Natural Hazards and DisastersClass 11 India Physical Environment NCERT Solutions
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Q11. 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
Solution
Answer: (c) Assam
Explanation: The source material states, "Assam, West Bengal and Bihar are among the high flood-prone states of India." It further highlights the serious consequences of frequent inundation in Assam due to the flooding of the Brahmaputra river. While all the listed states are prone to floods, Assam is repeatedly mentioned for its high frequency and severity of flooding.
Q21. Choose the right answer from the four alternatives given below.
(ii) In which one of the following districts of Uttaranchal did Malpa Landslide disaster take place?
(a)
Bageshwar
(b)
Champawat
(c)
Almora
(d)
Pithoragarh
Solution
Answer: (d) Pithoragarh
Explanation: While the main text does not specify the location of the Malpa landslide, this event is listed as a project topic. The Malpa landslide disaster occurred in the Pithoragarh district of Uttaranchal (now Uttarakhand) in August 1998.
Q31. Choose the right answer from the four alternatives given below.
(iii) Which one of the following states receives floods in the winter months?
(a)
Assam
(b)
West Bengal
(c)
Kerala
(d)
Tamil Nadu
Solution
Answer: (d) Tamil Nadu
Explanation: The text explicitly mentions, "Sometimes, Tamil Nadu experiences flooding during November-January due to the retreating monsoon." This period corresponds to the winter months in India.
Q41. Choose the right answer from the four alternatives given below.
(iv) In which of the following rivers is the Majuli River Island situated?
(a)
Ganga
(b)
Brahmaputra
(c)
Godavari
(d)
Indus
Solution
Answer: (b) Brahmaputra
Explanation: According to the chapter, "Majuli (Assam), the largest riverine island in the world, is the best example of good paddy crops after the annual floods in Brahmaputra."
Q51. Choose the right answer from the four alternatives given below.
(v) Under which type of natural hazards do blizzards come?
(a)
Atmospheric
(b)
Aquatic
(c)
Terrestrial
(d)
Biological
Solution
Answer: (a) Atmospheric
Explanation: Table 6.1, which classifies natural disasters, lists blizzards under the 'Atmospheric' category, along with other weather-related phenomena like thunderstorms, cyclones, and tornadoes.
Q12. Answer the following questions in less than 30 words.
(i) When can a hazard become a disaster?
Solution
A natural hazard becomes a disaster when it strikes a vulnerable area and causes large-scale, widespread death, loss of property, and severe disruption to social systems and life. Essentially, it is when the magnitude of destruction and damage is very high and exceeds the coping capacity of the affected community.
Q22. Answer the following questions in less than 30 words.
(ii) Why are there more earthquakes in the Himalayas and in the north-eastern region of India?
Solution
The Himalayas and the north-eastern region of India experience more earthquakes because they are located at the tectonic boundary where the Indian plate is moving northwards and colliding with the Eurasian plate. This collision results in the accumulation and sudden release of immense energy, causing frequent seismic activity along this Himalayan arch.
Q32. Answer the following questions in less than 30 words.
(iii) What are the basic requirements for the formation of a cyclone?
Solution
The basic requirements for the formation of a tropical cyclone are:
- A large and continuous supply of warm and moist air.
- Strong Coriolis force to prevent the filling of low pressure at the center.
- Unstable atmospheric conditions through the troposphere.
- Absence of a strong vertical wind wedge.
Q42. Answer the following questions in less than 30 words.
(vi) How are the floods in Eastern India different from the ones in Western India?
Solution
Floods in Eastern India, such as in Assam and Bihar, are typically widespread riverine floods caused by the overflow of large river systems during the monsoon. In contrast, floods in Western India, such as in Rajasthan and Gujarat, are often flash floods resulting from high-intensity rainfall over a short period and blockage of drainage channels.
Q52. Answer the following questions in less than 30 words.
(v) Why are there more droughts in Central and Western India?
Solution
Central and Western India experience more droughts primarily due to the large-scale variations and unpredictability of the monsoon rainfall. Regions like western Rajasthan and Gujarat receive very low annual rainfall, while other areas in this zone suffer from inadequate and erratic precipitation, leading to recurrent drought conditions.
Q13. 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.
Solution
Landslide-Prone Regions:
India's landslide-prone regions are categorized based on their vulnerability:
- Very High Vulnerability Zone: This includes the highly unstable, young mountains of the Himalayas and Andaman and Nicobar Islands, high-rainfall areas with steep slopes in the Western Ghats and Nilgiris, and the north-eastern regions.
- High Vulnerability Zone: This zone covers almost all the Himalayan states and the states of the north-eastern region (except the plains of Assam).
- Moderate to Low Vulnerability Zone: This includes the Trans-Himalayan areas of Ladakh and Spiti, the Aravali hills, rain shadow areas of the Western and Eastern Ghats, and areas affected by mining in states like Jharkhand and Odisha.
Mitigation Measures:
To mitigate landslide disasters, the following area-specific measures are suggested:
- Restrict construction of roads, dams, and large settlements in high-vulnerability zones.
- Promote large-scale afforestation programs and construct bunds to reduce the flow of water.
- Encourage terrace farming in hill states like those in the northeast to replace shifting cultivation (Jhumming).
- Limit agricultural activities to valleys and areas with moderate slopes.
Q23. Answer the following questions in not more than 125 words.
(ii) What is vulnerability? Divide India into natural disaster vulnerability zones based on droughts and suggest some mitigation measures.
Solution
Vulnerability:
Vulnerability refers to the susceptibility of a community or region to the impact of a hazard. It is a condition resulting from physical, social, economic, and environmental factors that increase the potential for loss and damage when a hazard occurs. For example, colonizing a flood plain increases a community's vulnerability to floods.
Drought Vulnerability Zones in India:
- Extreme Drought Affected Areas: Most parts of Rajasthan west of the Aravalli hills (Marusthali) and the Kachchh region of Gujarat.
- Severe Drought Prone Area: Includes eastern Rajasthan, most of Madhya Pradesh, eastern Maharashtra, interior parts of Andhra Pradesh and Karnataka Plateau, and parts of Tamil Nadu, Jharkhand, and Odisha.
- Moderate Drought Affected Area: Covers northern Rajasthan, Haryana, southern Uttar Pradesh, and the remaining parts of Gujarat, Maharashtra, and Karnataka.
Mitigation Measures:
- Immediate Measures: Provision of safe drinking water, medicines, fodder for cattle, and shifting people and livestock to safer areas.
- Long-term Measures: Identifying groundwater potential through remote sensing, planning for inter-linking of rivers, constructing reservoirs and dams, promoting drought-resistant crops, and implementing rainwater harvesting techniques.
Q33. Answer the following questions in not more than 125 words.
(iii) When can developmental activities become the cause of disasters?
Solution
Developmental activities can become the cause of disasters when they are carried out without considering the environmental balance, especially in fragile ecosystems. Such activities can either directly cause man-made disasters or increase the vulnerability of a region to natural hazards.
Examples include:
- Directly Caused Disasters: Industrial accidents like the Bhopal Gas tragedy and environmental pollution from the release of harmful substances are direct results of human activities.
- Intensifying Natural Hazards:
- Deforestation and unscientific construction in hilly areas can lead to landslides and increase flood intensity.
- Colonisation of flood plains and river-beds for agriculture and settlement exposes a large population to river floods.
- Construction of large cities and ports like Mumbai and Chennai on coastlines makes them highly vulnerable to cyclones and tsunamis.
- Mining activities can cause land subsidence, a form of disaster.
Thus, when development ignores natural limits and processes, it transforms natural hazards into large-scale disasters by increasing human exposure and weakening the environment's resilience.