NCERT Solutions for Class 11 Geography Chapter 6 - Natural Hazards and Disasters

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66. 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

(d) Uttar Pradesh

Ans. (c) Assam

(ii) In which one of the following districts of Uttaranchal did Malpa landslide disaster take place?

(a) Bageshwar

(b) Champawat

(d) Pithoragarh

Ans. (d) Pithoragarh

(iii) Which one of the following states receives floods in the winter months?

(a) Assam

(b) West Bengal

(d) Tamil Nadu

Ans. (d) Tamil Nadu

(iv) In which of the following rivers is the Majuli River Island situated?

(a) Ganga

(b) Brahmaputra

(d) Indus

Ans. (b) Brahmaputra

(v) Under which type of natural hazards do blizzards come?

(a) Atmospheric

(b) Aquatic

(d) Biological

Ans. (a) Atmospheric

67. Answer the following questions in less than 30 words.

(i) When can a hazard become a disaster?

Ans. A hazard becomes a disaster when there are no mitigating circumstances to prevent the disaster from happening or the mitigating circumstances fail. For instance, flooding that results in significant loss of life and property is referred to be a disaster. However, if the evacuation was effective and GPS forewarned it, it would only be a hazard, not a disaster.

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

Ans. The Indian plate moves one centimetre per year in a northerly and northeasterly direction, but the Eurasian plate continually blocks this movement from the north. As a result, it is stated that both plates are locked against one another, causing energy to build up at certain periods in time. Extreme energy buildup causes tension to accumulate, which in turn causes the lock to break and the abrupt release of energy to create earthquakes along the Himalayan arch.

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

Ans. Following are the basic requirements for the formation of cyclones:

(a) An abundant supply of warm, humid air with the potential to release a lot of latent heat.

(b) Strong Coriolis force can prevent the centre of a low-pressure system from filling up, as the absence of Coriolis force near the equator prevents tropical cyclone development between latitudes 0° and 5°.

(d) The absence of a strong vertical wind wedge disturbs the vertical transport of latent heat.

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

Ans. The Brahmaputra, Ganga, Damodar, Mahanadi, Krishna, Kaveri, and Godavari are significant rivers in eastern India. The Luni, Mahi, Narmada, and Tapti rivers are significant ones in western India. As a result of the greater amount of rainfall in eastern India compared to western India, floods there happen more frequently in eastern India. Additionally, compared to floods in western India, eastern India floods are more severe.

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

Ans. Less rain falls in western and central India. As a result, there is a shortage of water. Conditions of drought are brought on by a lack of precipitation, high rates of evaporation, and a lack of surface and groundwater. In both of these regions, the groundwater table is low. Western India is made up of deserts, and central India contains plateaus. It creates drought conditions.

68. Answer the following questions in not more than 125 words.

(i) Identify the Landslide-prone regions of India and suggest some measures to mitigate the disasters caused by these.

Ans. 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.

High Vulnerability Zone: All the Himalayan states and the states from the north-eastern regions except the plains of Assam are included in the high vulnerability zones.

Moderate to Low Vulnerability Zone: Areas that receive less precipitation such as Trans Himalayan areas of Ladakh and Spiti (Himachal Pradesh), low precipitation areas in the Aravali, rain shadow areas in the Western and Eastern

Ghats and Deccan plateau also experience occasional landslides.

Measures for Mitigation:

(a) Promoting large-scale afforestation programmes.

(b) Construction of bunds to reduce the flow of water.

(d) Restricting 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.

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

Ans. 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 the severity of droughts, India can be divided into the following regions:

(a) Extreme Drought Affected Areas: Most parts of Rajasthan, particularly areas to the west of the Aravali hills, i.e., Marusthali and Kutch regions of Gujarat, fall in this category. The districts like Jaisalmer and Barmer from the Indian desert are included here and receive less than 90 mm average annual rainfall.

(b) 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.

(c) 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 free or less prone to drought.

Remedial Measures:

(a) Provision for the distribution of safe drinking water, medicines for the victims, availability of fodder and water for the cattle, and shifting of the people and their livestock to safer places, etc.

(b) Identification of groundwater potential in 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.

(c) Remote sensing and satellite imageries can help identify the possible river basins that can be interlinked and in identifying the groundwater potential.

(d) Rainwater harvesting can also be an effective method of minimising the effects of drought.

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

Ans. Development has created many such problems whereby disasters occur. Some activities carried by human beings are directly responsible for disasters.

(a) Industrial development: Bhopal Gas tragedy, Chornobyl nuclear disaster, wars, release of CFCs (Chlorofluorocarbons) etc are examples where industrial development has created disasters.

(b) Environmental pollution, such as noise, air, water, and soil pollution, as well as an increase in greenhouse gases, are some of the calamities that are directly attributable to human activity and this development

(c) Other human actions, such as deforestation, might indirectly hasten or exacerbate disasters. Disasters caused by indirect human activity include landslides and floods brought on by deforestation, irresponsible land use, and construction projects in vulnerable locations.