Get notes, summary, questions and answers, MCQs, extras, and PDFs of Chapter 16 “Disasters-Their Impact on the Environment” which is part of NBSE Class 11 Environment Education. However, the notes should only be treated as references and changes should be made according to the needs of the students.
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Summary
The chapter discusses various types of disasters and their impact on the environment. Disasters are sudden events that cause significant harm to humans, animals, and plants. They can be natural, such as earthquakes, floods, droughts, and cyclones, or man-made, like industrial and technological accidents.
An earthquake is described as a sudden movement of the Earth’s surface, caused by the release of energy from within the Earth. It can cause buildings to collapse, roads to crack, and even trigger landslides. The damage from earthquakes is usually severe near the epicenter, where the quake is strongest.
Tsunamis, often caused by underwater earthquakes, are large sea waves that can travel long distances, causing widespread destruction when they reach land. The chapter mentions the 2004 tsunami that caused immense loss of life and property in many countries, including India.
Droughts occur when there is an extended period of low rainfall, leading to water shortages and damage to crops. This can cause food scarcity and economic difficulties, particularly in regions that depend heavily on agriculture.
Floods are another natural disaster that occurs when large areas of land are submerged in water due to heavy rainfall or other factors. Floods can destroy homes, crops, and infrastructure, and can lead to long-term environmental damage, including soil erosion and loss of fertile land.
Cyclones are intense storms that form over warm ocean waters. In India, they commonly occur in the Bay of Bengal and the Arabian Sea, causing heavy rainfall, strong winds, and flooding in coastal areas. Cyclones can uproot trees, damage buildings, and disrupt communication and transportation networks.
The chapter also discusses man-made disasters, such as the Bhopal Gas Tragedy, where the leakage of toxic gas caused thousands of deaths. These disasters often result from industrial accidents and can cause long-term environmental damage, including pollution and health problems for the affected population.
Textbook solutions
Multiple-Choice Questions
1. What is a drought?
(a) The shortage of water for a long period of time.
(b) A year without rainfall.
(c) A month without rain.
(d) A week without precipitation.
Answer: (a) The shortage of water for a long period of time.
2. Sudden descent of a mass of earth and rock down a slope under the force of gravity is called
(a) Scrub fire
(b) Earthquake
(c) Landslide
(d) Famine
Answer: (c) Landslide
3. Which gas leaked from Union Carbide of India Limited, on December 3, 1984 in Bhopal?
(a) Methyl carbide
(b) Hydrogen fluoride
(c) Butane
(d) Methyl Isocyanate
Answer: (d) Methyl Isocyanate
4. Who developed the procedure used to measure the intensity of an earthquake?
(a) Charles Richter
(b) Edward Sheridan
(c) James Hutton
(d) Art Smith
Answer: (a) Charles Richter
5. What does the word “tsunami” mean in Japanese?
(a) Tidal Wave
(b) Harbour Wave
(c) Killer Wave
(d) Century Wave
Answer: (b) Harbour Wave
Short Answer Questions
1. Define disaster.
Answer: A disaster is a sudden calamity that may cause displacement of a great number of people living or working in an area.
2. List a few major disasters that occurred in India.
Answer:
- Bhopal Gas Tragedy, 1984
- Gujarat Earthquake, 2001
- Indian Ocean Tsunami, 2004
- Uttarakhand Floods, 2013
3. What are three main effects of a disaster?
Answer:
- Damage to human life and property
- Economic destruction
- Deterioration in health and health services
4. What are the aggravating factors of a disaster?
Answer: Rapid rate of urbanisation, industrial expansion, agricultural development, population growth, and social development are continuously accelerating the frequency and magnitude of natural disasters in Third World countries.
5. What do you understand by a natural disaster?
Answer: Natural hazards literally mean those natural happenings, which are potentially dangerous to human beings, causing injury, loss of life and property, and disrupting social and economic life. Natural environmental hazards and disasters involve comparatively high-intensity processes and extreme events caused by both terrestrial and atmospheric processes.
6. What do you mean by a man-made disaster?
Answer: Most important man-made disasters are technological and industrial. Both of these occur as a result of misuse of technology, accidents, etc. These disasters are mostly attributed to human errors.
7. Define the following:
Answer:
(i) Earthquake: An earthquake is a major demonstration of the power of the tectonic forces caused by endogenic thermal conditions in the interior of the Earth.
(ii) Tsunami: Tsunami is a Japanese word meaning “harbour wave.” These are the waves which often affect distant shores, originate from undersea or coastal seismic activity, landslide, and volcanic eruptions.
(iii) Cyclone: Cyclone is an atmospheric condition, generally called a storm. It is an environmental hazard. Cyclones bring violent winds and torrential rains, devastating low-lying coastal areas.
(iv) Drought: Drought can be defined as a prolonged period of unusually dry weather in a region where some rain is expected.
8. Where and when did the last tsunami occur?
Answer: The last tsunami occurred on December 26, 2004, after an earthquake in Indonesia.
9. Which are the landslide-prone areas in India?
Answer: In India, landslides are very common in the mountainous region of the northern and north-eastern parts.
10. Define disaster as a global issue.
Answer: Because of the increasing frequency of disasters, (both natural and man-made) these countries are facing repeated set-backs to progress. Disaster can be a strong aggravating factor in the differences between wealthy nations and poor nations.
11. What do you understand by the term ‘Mitigation’?
Answer: Mitigation is the process to avoid, reduce or remedy significant adverse environmental effects caused by natural or man-made activities.
12. Differentiate between a typhoon and a hurricane.
Answer:
- Typhoon: Cyclones occurring in South-east Asia.
- Hurricane: Cyclones occurring in North America.
Long Answer Questions
1. Discuss disasters in a global perspective.
Answer: Most of the world’s worst disasters occur in tropical regions, where most of the developing countries are situated. Because of the increasing frequency of disasters, (both natural and man-made) these countries are facing repeated setbacks to progress. Disaster can be a strong aggravating factor in the differences between wealthy nations and poor nations. Unless disasters can be mitigated and managed to the optimum level, it will continue to have a debilitating effect in the future. The most significant global effort made in recent times to mitigate the effects of disasters was the launching of IDNDR programme by the United Nations (International Decade for Natural Disaster Reduction). Its major conference held in Yokohama (Japan) in May 1994 evolved a plan of action known as Yokohama Strategies. India is highly vulnerable to extremes due to high population density, poor infrastructure, low human development index, and minimal coping capacity.
2. How do floods cause a devastating effect on human beings?
Answer: Floods cause heavy flow of water and consequently lead to soil erosion. It causes many impacts on agriculture production, including water contamination, damage to crops, loss of livestock, increased susceptibility of livestock to diseases. Major floods have varied effects on river-flood plain ecosystems. Floods can have an adverse effect on trees if they are too long submerged. Flood is a natural phenomenon and is a response to rainfall, but it becomes a hazard when it causes colossal loss to human life and property. It is aggravated by human activities.
3. Briefly explain climatic disasters.
Answer: Climatic disasters are extreme weather conditions that cause significant damage to the environment, human life, and property. They include droughts, floods, cyclones, and heatwaves. These disasters are a result of complex atmospheric processes influenced by factors like global warming, deforestation, and industrial activities. Droughts lead to water shortages, soil degradation, and food scarcity. Floods result in widespread damage to infrastructure, contamination of water sources, and loss of crops. Cyclones cause massive destruction to coastal areas, uprooting trees, damaging buildings, and affecting human lives. Heatwaves can lead to severe health issues, water shortages, and increased mortality rates.
4. Describe how human activities act as a catalyst in natural disasters.
Answer: Human activities often exacerbate the impact of natural disasters. Deforestation, for instance, removes the natural barriers that protect against floods and landslides. Urbanization and the construction of buildings in vulnerable areas like floodplains and coastal zones increase the risk of disaster damage. Industrial activities contribute to global warming, which in turn leads to more frequent and severe climatic disasters like cyclones and heatwaves. In addition, improper agricultural practices can lead to soil erosion and desertification, worsening the effects of drought. The diversion of rivers and the construction of dams without proper environmental assessments can also lead to catastrophic flooding.
5. How does a tsunami occur?
Answer: Tsunamis, popularly called tidal waves, are the waves which often affect distant shores and originate from undersea or coastal seismic activity, landslide, and volcanic eruptions. Seawater is displaced into a violent motion and swells up, ultimately breaking over land, even over very long distances, having great destructive power. Tsunamis may travel hundreds of kilometers across the deep ocean, reaching speeds of about 725 to 800 km/h. It may become a towering wall of water 50 ft. high or more, capable of destroying entire coastal settlements. Earthquakes cause vertical and horizontal displacement of the earth’s surface. One destructive effect of earthquakes is the occurrence of tidal waves, properly called seismic sea waves, their Japanese name being Tsunami. This can destroy entire towns or cities along the coastline.
6. What is the after effect of drought?
Answer: Drought leads to acute shortage of water and food by creating difficult conditions to survive. It generally damages ecological systems and yields few offsetting benefits. It destroys the topsoil, causing severe desertification in the affected area. Drought also causes soil erosion, health problems, unemployment, and the death of human beings and animals. The impact of drought on the environment is significant, as it disrupts agricultural activities, reduces water supply, and causes loss of biodiversity. Prolonged drought conditions can lead to migration and displacement of people, further exacerbating social and economic issues in the affected regions.
7. Write in brief about the prevention and control of disasters.
Answer: The prevention and control of disasters involve several key measures, including:
- Training of Relief Workers: People engaged in relief work should be properly trained.
- Earthquake-Resistant Infrastructure: Multi-storeyed buildings must have earthquake-resistant infrastructure.
- Public Awareness: People must be aware of the Do’s and Don’ts during an earthquake and thereafter.
- Water Conservation: The main step to reduce drought is to conserve water through rainwater harvesting, canal irrigation, contour and improved agricultural methods.
- Drought-Resistant Crops: Drought-resistant crops should be sown.
- Land Use Changes: Land use patterns should also be changed.
- Monitoring Drought: Both private and government agencies should closely monitor drought and evaluate it.
- Flood Control: Floods may be controlled by proper embankment systems.
- Trained Flood Control Personnel: Flood control personnel should have an up-to-date database in the computers.
- Artificial Reservoirs: Artificial reservoirs should be constructed in flood-prone areas.
- Training of Relief Workers for Floods: Relief workers should be properly trained.
- Mass Plantation: Mass planting of trees helps to minimise floods.
- Cyclone Prediction: The weather department, with the help of satellites, can locate the path and place of cyclones. This early prediction can help people to evacuate low-lying areas which will be worst affected.
- Improved Vegetation Cover: Improved vegetation cover, plantation, building dykes, and embankments can help in controlling the effects of cyclones.
- Landslide Prevention: Cutting trees for establishing railway tracks and for making place for human habitat must be restricted. Proper building code should be maintained in hilly regions. Buildings must not be constructed on steep slopes. Strict enforcement of the existing rules must be made.
8. How do man-made disasters affect human life? Give examples.
Answer: Man-made disasters have significant impacts on human life. These include:
- Technological and Industrial Disasters: These occur as a result of misuse of technology, accidents, etc. For example, the Bhopal Gas Tragedy in India, where thousands of people suffered from suffocation due to the leakage of Methyl Isocyanate gas. This disaster led to the death of almost 2,000 people and caused injuries to many others.
- Chemical Leaks and Accidents: These cause air, water, and land pollution, which adversely affect the biotic community. Exposure to harmful chemicals can cause blindness, deafness, and nervous disorders in human beings, and may also cause cancer.
- Nuclear Hazards: Risks are associated with the transportation and disposal of nuclear wastes over long distances. The launching of nuclear-powered satellites exposes humans to large amounts of dangerous and hazardous material.
- Environmental Pollution: Chemical leaks and accidents cause pollution that affects the environment, leading to long-term health issues and damage to ecosystems.
9. Discuss the effect of disasters on the environment.
Answer: Disasters have a profound effect on the environment. The impacts vary depending on the type of disaster:
- Earthquakes: Earthquakes cause vertical and horizontal displacement of the Earth’s surface, leading to the destruction of buildings, roads, and other infrastructure. This can also result in landslides in hilly regions, causing further environmental damage. Additionally, earthquakes can destroy agricultural systems, leading to loss of harvest or livestock and destruction of irrigation systems.
- Droughts: Droughts lead to an acute shortage of water and food, causing damage to ecological systems and resulting in desertification, soil erosion, and health problems for humans and animals.
- Floods: Floods cause heavy soil erosion, damage to crops, loss of livestock, and contamination of water supplies. They can also destroy trees and damage ecosystems, particularly in river-floodplain systems.
- Cyclones: Cyclones cause damage to crops, animals, and human lives. They uproot trees, blow away improperly constructed buildings, and can carry viral infections, leading to epidemics.
- Landslides: Landslides destroy human habitats, block roads, bury buildings, and cause significant economic loss. They can also lead to contamination of water sources, changes in vegetation, and other agricultural impacts.
10. What are the mitigation techniques accepted at the global level?
Answer: The mitigation techniques accepted at the global level include:
- Disaster Preparedness: Countries are focusing on training people and relief workers for better preparedness in the event of a disaster.
- Building Codes: There is an emphasis on constructing earthquake-resistant buildings, especially in earthquake-prone areas.
- Water Conservation: In drought-prone regions, water conservation techniques such as rainwater harvesting and the use of drought-resistant crops are promoted.
- Flood Control Measures: Proper embankment systems, construction of artificial reservoirs, and mass tree plantations are encouraged to control floods.
- Cyclone Prediction and Preparedness: The use of satellites to predict cyclones and the evacuation of vulnerable areas are key measures to reduce the impact of cyclones.
- Environmental Protection: Protecting forests and reducing deforestation are global priorities to mitigate the impact of disasters like landslides and floods.
11. Discuss one of the global efforts made in recent times to mitigate the effects of disasters.
Answer: One of the significant global efforts made in recent times to mitigate the effects of disasters is the launching of the International Decade for Natural Disaster Reduction (IDNDR) by the United Nations. The IDNDR was aimed at promoting international cooperation in the field of disaster reduction and to encourage nations to reduce the loss of life, property damage, and social and economic disruption caused by natural disasters.
During this decade, a major conference was held in Yokohama, Japan, in May 1994, which evolved a plan of action known as the Yokohama Strategies. These strategies focused on the assessment of disaster risks, the development of disaster-resistant infrastructure, public awareness, and education. The Yokohama Strategies represent a global commitment to reducing the impact of natural disasters through coordinated international efforts and have served as a foundation for disaster risk reduction initiatives worldwide.
Think and Answer
You all know about the killer Tsunami of December, 2004. What is your opinion regarding the role of individuals to prevent such a Tsunami? Discuss it in regional and global perspective.
Answer: Preventing a tsunami itself is beyond human capability, as it is a natural disaster triggered by undersea seismic activity, such as earthquakes. However, individuals can play a significant role in mitigating the impact and improving preparedness to reduce the loss of life and property in the event of a tsunami.
Regional Perspective:
- Awareness and Education: Individuals can educate themselves and their communities about the warning signs of a tsunami and the appropriate actions to take when a tsunami warning is issued. This includes participating in drills and understanding evacuation routes.
- Community Involvement: People can get involved in local disaster preparedness programs, working with local authorities to ensure that proper warning systems are in place and that everyone in the community is aware of them.
- Building Resilience: Individuals can advocate for and support the construction of tsunami-resistant infrastructure in their communities, such as elevated buildings and sea walls.
Global Perspective:
- Global Collaboration: On a global scale, individuals can contribute to and support international efforts focused on disaster risk reduction, such as the UN’s initiatives. By staying informed and involved in global discussions about disaster preparedness, individuals can help push for better warning systems and preparedness strategies worldwide.
- Support for Vulnerable Regions: People in more stable regions can offer support—whether financial, educational, or technical—to regions more vulnerable to tsunamis. This can include donating to disaster relief organizations, supporting international aid, or participating in global awareness campaigns.
- Advocacy for Climate Action: While tsunamis themselves are not caused by climate change, the broader impact of climate change on sea levels and weather patterns can exacerbate the damage from such events. Individuals can play a role by advocating for climate action to reduce these risks globally.
Extras MCQs
1. What scale is used to measure the magnitude of an earthquake?
A. Richter Scale
B. Fujita Scale
C. Beaufort Scale
D. Mercalli Scale
Answer: A. Richter Scale
17. Which event is an example of a nuclear hazard?
A. Volcanic eruption
B. Tsunami
C. Transportation of nuclear waste
D. Earthquake
Answer: C. Transportation of nuclear waste
Extra Questions and Answers
1. What is a disaster?
Answer: A disaster is a sudden, adverse or unfortunate event that causes great damage to human beings, plants, and animals. Disasters occur rapidly, instantaneously, and indiscriminately, causing significant harm to society.
23. What steps can be taken to prevent and mitigate man-made disasters?
Answer: To prevent and mitigate man-made disasters, several steps can be taken. On an international level, the United Nations is committed to reducing the dangers associated with nuclear hazards, and various countries, including India, have implemented measures to avoid such disasters. International and national laws are being developed to regulate and control the risks associated with technological and industrial activities. Ensuring proper training for workers, maintaining strict safety standards, and enforcing regulations are crucial steps in preventing such disasters. Additionally, governments and industries must prioritize environmental safeguards, even in developing countries, to mitigate the risks associated with rapid industrialization and technological advancement.
Ron’e Dutta is a journalist, teacher, aspiring novelist, and blogger. He manages Online Free Notes and reads Victorian literature. His favourite book is Wuthering Heights by Emily Bronte and he hopes to travel the world. Get in touch with him by sending him a friend request.
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