bodies create conditions of drought. Western India consists of deserts and central India has plateaus and in both regions ground water level is less. It creates drought conditions.

3. Answer the following questions in not more than 125 words.
Question 3(i).
Identify the Landslide-prone regions of India and suggest some measures to mitigate the disasters caused by these.

Answer:
Highly unstable, relatively young mountainous areas in the Himalayas and Andaman and Nicobar, high rainfall regions with steep slopes in the Western Ghats and Nilgiris, the north-eastern regions, along with areas that experience frequent ground-shaking due to earthquakes, etc. and areas of intense human activities, particularly those related to construction of roads, dams, etc. are highly prone to landslides.
Areas that have almost similar conditions to those included in the very high vulnerability zone are also included in this category. The only difference between these two is the combination, intensity and frequency of the controlling factors. All the Himalayan states and the states from the north-eastern regions except the plains of Assam are included in the high vulnerability zones.
Subsidence are most common in states like Jharkhand. Orissa, Chhattisgarh, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Goa and Kerala.
Measures for Mitigation
Promoting large-scale afforestation programmes.
Construction of bunds to reduce the flow of water.
Terrace farming should be encouraged in the north-eastern hill states.
Restriction on the construction and other developmental activities such as roads and dams, limiting agriculture to valleys and areas with moderate slopes, and control on the development of large settlements in the high vulnerability zones, should be enforced.

Question 3(ii).
What is vulnerability? Divide India into natural disaster vulnerability zones based on droughts and suggest some mitigation measures.

Answer:
Vulnerability refers to the risk of becoming a victim to a disaster. Those areas which are more prone to natural calamities are more vulnerable.
On the basis of severity of droughts, India can be divided into the following regions:
1. Extreme Drought Affected Areas: Most parts of Rajasthan, particularly areas to the west of the Aravali hills, i.e. Marusthali and Kachchh regions of Gujarat fall in this category. Included here are also the districts like Jaisalmer and Barmer from the Indian desert that receive less that 90 mm average annual rainfall.
2. Severe Drought Prone Area: Parts of eastern Rajasthan, most parts of Madhya Pradesh, eastern parts of Maharashtra, interior parts of Andhra Pradesh and Karnataka Plateau, northern parts of interior Tamil Nadu and southern parts of Jharkhand and interior Odisha are included in this category.
3. Moderate Drought Affected Area: Northern parts of Rajasthan, Haryana, southern districts of Uttar Pradesh, the remaining parts of Gujarat, Maharashtra except Konkan, Jharkhand and Coimbatore plateau of Tamil Nadu and interior Karnataka are included in this category. The remaining parts of India can be considered either free or less prone to the drought.
Remedial Measures
Provision for the distribution of safe drinking water, medicines for the victims and availability of fodder and water for the cattle and shifting of the people and their livestock to safer places, etc.
Identification of ground water potential in the form of aquifers, transfer of river water from the surplus to the deficit areas, and particularly planning for inter-linking of rivers and construction of reservoirs and dams, etc.
Remote sensing and satellite imageries can be useful in identifying the possible river-basins that can be inter-linked and in identifying the ground water potential.
Rainwater harvesting can also be an effective method in minimising the effects of drought.

Question 3(iii).
When can developmental activities become the cause of disasters?

Answer:
Development has created many such problems whereby disasters occur. There are some activities carried by human beings that are directly responsible for disasters.
Industrial development: Bhopal Gas tragedy, Chernobyl nuclear disaster, wars, release of CFCs (Chlorofluorocarbons) etc are examples where industrial development has created disasters.
Pollution: Increase of green house gases, environmental pollutions like noise, air, water and soil are some of the disasters which are caused directly by human actions.
Deforestation: There are some other activities of human beings that accelerate or intensify disasters indirectly. Landslides and floods due to deforestation, unscientific land use and construction activities in fragile areas are some of the disasters that are the results of indirect human actions.

Multiple Choice Questions

Question 1.
Rapid sliding of large mass of bedrocks is called:
(a) Erosion
(b) Earthquake
(c) Tsunami
(d) Landslides.

Answer:
(d) Landslides.

Question 2.
In how many regions has India been divided on the basis of proneness to earthquake?
(a) Five Regions
(b) Seven Regions
(c) Eight Regions
(d) Ten Regions.

Answer:
(a) Five Regions

Question 3.
From the point of view of earthquake, which areas of India are most vulnerable?
(a) Northern Himalayas and Kachchh
(b) North-eastern India
(c) Northern Plains
(d) Peninsular India.

Answer:
(a) Northern Himalayas and Kachchh

Question 4.
Natural calamities which cause heavy loss to life and property are called:
(a) Famine
(b) Disaster
(c) Calamity
(d) None of these.

Answer:
(b) Disaster

Question 5.
The centre of the cyclone is mostly a warm and low-pressure, cloudless core known as:
(a) Storm Surge
(b) Eye of the storm
(c) Cyclone
(d) Jet Stream.

Answer:
(b) Eye of the storm

Question 6.
Which regions have highest number of landslides?
(a) Plateau regions
(b) Mountainous regions
(c) Coastal Regions
(d) Desert regions.

Answer:
(b) Mountainous regions

Question 7.
Which region of India is most prone to drought?
(a) Rajasthan
(b) Andhra Pradesh
(c) Tamil Nadu
(d) Coastal Regions.

Answer:
(a) Rajasthan

Question 8.
Natural changes which have side effects on human life are called:
(a) Common Hazards
(b) Manmade hazards
(c) Natural Hazards
(d) None of the above.

Answer:
(c) Natural Hazards

Question 9.
Which of the following is not a natural calamity?
(a) Earthquake
(b) Drought
(c) Fire Borne
(d) Tsunami.

Answer:
(c) Fire Borne

Question 10.
Which of the following is not a flood prone area?
(a) Assam
(b) West Bengal
(c) Bihar
(d) Rajasthan.

Answer:
(d) Rajasthan.

Question 11.
Which of the following is not a earthquake prone area?
(a) Jammu and Kashmir
(b) Himachal Pradesh
(c) Uttarakhand
(d) East Coast.

Answer:
(d) East Coast.

Question 12.
Which of the following is not a landslide-prone area?
(a) Himalayas and Andaman and Nicobar
(b) Steep slopes in the Western Ghats
(c) Nilgiris in the north-eastern regions,
(d) Aravali regions in Rajasthan.

Answer:
(d) Aravali regions in Rajasthan.

Question 13.
Which of the following is not a type of drought?
(a) Meteorological Drought
(b) Agricultural Drought
(c) Hydrological Drought
(d) Desert Drought

Answer:
(d) Desert Drought

Very Short Answer Type Questions

Question 1.
What are natural calamities?

Answer:
Natural calamities are elements of circumstances in the Natural environment that have the potential to cause harm to people or propertv or both.

Question 2.
Name some common natural calamities.

Answer:
Some important natural disasters are earthquake, floods, tsunamis, drought, landslides, cyclones, volcanoes, tornado, hailstorms, dust storms, hurricanes, etc.

Question 3.
What is a disaster?

Answer:
Disaster is an undesirable occurrence resulting from forces that are largely outside human control, strikes quickly with little or no warning, which causes or threatens serious disruption of life and property including death and injury to a large number of people, and requires therefore, mobilisation of efforts in excess of that which are normally provided by statutory emergency services.

Question 4.
What is the unit of measuring earthquake?

Answer:
Richter scale is the unit of measuring earthquake.

Question 5.
Name the states of India having high risk of earthquake.

Answer:
Areas of North-eastern states, Darbhanga and Araria along the Indo- Nepal border in Bihar, Uttarakhand, Western Himachal Pradesh and Kashmir Valley in the Himalayan region and the Kutch (Gujarat), Northern parts of Punjab, Eastern parts of Haryana, Delhi, Western Uttar Pradesh, and Northern Bihar fall under the High Damage Risk Zone.

Question 6.
Mention the speed of cyclones.

Answer:
Cyclones move with a speed of 20 km per hour. As it moves further, its energy keeps on reducing. Its duration is 5 to 7 days.

Question 7.
Name flood prone areas of India.

Answer:
Assam, West Bengal and Bihar are among the high flood-prone states of India. Apart from these, most of the rivers in the northern states like Punjab and Uttar Pradesh are also vulnerable to occasional floods.

Question 8.
Mention three causes due to which flood affected areas have increased in India.

Answer:
Three causes due to which flood affected areas have increased in India:
Deforestation
Barrier in flow of water by means of transport and buildings.
Construction of dams.

Question 9.
What is disaster management?

Answer:
Disaster management is inclusive of all those processes and preparations which are undertaken to mitigate the losses from disasters. It includes steps that should be taken before disaster, during disaster and after disaster.

Question 10.
On the basis of origin, in how many groups are calamities categorized?

Answer:
On the basis of origin, natural disasters have been classified into four groups:
1. Atmospheric: Thunderstorm, Tornado, Drought, Hailstorm
2. Terrestrial: Earthquake, Volcanic Eruption, Avalanches, Soil Erosion
3. Aquatic: Floods, Tidal Waves, Storm Surge, Tsunami
4. Biological: Viral Diseases, Plants and Animals as colonisers.

Question 11.
National Institute of Disaster Management, have made an intensive analysis of more than 1,200 earthquakes that have occurred in India in different years in the past and has divided into how many zones?

Answer:
National Geophysical Laboratory, Geological Survey of India, Department of Meteorology, Government of India, along with the recently formed National Institute of Disaster Management, have made an intensive analysis of more than 1,200 earthquakes that have occurred in India in different years in the past, and based on these, they divided India into the following five earthquake zones:
1. Very high damage risk zone
2. High damage risk zone
3. Moderate damage risk zone
4. Low damage risk zone
5. Very low damage risk zone.

Question 12.
Expand IDNDR.

Answer:
International Decade for Natural Disaster Reduction.

Question 13.
How can we control floods?

Answer: Construction of flood protection embankments in the flood-prone areas, construction of dams, afforestation and discouraging major construction activities in the upper reaches of most of the flood-creating rivers, etc. are some measures to control floods.

Short Answer Type Questions

Question 1.
What is a landslide? What are its effects on human life?

Answer:
A form of mass movement in which rock and debris moves rapidly down the slope under the influence of gravity as a result of failure along a shear plane.
It affects human life quite adversely:
It leads to floods.
It leads to loss of life and property.
It leads to failure of transport and communication system.
It leads to hurdles in economic activities and destruction of natural beauty.

Question 2.
What are the conditions for cyclone?

Answer:
Following are the basic requirements for the formation of cyclones:
Large and continuous supply of warm and moist air that can release enormous latent heat.
Strong Coriolis force that can prevent filling of low pressure at the centre because absence of Coriolis force near the equator prohibits the formation of tropical cyclone between 0°-5° latitude.
Unstable condition through the troposphere that creates local disturbances around which a cyclone develops.
Absence of strong vertical wind wedge, which disturbs the vertical transport of latent heat.

Question 3.
Give measures to mitigate the impact of cyclones.

Answer:
Following measures can be taken to mitigate the impact of cyclones:
We need to improve our Geographical Positioning System (GPS) to provide timely information;
Construction of dams, coast lines and water bodies.
Planting of trees in coastal areas;
By providing beforehand information.

Question 4.
How can we mitigate the effect of earthquakes?

Answer:
We can take following steps to mitigate the effect of earthquake:
Establishing earthquake monitoring centres for regular monitoring and fast dissemination of information.
Use of Geographical Positioning System (GPS).
Preparing a vulnerability map of the country and dissemination of vulnerability risk information.
Modifying the house types and building-designs in the vulnerable areas and discouraging construction of high-rise buildings, large industrial establishments and big urban centres in such areas.

Question 5.
Explain the effects of landslides.

Answer:
Effects of landslides are as follows:
Landslides have relatively small and localised area of direct influence, but roadblock, destruction of railway lines and channel- blocking due to rock-falls have far-reaching consequences.
Diversion of river courses due to landslides can also lead to flood and loss of life and property.
It also makes spatial interaction difficult, risky as well as a costly affair, which, in turn, adversely affects the developmental activities in these areas.

Question 6.
Explain the effects of drought.

Answer:
Droughts has many side effects:
It leads to shortage of food grains, fodder and water.
It leads to crop failure creating scarcity of food grains (akal), fodder (trinkal), inadequate rainfall, resulting in shortage of water (jalkal).
Large-scale death of cattle and other animals, migration of humans and livestock.
Scarcity of water compels people to consume contaminated water resulting in spread of many waterborne diseases like gastro-enteritis, cholera, hepatitis, etc.

Question 7.
How can we mitigate the effects of floods?

Answer:
We can mitigate the effects of floods in the following ways:
Dams are built along rivers to regulate the flow of water.
Connect with hydroelectric power plants.
Rivers should be dredged and their beds need to be laid deeper.
Reservoirs are built to hold back water and control the flow of small rivers.

Question 8.
Discuss socio-environmental effects of earthquake.

Answer:
Following are the socio-environmental effects of earthquake.
Surface waves produce fissures on the earth’s surface. Earthquakes are responsible for landslides and often these cause obstructions in the flow of rivers and channel resulting in the formation of reservoirs.
It not only damages and destroys the settlements, infrastructure, transport and communication network, industries and other developmental activities but also robs the population of their material and socio-cultural gains that they have preserved over generations.
It renders them homeless, which puts an extra-pressure and stress, particularly on the weak economy of the developing countries.

Question 9.
What are the ways to mitigate instances of landslides?

Answer:
It is always advisable to adopt area- specific measures to deal with landslides,
Restriction on the construction and other developmental activities such as roads and dams, limiting agriculture to valleys and areas with moderate slopes, and control on the development of large settlements in the high vulnerability zones, should be enforced.
Some positive actions like promoting large-scale afforestation programmes and construction of bunds to reduce the flow of water should be taken.
Terrace farming should be encouraged in the north-eastern hill states.

Question 10.
Explain the spatial distribution of tropical cyclones in India.

Answer:
Owing to its Peninsular shape surrounded by the Bay of Bengal in the east and the Arabian Sea in the west, the tropical cyclones in India also originate in these two important locations.
Most of the cyclones originate between 10°-15° north latitudes during the monsoon season.
The Bay of Bengal cyclones mostly develop during the months of October and November.
They originate between 16°-2° N latitudes and to the west of 92° E.
By July, the place of origin of these storms shifts to around 18° N latitude and west of 90°E near the Sunderban Delta.

Question 11.
Differentiate between:
1. Natural Hazards and Natural Disaster.
2. Manmade disaster and Natural

Answer:
1.
Basis
Natural Hazards
Natural disaster
Meaning
Natural Hazards are elements of circumstances in the Natural environment that have the potential to cause harm to people or property or both.
Natural Disaster is an undesirable occurrence resulting from forces that are largely outside human control, strikes quickly with little or no warning, which causes or threatens serious disruption of life and property including death and injury to a large number of people, and requires therefore, mobilisation of efforts in excess of that which are normally provided by statutory emergency services.
Scope
Every natural hazard is not a disaster.
Every natural disaster is a natural hazard.
Example
USA facing -50 degree temperature every year. It is a hazard but due to preparedness, it never becomes a disaster.
Tsunami occurred in 2004 proved to be a great disaster.
2.
Basis
Manmade Disaster
Natural disaster
Meaning
Manmade disasters are undesirable occurrences resulting from human actions.
Natural Disaster is an undesirable occurrence resulting from forces that are largely outside human control, strikes quickly with little or no warning, which causes or threatens serious disruption of life and property.
Example
Bomb blast, industrial explosions, wars, fire accidents, etc.
Earthquake, landslides, cyclones, floods, droughts, etc.

Long Answer Type Questions

Question 1.
Explain about different types of drought.

Answer:
Different types of droughts are as follows:
Meteorological Drought: It is a situation when there is a prolonged period of inadequate rainfall marked with mal-distribution of the same over time and space.
Agricultural Drought: It is also known as soil moisture drought, characterised by low soil moisture that is necessary to support the crops, thereby resulting in crop failures. Moreover, if an area has more than 30 percent of its gross cropped area under irrigation, the area is excluded from the drought-prone category.
Hydrological Drought: It results when the availability of water in different storages and reservoirs like aquifers, lakes, reservoirs, etc. falls below what the precipitation can replenish.
Ecological Drought: When the productivity of a natural ecosystem fails due to shortage of water and as a consequence of ecological distress, damages are induced in the ecosystem. Various parts of India experience these droughts recurrently which result in some serious socio-economic and ecological problems.

Question 2.
On the basis of past experiences, frequency and certain causal relationships with the controlling factors like geology, geomorphic agents, slope, land-use, vegetation cover and human activities, India has been divided into how many zones?

Answer:
On the basis of past experiences, frequency and certain causal relationships with the controlling factors like geology, geomorphic agents, slope, land-use, vegetation cover and human activities, India has been divided into a number of zones.
1. Very High Vulnerability Zone: Highly unstable, relatively young mountainous areas in the Himalayas and Andaman and Nicobar, high rainfall regions with steep slopes in the Western Ghats and Nilgiris, the north-eastern regions, along with areas that experience frequent ground-shaking due to earthquakes, etc. and areas of intense human activities, particularly those related to construction of roads, dams, etc. are very highly vulnerable.
2. High Vulnerability Zone: Areas that have almost similar conditions to those included in the very high vulnerability zone are also included in this category. All the Himalayan states and the states from the north-eastern regions except the plains of Assam are included in the high vulnerability zones.
3. Moderate to Low Vulnerability Zone: Areas that receive less precipitation such as Trans-Himalayan areas of Ladakh and Spiti, undulated yet stable relief and low precipitation areas in the Aravali, rain shadow areas in the Western and Eastern Ghats and Deccan plateau also experience occasional landslides. Landslides due to mining and subsidence are most common in states like Jharkhand, Orissa, Chhattisgarh, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Goa and Kerala.
4. Other Areas: The remaining parts of India, particularly states like Rajasthan, Haryana, Uttar Pradesh, Bihar, West Bengal, Assam and Coastal regions of the southern States are safe as far as landslides are concerned.