Chapter – 6

Natural Hazards and Disasters

In this post we have given the detailed notes of Class 11 Geography Book 2 Chapter 6 (Natural Hazards and Disasters) in English. These notes are useful for the students who are going to appear in Class 11 board exams.

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Chapter 6: Natural Hazards and Disasters

Introduction

• Change as the law of nature: The natural world is in a constant state of flux, with changes occurring both gradually and abruptly.  
• Types of changes: Gradual changes include the evolution of landforms and organisms, while sudden changes encompass events like volcanic eruptions, tsunamis, earthquakes, and lightning.  
• Scale of changes: Changes can be localized, such as hailstorms and tornadoes, or global, such as global warming and ozone layer depletion.  
• Perspectives on change: From nature’s perspective, changes are value-neutral, neither good nor bad. However, from a human perspective, changes can be desirable (e.g., change of seasons) or undesirable (e.g., earthquakes, floods).  

Understanding Disasters

• Definition of disaster: A disaster is an unexpected and undesirable event, primarily caused by forces beyond human control, that occurs quickly and causes or threatens significant disruption of life, property, and society, including death and injury to a large number of people.  
• Natural disasters: These are caused by natural forces and include events like earthquakes, tsunamis, cyclones, floods, droughts, and landslides.  
• Human-made disasters: These are caused by human actions, either directly (e.g., Bhopal Gas Tragedy, Chernobyl) or indirectly (e.g., deforestation leading to landslides).  

Natural Hazards vs. Natural Disasters

• Natural hazards: These are elements or circumstances in the natural environment that have the potential to cause harm to people or property, such as steep slopes, unstable geological features, or extreme climatic conditions.  
• Natural disasters: These are sudden, large-scale events that cause widespread death, property loss, and social disruption, exceeding the normal coping capacity of the affected community.  

Changing Perspectives on Disasters

• Traditional view: Disasters were seen as solely the result of natural forces, with humans as helpless victims.  
• Modern view: Recognizes the role of human activities in causing and exacerbating disasters.  
• Increased vulnerability: Human activities, such as colonizing floodplains and coastal areas, have increased our vulnerability to disasters.  

Yokohama Strategy and International Decade for Natural Disaster Reduction (IDNDR)

• Yokohama Strategy: A guide to mitigate losses due to natural disasters, adopted at the World Conference on Natural Disaster Reduction in 1994.  
• Key principles:
  • Each country is responsible for protecting its citizens.  
  • Priority attention should be given to developing countries.  
  • National capacities and capabilities should be strengthened.  
  • International cooperation is essential.  
• IDNDR: The decade 1990-2000 was declared as the International Decade for Natural Disaster Reduction.  

Classification of Natural Disasters

• Four main categories:
  • Atmospheric: e.g., Tropical Cyclones, Tornadoes, Heat Waves  
  • Aquatic: e.g., Floods, Tsunami, Storm Surges  
  • Terrestrial: e.g., Earthquakes, Volcanic Eruptions, Landslides  
  • Biological: e.g., Epidemics, Pandemics  

Natural Disasters and Hazards in India

• India’s vulnerability: Due to its diverse physical and socio-cultural environment, India is highly vulnerable to various natural disasters.  
• Major natural disasters in India

a) Earthquakes:

• Causes: Primarily caused by the movement of the Indian tectonic plate against the Eurasian plate, leading to energy accumulation and release along the Himalayan arch.  
• High-risk areas: North-east states, areas along the Indo-Nepal border, Uttarakhand, Himachal Pradesh, Kashmir Valley, and Kuchchh (Gujarat).  
• Consequences:
  • Damage and destruction of infrastructure, settlements, and communication networks.  
  • Loss of life and property.  
  • Disruption of social and economic activities.  
  • Environmental impacts like landslides, floods, and changes in river courses.  
• Mitigation measures:
  • Earthquake monitoring and early warning systems.  
  • Vulnerability mapping and public awareness campaigns.  
  • Earthquake-resistant building designs and land-use planning.  

b) Tsunami:

• Causes: Generated by earthquakes or volcanic eruptions under the sea, causing sudden displacement of ocean water.  
• Characteristics:
  • Long wavelength and low wave height in deep water.  
  • Increased wave height and destructive power near the coast.  
• Consequences:
  • Inundation of coastal areas, causing widespread damage to infrastructure and settlements.  
  • Significant loss of life and property.  
• Mitigation measures:
  • International cooperation for early warning systems.  
  • Coastal zone management and evacuation plans.  

c) Tropical Cyclones:

• Formation:
  • Requires a large, continuous supply of warm, moist air.  
  • Strong Coriolis force prevents the filling of low pressure at the center.  
  • Unstable atmospheric conditions and absence of strong vertical wind wedge.  
• Distribution in India:
  • Originate in the Bay of Bengal and the Arabian Sea.  
  • Mostly develop during the monsoon season (October-November).  
• Consequences:
  • Storm surges: Abnormal rise in sea level, inundating coastal areas.  
  • High-velocity winds: Cause damage to infrastructure, crops, and settlements.  
  • Heavy rainfall: Leads to flooding and landslides.  
• Mitigation measures:
  • Cyclone shelters and early warning systems.  
  • Coastal zone management and afforestation.  

d) Floods:

• Causes:
  • Excessive rainfall exceeding the carrying capacity of rivers and streams.  
  • Storm surges in coastal areas.  
  • Melting of ice and snow.  
  • Human activities like deforestation and encroachment on floodplains.  
• Flood-prone areas in India:
  • Assam, West Bengal, Bihar, and Eastern Uttar Pradesh.  
  • Coastal areas of Odisha, Andhra Pradesh, Tamil Nadu, and Gujarat.  
  • Punjab, Rajasthan, Northern Gujarat, and Haryana (flash floods).  
• Consequences:
  • Damage to crops, infrastructure, and human settlements.  
  • Loss of life and livestock.  
  • Spread of waterborne diseases.  
• Mitigation measures:
  • Construction of flood protection embankments and dams.  
  • Afforestation and watershed management.  
  • Removal of encroachment from river channels and floodplains.  

e) Droughts:

• Causes:
  • Inadequate rainfall and maldistribution over time and space.  
  • High evaporation rates and over-utilization of water resources.  
• Types of droughts:
  • Meteorological drought: Prolonged period of inadequate rainfall.  
  • Agricultural drought: Low soil moisture leading to crop failure.  
  • Hydrological drought: Water availability in storages falls below replenishment levels.  
  • Ecological drought: Failure of natural ecosystems due to water shortage.  
• Drought-prone areas in India:
  • Rajasthan, particularly the western part.  
  • Parts of Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Jharkhand, and Odisha.  
• Consequences:
  • Crop failure and food scarcity.  
  • Water scarcity and livestock deaths.  
  • Human migration and spread of diseases.  
• Mitigation measures:
  • Rainwater harvesting and water conservation.  
  • Inter-linking of rivers and construction of dams and reservoirs.  
  • Drought-resistant crops and sustainable agricultural practices.  

f) Landslides:

• Causes:
  • Unstable slopes and geological conditions.  
  • Heavy rainfall and seismic activity.  
  • Human activities like deforestation and construction.  
• Landslide-prone areas in India:
  • Himalayas, Andaman and Nicobar Islands, Western Ghats, Nilgiris, and Northeastern regions.  
  • Areas with mining activities and unstable land.  
• Consequences:
  • Roadblocks and disruption of transportation networks.  
  • Damage to settlements and infrastructure.  
  • Loss of life and property.  
• Mitigation measures:
  • Restricting construction and development in high-risk areas.  
  • Afforestation and soil conservation measures.  
  • Terrace farming and sustainable land-use practices.  

Disaster Management

• Importance: Disaster management is crucial for mitigating the impact of disasters and protecting lives and livelihoods.  
• Stages of disaster management:
  • Pre-disaster:
    • Hazard assessment and risk analysis.  
    • Vulnerability mapping and community awareness.  
    • Disaster planning and preparedness measures.  
  • During disaster:
    • Evacuation and search and rescue operations.  
    • Establishment of relief camps and provision of essential supplies.  
  • Post-disaster:
    • Rehabilitation and recovery of affected communities.  
    • Damage assessment and reconstruction efforts.  
    • Capacity building for future disaster preparedness.  

Disaster Management in India:

• Disaster Management Bill, 2005: Provides a legal framework for disaster management.  
• National Institute of Disaster Management: Conducts research, training, and capacity building for disaster management.  

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