NCERT Solutions for Class 11 Geography Chapter 21 - Natural Hazards and Disasters

Question 1:

Which state suffers from most of floods?

  1. Bihar
  2. West Bengal
  3. Assam
  4. Uttar Pradesh

(a). Bihar

Question 2:

In which district of Uttrakhand did the Malpa landslide take place?

  1. Bageshwar
  2. Champanat
  3. Almora
  4. Pithoragarh

(d). Pithoragarh

Question 3:

Which state gets floods in winter months?

  1. Assam
  2. West Bengal
  3. Kerala
  4. Tamil Nadu

(d). Tamil Nadu

Question 4:

In which River bed is Maujauli River island located?

  1. Ganga
  2. Brahmaputra
  3. Godavari
  4. Indus

(b). Brahmaputra

Question 5:

Under which type of natural hazards, do Blizzards occur?

  1. Atmospheric
  2. Hydrologic
  3. Geomorphologic
  4. Biological

(a). Atmospheric

Question 6:

When can a hazard become a disaster?


Generally a hazard and a disaster have the same meaning. Both of these cause harm to people and property. When a hazard occurs on a large scale and occurs suddenly, it causes harm to a large population. It is then called a disaster.

Question 7:

Why are these more earthquakes in the Himalayas and in the north-eastern region of India?


Himalayas and N.E. hilly region are earthquake prone areas. It is due to the fact that Indian plate is moving northward at the rate of 1 cm per year. The Indian plate collides with the Eurasian plate, with the result earthquakes occur along the Himalayan arc.

Question 8:

What are the basic requirements for the formation of a cyclone?


(a) Hot wet air.
(b) Intense corriolis force
(c) Instability in troposphere
(d) Absence of strong vertical currents.

Question 9:

How are floods in Eastern India different from the areas in Western India?


There is heavy rainfall in Eastern India. The rivers are over flooded and water spreads in the form of floods. But in Western India, there is sudden heavy rainfall which results in flood in some areas.

Question 10:

Why are there more droughts in Central and Western India?


There in high variability of rainfall in these areas. It is more than 40% therefore, droughts occur when there is no rainfall for a long period.

Question 11:

Identify the landslide prone region of India and suggest some measures to mitigate the disasters caused by these.


Landslide is the rapid sliding of large mass of bed rocks down the slope. Landslides are generally controlled by regional or localised factors. Hence gathering information and monitoring the possibilities of landslide in not only difficult by also costly.
Main Areas. Landslide controlling factors are geology, geomorphic agents, slope, land use, vegetation cover and human activities. India has been divided into a number of zones.
Landslide Vulnerability 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 included in this zone.
(2) High Vulnerability Zone : All the Himalayan states and union territories and the states from the northeastern region 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 (Himachal Pradesh), 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, Odisha, Chhattisgarh, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Goa and Kerala.
Other Areas : The remaining parts of India, particularly states like Rajasthan, Haryana, Uttar Pradesh, Bihar, West Bengal (except district Darjeeling), Assam (except district Karbi Anglong) and Coastal regions of the Southern States are safe as far as landslides are concerned.
It is always advisable to adopt are-specific
measures to deal with landslides.
(a) Restriction on the construction and other developmental activities such as roads and dams,
(b) 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.
(c) This should be supplemented by some positive actions like promoting large-scale afforestation programmes and construction of bunds to reduce the flow of water.
(d) Terrace farming should be encouraged in the north– eastern hill states where Jhumming (Slash and Burn/ Shifting Cultivation) is still prevalent.

Question 12:

What is vulnerability? Divide India into natural vulnerability zones based on droughts and suggest some mitigation measures.


Due to low rainfall and high variability of rainfall, some regions are likely to suffer from droughts. This is called natural vulnerability.
The term ‘drought’ applied to an extended period when there is a shortage of water availability due to inadequate percipitation, excessive rate of evaporation and overutilisation of water from the reservoirs and other storages, including the ground water.
Drought Prone Areas in India
Indian agriculture has been heavily dependent on the monsoon rainfall. Droughts and floods are the two accompanying features of Indian climate. According to some estimates, nearly 19 per cent of the total geographical area of the country and 12 per cent of its total population suffer due to drought every year. About 30 per cent of the country’s total area is identified as drought prone affecting around 50 million people. It is a common experience that while some parts of the country reel under floods, there are regions that face severe drought during the same period. Moreover, it is also a common sight to witness that one region suffers due to floods in one season and experiences drought in the other. This is mainly because of the large-scale variations and unpredictability in the behaviour of the moonsoon in india. Thus, droughts are widespread and common phenomena in most parts of the country, but these are most recurrent and severe in some and not so in others. 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. Mitigation of Droughts. Planning for droughts should consider social and physical environment.
(i) 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. are some steps that need to be taken immediatley.
(ii) Identification of ground water potentital in the form of aquifers, transfer of river water from the surplus to the deflelt areas, and particularly planning for interlinking of rivers and construction of reservoirs and dams, etc. should be given a serious thought.
(iii) 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.
(iv) Dissemination of knowledge about droughtresistant crops and proper training to practise the same can be some of the long-term measures that will be helpful in drought-mitigation.
(v) Rainwater harvesting can also be an effective method in minimising the effects of drought.

Question 13:

When can developmental activities become the cause of disasters?


Natural forces are not the only causes of disasters. Disasters are also caused by some humn activities. There are some activities carried by human beings that are directly responsible for disasters. Bhopal Gas tragedy, Chernobyl nuclear disaster, wars, release of CFCs (Chlorofluorocarbons) and increase of greenhouse gases, environmental pollutions like noise, air, water and soil are some of the disasters which are caused directly by human actions. 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. It is a common exerience that human-made disasters have increased both in their numbers and magnitudes over the years and concerted efforts are on at various levels to prevent and minimise their occurrences.
Establishment of National Institute of Disaster Management, India, Earth Summit at Rio de Janeiro, Brazil, 1993 and the World Conference on Disaster Management in May 1994 at Yokohama, Japan, etc. are some of the concerete steps towards this direction initiated at different levels.
Consequently, now human beings tend to intensify their activities into disaster prone areas increasing their vulnerability to disasters. Colonisation of flood plains of most ofthe rivers and development of large cities and port-towns like – Mumbai and Chennai along the coast, and touching the shore due to high land values, make them vulnerable to the occurrence of cyclones, hurricanes and tsunamis.