Natural hazards - floods, coastal hazards, earthquakes, and volcanic activity, and mitigation - 1 | Geology Optional Notes for UPSC PDF Download

Introduction

• Hazards arise from the interactions of physical, biological, and social systems.
• India faces various natural disasters like earthquakes, floods, cyclones, and droughts.
• Environmental degradation intensifies vulnerability to natural disasters.
• Notable natural hazards in India include the Kashmir floods in 2014, Uttarakhand flash floods in 2013, Indian Ocean Tsunami in 2004, Bhuj earthquake in Gujarat in 2001, Odisha Super cyclone in 1999, and the Latur earthquake in Maharashtra in 1993.

Understanding Natural Hazards

• Planet Earth is a dynamic system with intricate internal and external processes.
• Internal processes like plate movements and volcanic activities are powered by radioactivity.
• External processes such as floods and hurricanes are energized by the sun.
• Natural hazards can trigger secondary disasters; for instance, earthquakes causing landslides and building destruction, leading to water contamination and diseases like cholera.

Definitions of Hazard and Disaster

• Natural Hazards

  • Definition: Natural hazards are events stemming from Earth processes within the lithosphere, hydrosphere, or atmosphere that pose a threat to life or property.
  • Example: The 1995 earthquake in Kobe, Japan resulted in 5000 deaths and a loss of 200 billion dollars, illustrating the destructive impact of natural hazards.
  • Impact of Human Activities: Human actions can influence the severity of a hazard.

• Hazard and Disaster Definitions

  • Hazard: Defined as elements in the environment that are harmful to humans and are caused by external forces. Hazards have the potential to cause harm to people, human activities, property, and the environment.
  • Disaster: Occurs when a hazard materializes, leading to significant consequences.

• Hazard Events

  • Definition: Physical parameters of hazards that cause harm to individuals and society.
  • Transformation to Hazards: Environmental events become hazards when they negatively impact society and the environment.
  • Example: Volcanic eruptions, while often not harmful to humans, can pose risks in populated areas, turning them into hazardous events.

• Natural Disasters

  • Definition: Hazard events resulting in a significant number of fatalities and extensive property damage are classified as natural disasters.
  • Importance of Understanding: Studying natural hazards aids in prediction and preparation for potential calamities.

Dimensions of Hazard

• In assessing hazards, it's crucial to consider their magnitude, frequency, and intensity at the impact point.
• Factors like climate, geology, vegetation, population, and land use also play significant roles.
• Many hazards have return periods, indicating how often an event of a specific magnitude and intensity might happen.
• For instance, terms like "five-year floods" or "fifty-year floods" give an idea of recurrence frequency.

Classification of Natural Hazards

• Natural hazards are categorized into geological, hydrological, meteorological, and biological hazards.

Geological Hazards

• Geological hazards stem from earth processes like earthquakes, volcanic eruptions, landslides, and subsidence.
• Earthquakes, for instance, release immense energy rapidly, leading to significant loss of life and property.

Hydrological Hazards

• Hydrological hazards are triggered by water-related events such as floods, droughts, mudslides, and tsunamis.
• Floods, being frequent, cause substantial damage to both life and property.

Meteorological Hazards

• Meteorological hazards arise from weather processes like cyclones, hurricanes, tornadoes, droughts, and thunderstorms.
• These hazards can lead to various detrimental effects such as heavy rain, flooding, and heatwaves.

Natural hazards, especially when catastrophic, can have devastating consequences affecting large populations.

Biological Hazards

• Biological hazards are caused by biological agents, such as viruses and bacteria.
• They can lead to disease outbreaks like the bubonic plague in the 1300s and the 1918 Spanish flu pandemic.
• An epidemic occurs when an illness affects a large number of people, often due to poor environmental conditions.
• Epidemics can follow disasters, leading to mass illnesses and deaths.
• Vulnerable populations include those who are malnourished, living in unhygienic conditions, and lacking access to healthcare.
• Examples of biological hazards are Dengue, Avian flu, Swine flu, Cholera, Chikungunya, and Bubonic plague.

Secondary Hazards

• Secondary hazards are consequences of primary hazards like earthquakes.
• Examples of secondary hazards include dam failures, building collapses, ruptured power and water lines, landslides, and tsunamis resulting from earthquakes.

Natural Hazards Overview

• Chronic hazards are hazards that accumulate over time due to continuous conditions like pollution and toxic contamination.

Classification of Natural Hazards

• Natural hazards can be categorized into rapid onset hazards and slow onset hazards.
• Rapid onset hazards include events like volcanic eruptions, earthquakes, floods, and severe thunderstorms that occur suddenly.
• Slow onset hazards, on the other hand, comprise phenomena such as droughts and disease epidemics that develop gradually over years.
• The speed at which a hazard occurs is a crucial factor in its classification.

Factors Influencing Hazards

• Spatial dispersion refers to how a hazard is spread across a geographic area.
• Temporal spacing relates to the timing and seasonality of hazard events.
• Hazard scape describes the landscape of various hazards affecting people, their environments, and technology at different spatial levels.
• Each hazard has unique spatial and temporal characteristics that influence its impact.

Natural Hazards Impact on India

• India has faced numerous natural hazards leading to significant loss of life and property.
• The 1990s marked the International Decade for Natural Disaster Reduction, highlighting the global focus on mitigating such disasters.

Man-made Hazards

• Man-made hazards, also known as technological hazards, encompass exposure to dangerous substances such as radon, mercury, asbestos fibers, acid rain, or contaminated waters.
• Chemical disasters are a significant component of man-made hazards. These disasters involve uncontrolled events like fires, explosions, or toxic substance releases, leading to loss of life, injuries, and extensive environmental and economic harm.
• One notable example of a chemical disaster is the Bhopal gas tragedy in 1984, which had catastrophic consequences.

Chemical Disasters

• Industrial disasters, a subset of man-made disasters, surged post-World War II due to the chemical industry's rapid growth.
• These disasters involve unregulated incidents like fires, explosions, or toxic releases, causing harm to people and significant environmental and economic damage.

Slow-Onset Disasters

• Slow-onset disasters occur when humans are exposed to toxic substances from man-made pollution activities.
• An illustrative case is the "Minamata disease," where a factory discharged effluent with inorganic mercury into Minamata Bay, leading to mercury poisoning in humans who consumed contaminated fish.
• The victims exhibited symptoms like polyneuritis, cerebellar ataxia, and cortical blindness due to mercury poisoning.

Fires

• Fires pose a threat to human life, property, and wildlife while causing environmental pollution.
• Man-made causes of fires include activities like burning matchsticks, cooking accidents with LPG gas or kerosene, electrical wiring issues, forest fires, and transportation of flammable materials.

Effects of Natural Hazards

• Primary effects occur directly due to the hazard itself. For instance, a building collapsing during an earthquake or landslide.
• Secondary effects are caused by the primary event. Examples include fires from volcanic eruptions and disruptions in power and water services due to earthquakes.
• Tertiary effects are long-term consequences triggered by primary events. For example, crop failures due to volcanic eruptions and habitat loss from severe floods.

Natural Service Functions of Natural Hazards

• Natural hazards also play a crucial role in supporting ecosystems and human life.
• Volcanic activities contribute to the creation of the hydrosphere and atmosphere, essential for life on Earth.
• Floods and landslides replenish soil, enriching it with nutrients vital for plant growth.
• River floods deposit water and nutrients on floodplains, fostering nutrient-rich soils and diverse landscapes.
• Disturbances caused by natural processes like earthquakes and floods ensure water availability and fertile soils.

Understanding Vulnerability to Natural Hazards

• Proximity to a possible hazardous event: The closeness to a potential natural disaster greatly influences vulnerability. Areas near fault lines or coastlines face higher risks.
• Population density, construction styles, and building codes: High population density coupled with inadequate construction standards can increase vulnerability. Proper building regulations are crucial for resilience.
• Understanding and awareness of the nature of the hazard: Education and awareness about natural hazards are essential for preparedness and effective response to minimize damage.
• Early-warning systems, lines of communication, and emergency infrastructure: Access to timely warnings and well-established communication channels are critical for reducing vulnerability. Robust emergency infrastructure ensures swift response and recovery.

In general, developing nations often face higher vulnerability to natural hazards compared to developed countries due to factors like lack of education, poor infrastructure, and inadequate building codes.

Impact of Human Intervention on Natural Hazards

While humans cannot control natural phenomena, their actions can influence the outcomes of these events:

• Development and habitation of lands susceptible to hazards: Building settlements in high-risk areas like floodplains or unstable slopes increases vulnerability to disasters.
• Reduction of natural ecosystems' mitigating effects: Human activities that harm natural ecosystems, such as deforestation, can heighten vulnerability to hazards by removing natural protective barriers.

For instance, when people clear forests on landslide-prone slopes for agriculture, they enhance the likelihood of disastrous landslides. Similarly, occupying volcanic regions for farming can expose individuals to dangers during eruptions.

Assessing Hazards

• Definition of Hazard Assessment: Hazard Assessment, also known as Hazard Evaluation or Hazard Analysis as per UNDRO (1991), involves estimating the likelihood of a disaster of a specific magnitude occurring within a defined timeframe.
• Variability in Hazard Occurrence: The probability of a hazard taking place varies from one location to another.
• Utilization of Mapping: Employing mapping techniques to comprehend natural hazard data enhances communication among individuals involved in hazard management and facilitates collaboration between planners and decision-makers.
• Components of Hazard Assessment: The hazard assessment process encompasses:
  • Reviewing past hazardous events, including their nature and frequency.
  • Evaluating the social and economic impacts of previous hazardous occurrences.
  • Analyzing the vulnerability of specific locations, buildings, and infrastructure to hazards.
• Decision-Making and Mitigation: Data collected during hazard assessment is shared with relevant authorities, scientists, and policymakers to assist in making informed decisions and implementing mitigation measures in preparation for potential disasters.

For instance, when considering hazard assessment in a flood-prone area, the process would involve studying historical flood patterns, assessing the impact on communities and infrastructure, and identifying vulnerable areas for targeted intervention. This information is crucial for authorities to develop effective disaster response plans and minimize risks associated with future flooding incidents.

Summary: National and International Attention - Hazard Mitigation

• The 1990s were marked as the International Decade for Natural Disaster Reduction (IDNDR) by the United Nations, aiming to minimize the impacts of natural disasters on life, property, and socio-economic aspects.
• Under the IDNDR, National Platforms were recommended for UN-member states to adapt disaster risk reduction goals locally, implement policies, and raise awareness about disaster risk reduction at national levels.
• The International Strategy for Disaster Reduction (ISDR) builds on the initiatives of the IDNDR, fostering cooperation and developing new mechanisms to secure commitments from policymakers.
• The primary objective is to decrease human, social, economic, and environmental losses resulting from natural hazards.
• The Yokohama conference in 1994 emphasized the necessity of integrating disaster prevention, mitigation, preparedness, and relief into sustainable development policies at national and international levels.
• Disaster prevention, mitigation, and preparedness are deemed critical components of integrated disaster management, as highlighted by the Yokohama conference.
• India, for instance, has integrated mitigation and prevention into its development strategy, with the Tenth Five Year Plan emphasizing the importance of disaster management for sustainable development.
• Hazards are inevitable in life, and assessing hazards is crucial for devising effective strategies. Policies significantly influence the impact of natural disasters, emergency management, land use planning, and construction standards.