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

These Class 11 Geography Chapter 6 solutions cover Natural Hazards and Disasters: Causes, Consequences and Management from India: Physical Environment (Unit IV), the NCERT textbook continued for the 2026–27 session. The chapter distinguishes a hazard from a disaster, classifies natural disasters, and studies the major disasters that strike India — earthquakes, tsunamis, tropical cyclones, floods, droughts and landslides — along with their causes, regional distribution, consequences and mitigation. Below you get step-by-step answers to every NCERT exercise question, plus key terms, extra practice, MCQs, Assertion–Reason questions and FAQs.

Class: 11 Subject: Geography Book: India: Physical Environment Chapter: 6 Unit: IV – Natural Hazards and Disasters Session: 2026–27
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Class 11 Geography Chapter 6 – Overview

Chapter 6 explains that change is the law of nature, but some sudden, undesirable changes — earthquakes, floods, cyclones — become disasters when they cause widespread loss of life and property beyond a community’s coping capacity. A natural hazard is an element of the environment with the potential to cause harm; a natural disaster is the actual large-scale destruction that occurs. The chapter notes that disasters arise from both natural forces and human activities (Bhopal Gas tragedy, deforestation-driven floods). It then surveys India’s major natural disasters — earthquakes (five seismic zones), tsunamis, tropical cyclones (Bay of Bengal and Arabian Sea), floods (Assam, West Bengal, Bihar), droughts (Rajasthan, Gujarat) and landslides (Himalayas, Western Ghats) — with their causes, distribution, consequences and mitigation. It closes with the three stages of disaster management — pre-disaster, during and post-disaster — and the role of the Disaster Management Bill, 2005 and the National Institute of Disaster Management.

Key Concepts & Terms

Disaster: an undesirable occurrence resulting from forces largely outside human control, striking quickly with little or no warning, causing serious disruption of life and property — including death and injury to large numbers — and requiring mobilisation of efforts beyond normal emergency services.

Natural hazard: an element or circumstance in the natural environment that has the potential to cause harm to people or property or both (e.g. steep unstable slopes, ocean currents). A hazard becomes a disaster only when it actually strikes and the scale of destruction is very high.

Classification of natural disasters (Table 6.1): Atmospheric (blizzards, cyclones, drought, hailstorm), Terrestrial (earthquakes, volcanic eruptions, landslides, avalanches), Aquatic (floods, tidal waves, storm surge, tsunami) and Biological (plants and animals as colonisers such as locusts; viral, fungal and bacterial diseases).

Earthquake zones of India: India is divided into five zones — very high, high, moderate, low and very low damage risk — based on analysis of more than 1,200 past earthquakes. The Himalayan belt, northeast, Kuchchh (Gujarat) and Kashmir Valley are most vulnerable.

Tsunami: high vertical sea waves (‘harbour waves’ / seismic sea waves) caused when earthquakes or volcanic eruptions move the sea floor abruptly. They are barely felt in the deep ocean but grow very tall (up to 15 m or more) in shallow coastal water.

Tropical cyclone: an intense low-pressure system confined between 30° N and 30° S, energised by latent heat from condensation of moisture. In India they form over the Bay of Bengal and Arabian Sea and bring storm surges to coasts.

Flood: inundation of land and settlements when surface run-off exceeds the carrying capacity of channels. Causes include heavy rainfall, storm surge, snowmelt, deforestation and encroachment of flood plains.

Drought: an extended shortage of water due to inadequate precipitation, high evaporation and over-use. Types: meteorological, agricultural (soil moisture), hydrological and ecological.

Landslide: the rapid downslope sliding of large masses of bedrock and debris under gravity, controlled mainly by highly localised factors — geology, slope, land use and vegetation cover.

Disaster management: three stages — pre-disaster (data, vulnerability mapping, awareness, preparedness), during disaster (rescue, relief, evacuation, shelter) and post-disaster (rehabilitation, recovery, capacity-building). Backed by the Disaster Management Bill, 2005 and the National Institute of Disaster Management.

NCERT Exercise — Full Solutions

All questions below are reproduced verbatim from the NCERT textbook’s end-of-chapter Exercises section (the original sub-part numbering in Question 2 is retained as printed). Answers are original, written in exam-ready style.

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. Assam, along with West Bengal and Bihar, ranks among the most flood-prone states of India because the Brahmaputra and its tributaries overflow almost every monsoon. Of the options, Assam experiences the most frequent and severe floods.

(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. The Malpa landslide of August 1998 occurred in the Pithoragarh district of Uttaranchal (now Uttarakhand), where a massive rock fall buried the village of Malpa and killed about 220 people, including Kailash–Mansarovar pilgrims.

(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. Tamil Nadu lies in the path of the retreating (north-east) monsoon and therefore receives most of its rain — and flooding — during the winter months of November to January, unlike the rest of India.

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

ANSWER (b) Brahmaputra. Majuli, in Assam, is the largest riverine (inhabited) island in the world and is situated in the river Brahmaputra. It is famous for good paddy crops after the fertile silt deposited by the annual floods.

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

ANSWER (a) Atmospheric. In the classification of natural disasters (Table 6.1), blizzards are listed under Atmospheric disasters, along with thunderstorms, lightning, tornadoes, tropical cyclones, drought and hailstorms.

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

(i) When can a hazard become a disaster?

ANSWER A natural hazard becomes a disaster when it actually strikes an area — especially one of high population density — and the magnitude of death, destruction and damage it causes is very high, disrupting life beyond the community’s coping capacity.

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

ANSWER The Indian plate moves northward about one centimetre a year and is obstructed by the Eurasian plate. The two plates remain locked, accumulating stress that is suddenly released along the Himalayan arch, causing frequent earthquakes there and in the northeast.

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

ANSWER The basic requirements are: a large and continuous supply of warm, moist air (releasing latent heat); a strong Coriolis force; unstable conditions through the troposphere creating local disturbances; and the absence of a strong vertical wind wedge.

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

ANSWER Eastern India (Assam, West Bengal, Bihar) suffers recurrent monsoon river floods almost every year from the overflowing Brahmaputra and Ganga systems, while western India (Rajasthan, Gujarat, Haryana) faces sudden flash floods caused by erratic rainfall and blocked channels.

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

ANSWER Central and western India (Rajasthan, Gujarat, interior Maharashtra and Madhya Pradesh) receive low and highly variable monsoon rainfall, lie in rain-shadow or arid zones, and have high evaporation, so the large-scale unpredictability of the monsoon makes droughts frequent and severe.

3. 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.

ANSWER Landslide-prone regions: India is divided into vulnerability zones. The Very High Vulnerability Zone includes the young, unstable Himalayas, the Andaman and Nicobar Islands, the high-rainfall, steep-sloped Western Ghats and Nilgiris, and the north-eastern regions. The High Vulnerability Zone covers all Himalayan states and the northeast except the plains of Assam. The Moderate to Low Zone includes the Trans-Himalayan Ladakh and Spiti, the Aravalis and rain-shadow areas; mining-related slides occur in Jharkhand, Odisha and the Deccan. Mitigation measures: adopt area-specific solutions — restrict construction of roads, dams and large settlements in high-vulnerability zones; limit agriculture to valleys and moderate slopes; promote large-scale afforestation; build bunds to reduce water flow; and encourage terrace farming in the north-eastern hills where shifting (jhum) cultivation is practised.

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

ANSWER Vulnerability is the degree to which a population, region or system is exposed and susceptible to the damaging effects of a hazard — the likelihood of suffering loss of life and property when a disaster strikes, due to physical, social and economic conditions. Drought vulnerability zones: (1) Extreme drought-affected areas — west of the Aravalis in Rajasthan (Marusthali), and the Kachchh region of Gujarat (districts like Jaisalmer and Barmer get less than 90 mm rainfall). (2) Severe drought-prone areas — eastern Rajasthan, most of Madhya Pradesh, eastern Maharashtra, interior Andhra Pradesh, Karnataka Plateau, interior Tamil Nadu and parts of Jharkhand and Odisha. (3) Moderate drought-affected areas — northern Rajasthan, Haryana, southern Uttar Pradesh and interior Karnataka. Mitigation: provide safe drinking water, fodder and medicines; transfer river water from surplus to deficit areas and inter-link rivers; build reservoirs; use remote sensing to find groundwater; and promote rainwater harvesting and drought-resistant crops.

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

ANSWER Developmental activities become a cause of disasters when they are carried out in an unscientific manner in fragile or hazard-prone areas, increasing people’s vulnerability. Indiscriminate deforestation and unscientific land use trigger landslides and floods; construction of roads and dams on unstable Himalayan slopes destabilises them. Colonisation of river flood-plains and river-beds, and the growth of large cities and port-towns like Mumbai and Chennai along the coast for high land values, expose dense populations to floods, cyclones and tsunamis. Disturbing natural drainage channels and over-pumping groundwater further intensify the magnitude and gravity of disasters. Thus, when technological power lets humans intensify activity in delicate ecosystems without regard for natural balance, development itself accelerates disasters.

Extra Practice Questions

Short Answer Type Questions

Q1. Distinguish between a natural hazard and a natural disaster.

ANSWERA natural hazard is an element of the natural environment that has the potential to cause harm to people or property, such as a steep unstable slope or strong ocean current. A natural disaster is the actual sudden, large-scale destruction — widespread death and loss of property — that occurs when such forces strike with high magnitude.

Q2. Name the four categories of natural disasters with one example each.

ANSWERThe four categories are: Atmospheric (tropical cyclone), Terrestrial (earthquake), Aquatic (tsunami) and Biological (locust infestation). This classification helps deal promptly and scientifically with each type of disaster.

Q3. Why is a tsunami difficult to detect in the deep ocean?

ANSWERIn deep water a tsunami has a very long wavelength but limited wave-height, so it raises a ship only a metre or two and each rise and fall takes several minutes. Its impact is therefore small over the open ocean and grows large only when it enters shallow coastal water.

Q4. List the four types of drought.

ANSWERThe four types are: (i) Meteorological drought — prolonged inadequate, badly distributed rainfall; (ii) Agricultural (soil-moisture) drought — low soil moisture causing crop failure; (iii) Hydrological drought — water in lakes, reservoirs and aquifers falling below replenishment; and (iv) Ecological drought — loss of ecosystem productivity due to water shortage.

Q5. What is a storm surge?

ANSWERA storm surge is an abnormal rise in the sea level caused when a cyclone’s very high horizontal pressure-gradient and strong surface winds drive sea water across the coast, along with heavy downpour. It inundates settlements and farmland, damages crops and destroys structures.

Long Answer Type Questions

Q1. Describe the causes and consequences of floods in India and the steps taken to control them.

ANSWERCauses: Floods occur when surface run-off exceeds the carrying capacity of river channels and spills into low-lying flood-plains. Natural causes include high-intensity prolonged rainfall, storm surges, snowmelt and reduced infiltration. Human actions — indiscriminate deforestation, unscientific agriculture, disturbance of drainage channels and colonisation of flood-plains — intensify them. The National Flood Commission identified 40 million hectares as flood-prone. Consequences: floods destroy crops, damage roads, rails, bridges and settlements, render millions homeless, drown cattle and spread water-borne diseases like cholera and hepatitis; though they also deposit fertile silt (as on Majuli island). Control measures: build flood-protection embankments and dams, afforest catchments, discourage construction in upper reaches, remove encroachment from river channels, depopulate flood-plains and set up cyclone centres in coastal areas.

Q2. Explain the distribution of earthquake zones in India and suggest measures for earthquake hazard mitigation.

ANSWERDistribution: Based on more than 1,200 past earthquakes, India is divided into five zones — very high, high, moderate, low and very low damage risk. The Very High Damage Risk Zone covers the north-eastern states, the Indo-Nepal border near Darbhanga–Araria in Bihar, Uttarakhand, western Himachal Pradesh (around Dharamshala), the Kashmir Valley and Kuchchh (Gujarat). The High Damage Risk Zone includes the rest of Jammu & Kashmir, Ladakh, Himachal Pradesh, northern Punjab, eastern Haryana, Delhi, western Uttar Pradesh and northern Bihar. The remaining areas, especially the stable Deccan plateau, fall under moderate to very low risk. Mitigation: establish seismological monitoring centres (and use GPS to track plate movement); prepare and circulate vulnerability maps; modify building designs and discourage high-rise construction in vulnerable areas; and make earthquake-resistant designs and light building materials mandatory.

Q3. Discuss the three stages of disaster management and the role of the Government of India.

ANSWERSince natural disasters cannot be eliminated, the best option is mitigation and preparedness through three stages of disaster management. (i) Pre-disaster management involves generating data and information, preparing vulnerability zoning maps, spreading awareness, and undertaking disaster planning, preparedness and preventive measures in vulnerable areas. (ii) During disasters, rescue and relief operations — evacuation, construction of shelters and relief camps, and emergency supply of water, food, clothing and medical aid — are carried out. (iii) Post-disaster operations focus on rehabilitation and recovery of victims and on capacity-building to cope with future disasters. These measures are vital for India, where about two-thirds of the area and population are vulnerable to disasters. The Government of India has introduced the Disaster Management Bill, 2005 and set up the National Institute of Disaster Management as positive steps in this direction.

MCQs & Assertion–Reason

1. According to the chapter, an event is classed as a disaster when:

(a) it occurs in nature    (b) the magnitude of destruction and damage caused by it is very high    (c) it is predictable    (d) it occurs only in deserts

2. The most unpredictable and highly destructive of all natural disasters is:

(a) flood    (b) drought    (c) earthquake    (d) landslide

3. Tsunamis are also called:

(a) tidal bores    (b) shallow water waves    (c) deep water waves    (d) trade winds

4. Tropical cyclones are confined to the area lying between:

(a) 0° and 5° latitudes    (b) 30° N and 30° S latitudes    (c) 40° and 60° latitudes    (d) the two poles

5. The Rashtriya Barh Ayog (National Flood Commission) identified how much land as flood-prone in India?

(a) 4 million hectares    (b) 20 million hectares    (c) 40 million hectares    (d) 80 million hectares

6. An area with more than 30 per cent of its gross cropped area under irrigation is excluded from the category of:

(a) hydrological drought    (b) drought-prone area    (c) flood-prone area    (d) cyclone zone

7. The largest riverine island in the world, known for good paddy crops after annual floods, is:

(a) Sriharikota    (b) Majuli    (c) Sundarban    (d) Diu

8. Landslides are largely controlled by:

(a) global factors    (b) highly localised factors    (c) ocean currents    (d) the Coriolis force

9. In the December 2004 tsunami, the approximate number of people who lost their lives was:

(a) more than 30,000    (b) more than 100,000    (c) more than 300,000    (d) more than 1,000,000

10. The Yokohama Strategy and Plan of Action for a Safer World was adopted at the World Conference held in May 1994 at:

(a) Rio de Janeiro    (b) Yokohama, Japan    (c) Geneva    (d) New Delhi

Answer key: 1-(b), 2-(c), 3-(b), 4-(b), 5-(c), 6-(b), 7-(b), 8-(b), 9-(c), 10-(b).

For each Assertion–Reason question, choose: (A) Both true and the Reason correctly explains the Assertion; (B) Both true but the Reason is not the correct explanation; (C) Assertion true, Reason false; (D) Assertion false, Reason true.

A-R 1. Assertion: There are frequent earthquakes along the Himalayan arch.

Reason: The Indian plate moves northward and is obstructed by the Eurasian plate, building up stress that is suddenly released.

A-R 2. Assertion: A ship in the deep ocean is not much affected by a tsunami.

Reason: In deep water a tsunami has a very long wavelength and limited wave-height.

A-R 3. Assertion: Tropical cyclones do not form between 0° and 5° latitude.

Reason: The Coriolis force is absent near the equator, so the low pressure at the centre cannot be sustained.

A-R 4. Assertion: Floods make no useful contribution at all.

Reason: Floods deposit fertile silt over agricultural fields, giving good crops, as on Majuli island.

A-R 5. Assertion: It is difficult to monitor and predict landslides.

Reason: Landslides are controlled by highly localised factors, making information-gathering difficult and cost-intensive.

Answer key: 1-(A), 2-(A), 3-(A), 4-(D), 5-(A).

Exam Tips & Common Mistakes

How to score full marks in this chapter

Always begin by clearly distinguishing a hazard from a disaster — potential to harm versus actual large-scale destruction. Memorise the four-fold classification (atmospheric, terrestrial, aquatic, biological) from Table 6.1 and the five earthquake zones. For each disaster, structure your answer as causes → distribution in India → consequences → mitigation. Quote the chapter’s facts to gain marks — one cm/year plate movement, 40 million hectares flood-prone, more than 300,000 deaths in the 2004 tsunami, the Yokohama Strategy (1994), the Disaster Management Bill, 2005 and the National Institute of Disaster Management. For map-based questions, name the specific states and regions.

Common mistakes to avoid

  • Using hazard and disaster as the same thing — a hazard has the potential to harm; a disaster is the actual destruction.
  • Listing the four disaster categories wrongly — remember floods and tsunami are aquatic, earthquakes and landslides are terrestrial.
  • Confusing the four types of drought (meteorological, agricultural, hydrological, ecological).
  • Forgetting that Tamil Nadu floods in winter (retreating monsoon), unlike most of India.
  • Saying tsunamis are huge in the deep ocean — they grow tall only in shallow coastal water.
  • Writing more than the word limit (30 / 125 words) in the NCERT exercise — keep answers crisp and to the point.

Frequently Asked Questions

What is Chapter 6 of Class 11 Geography (India: Physical Environment) about?

Chapter 6, Natural Hazards and Disasters: Causes, Consequences and Management, distinguishes hazards from disasters, classifies natural disasters, and studies India’s major disasters — earthquakes, tsunamis, tropical cyclones, floods, droughts and landslides — with their causes, distribution, consequences, mitigation and the three stages of disaster management.

What is the difference between a natural hazard and a natural disaster?

A natural hazard is an element of the natural environment that has the potential to cause harm to people or property. A natural disaster is the actual sudden, large-scale destruction — widespread death and loss of property — that takes place when such forces strike with very high magnitude.

Which states of India are most prone to floods, droughts and earthquakes?

Floods are most frequent in Assam, West Bengal and Bihar; severe droughts affect Rajasthan, Gujarat, interior Maharashtra and Madhya Pradesh; and the highest earthquake risk lies in the north-eastern states, the Himalayan belt, the Kashmir Valley and Kuchchh in Gujarat.

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