NCERT Solutions for Class 11 Geography Chapter 7 Natural Hazards and Disasters

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 7 Natural Hazards and Disasters Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

Natural Hazards and Disasters NCERT Solutions for Class 11 Geography Chapter 7

Natural Hazards and Disasters Questions and Answers Class 11 Geography Chapter 7

Question 1.
Choose the right answer from the four alternatives given below :
(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

(ii) In which one of the following districts of Uttranchal did Malpa landslide disaster take place?
(G) Bageshwar
(b) Almora
(c) Champawat
(d) Pithoragarh
Answer:
(d) Pithoragarh

NCERT Solutions for Class 11 Geography Chapter 7 Natural Hazards and Disasters

(iii) Which one of the following states receives floods in the winter month?
(a) Assam
(b) West Bengal
(c) Kerala
(d) Tamil Nadu
Answer:
(d) Tamil Nadu

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

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

NCERT Solutions for Class 11 Geography Chapter 7 Natural Hazards and Disasters

Question 2.
Answer the following questions in less than 30 words :
(i) When can a hazard become a disaster?
Answer:
Hazards and disasters are closely related. Hazard is a threat while disaster is an event. Natural hazards that cause great loss of human life and economy are called disasters and catastrophers while disaster is an extraordinary event of limited duration which causes serious disruption of economy of the country.

(ii) Why are there more earthquakes in the Himalayas and in the north-eastern region of India?
Answer:
The earthquakes in the Himalayan region are tectonic in origin. Because the Indian plate is moving at a speed of one centimetre per year towards the north and north-eastern 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 locked with each other resulting in accumulation of energy at different points of time. Excessive accumulation of energy results in the development of stress which causes breaking up of rocks and sudden release of energy causes earthquakes along the Himalayan arc and north-east.

(iii) What are the basic requirements for the formation of a cyclone?
Answer:
The basic requirements for the formation of a cyclone :

  1. Temperature of the oceanic surface over 26°C.
  2. Appearance of a closed isobar.
  3. Pressure dropping below lOOOmb.
  4. Areas of circular movement, first spreading to a radius of 30-50 km, then increasing gradually to 100-200 km. and even to 1000 km.
  5. Vertically the wind speed first rising to a height of 6 km, then much higher.

NCERT Solutions for Class 11 Geography Chapter 7 Natural Hazards and Disasters

(iv) How are the floods in eastern India different from the ones in western India?
Answer:
Floods occur due to :

  • Excessive rainfall by the south-west monsoon, tropical cyclones in the pre and post monsoon period.
  • Silting of river beds.
  • Deforestation and changes in the river courses.

All factors are favourable in eastern India. Therefore, flood in eastern India is different from the one in western India.

(v) Why are there more droughts in thecentral and western India?
Answer:
The central and western India i.e. Rajasthan, west of Aravali Hills, Kachchh region of Gujarat, Jaisaimer and Barmer receive less than 90 mm. average annual rainfall. So that there are more droughts.

Question 3.
Answer the following questions is not more than 125 words :
Identify the Landslide-prone regions of India and suggest some measures to mitigate the disasters caused by these.
Answer:
Landslide is the rapid sliding of large mass of bedrocks or regolith. On the basis of frequency and eertain casual relationship with the controlling factors like geology, geomorphic agents, slope, landuse, vegetation cover and human activities, India has been divided into the following landslide prone-regions:
(i) Very high Vulnerability Zone-The Himalayas and Andaman and Nicobar, high rainfall regions, north-eastern regions, along with areas that experience frequent ground shading.

(ii) High Vulnerability Zone – All Himalayan stateS Juid states from the north eastern regions except the plains of Assam.

(iii) Moderate to Low Vulnerability Zone – Areas that receive less precipitation such as trans-Himalayan areas of Ladakh and Spiti (Himachal Pradesh). Land-slides due to mining are most common in the states like Jharkhand, Orissa, Chattisgarh, Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu, Goa and Kerala.

Measures to mitigate the disaster caused by landslide :

(i) Afforestation – The planting of trees and other vegetation on hill slopes and uncultivated land is helpful in controlling landslides to some extent.

(i) Restricted grazing of animals – Restricted grazing of animals should be practiced in order to minimise the loss of plant cover.

(iii) Terracing – Terracing is cutting the hill slopes in a series of large steps made up of flat fields. Terracing is also effective in checking the landslides.

NCERT Solutions for Class 11 Geography Chapter 7 Natural Hazards and Disasters

Question 4.
What is vulnerability? Divide India into natural disaster vulnerability zones based on droughts and suggest some mitigation measures.
Answer:
Vulnerability – The disasters are sudden and violent, different social groups gets affected and respond to it differently. The difference in their ability to cope up with disasters is known as vulnerability, poor people are more vulnerable than the rich due to their lower tolerance capabilities.

Disasters are the result of harmful attacks brought against human beings by external agents. Drought is shortage of water due to inadequate precipitation and excessive rate of evaporation. Droughts and floods are the two accompanying features of Indian climate, about 30% of country’s total area is identified as drought vulnerized area.

There is large-scale variation and unpredictability in the behaviour of the monsoon in India. On the basis of severity of droughts, India can be divided into the following vulnerability zones:

(i) Extreme Vulnerability Zone – Most parts of Rajasthan,particularly areas to the west of Aravali Hills and Kachchh region of Gujarat, Jaisalmer and Barmer from Indian desert that receive less than 90 mm. average annual rainfall.

(ii) Severe Drought Vulnerability Zone – Parts of eastern Rajasthan, most of Andhra Pradesh and Karnataka Plateau, northern parts of interior Tamil Nadu and southern parts of Jharkhand and interior Orissa.

(iii) Moderate Drought Vulnerability Zone – Northern parts of Rajasthan, Haryana, southern districts of Uttar Pradesh, remaining parts of Gujarat, Maharashtra except Konkan, Jharkhand and Coimbatore plateau of Tamil Nadu.

Mitigation measures
The following steps to be taken for the drought mitigation programme:

  • Provision for the distribution of safe drinking water, medicines for the victims and availability of fodder and water for the cattle.
  • Shifitingofthepeopleandtheirlivestocktosaferplacesneedto be done.
  • Identification of ground water potential, transfer of river water from the surplus to the deficit areas (planning for inter-linking of rivers).
  • Construction of reservoirs and dams.
  • Remotesensingandsateiliteimageriescanbehelpfiilinidentifying the river basin.
  • To provide proper training to practise the drought-resistant crops.
  • Rainwater harvesting can also be an effective method in minimising the effects of droughts.

NCERT Solutions for Class 11 Geography Chapter 7 Natural Hazards and Disasters

Question 5.
When can developmental activities become the cause of disasters?
Answer:
Disasters are also caused by some human activities. There are some activities that are directly responsible for man-made disasters :

  • Bhopal gas tragedy, chernobyl nuclear disaster, wars, release of CFC’s(chlorofluorocarbons).
  • Increase of greenhouses gases, environmental pollution like noise, air, water and soil pollution.
  • Landslides and floods due to deforestation.
  • Unscientific land use and construction activities in fragile areas.
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