Unit5 - Subjective Questions

Definition: A flood is an overflow of water that submerges land that is usually dry. It is a natural hydrometeorological event but can be exacerbated by human activities.

Causes of Floods:

• Natural Causes: Heavy rainfall, melting of snow/ice, storm surges in coastal areas, and siltation of riverbeds.
• Anthropogenic Causes: Deforestation (reduces water absorption), improper urban planning (blocking drainage), and dam failures.

Mitigation Measures:

1. Structural Measures:
   • Construction of embankments and flood walls.
   • Building dams and reservoirs to store excess water.
   • Channel improvement to increase water carrying capacity.
2. Non-Structural Measures:
   • Flood Plain Zoning: Restricting construction in high-risk zones.
   • Flood Forecasting and Warning Systems: Early alerts to evacuate people.
   • Afforestation: Planting trees to increase soil retention and reduce runoff.

Drought is a prolonged period of abnormally low rainfall. It is classified into three main types based on its impact:

1. Meteorological Drought:

   • Definition: It occurs when there is a significant decrease in rainfall compared to the normal average over a specific period.
   • Indicator: Defined purely by precipitation deficiency (e.g., rainfall less than 75% of normal).

2. Hydrological Drought:

   • Definition: It refers to the depletion of surface and subsurface water resources.
   • Impact: Marked by low water levels in streams, lakes, and reservoirs, often lagging behind meteorological drought.

3. Agricultural Drought:

   • Definition: It occurs when soil moisture is insufficient to support healthy crop growth.
   • Impact: Leads to crop failure and food scarcity, heavily depending on the timing of rainfall relative to the crop cycle.

Formation of Cyclones:
Cyclones are large scale air masses that rotate around a strong center of low atmospheric pressure. They form over warm ocean waters (surface temperature above ). The warm, moist air rises, creating a low-pressure zone. Surrounding high-pressure air rushes in, spirals upwards due to the Coriolis force, and condenses to form clouds, releasing latent heat that fuels the storm.

Safety Measures:

• Before:
  • Check houses for structural repairs.
  • Store dry food, water, and medicines.
  • Keep mobile phones charged and listen to radio warnings.
• During:
  • Stay indoors and switch off electrical mains.
  • If outdoors, seek a safe shelter away from trees and poles.
  • Do not venture into the sea.

Earthquake: An earthquake is the shaking of the Earth's surface resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves.

Seismic Waves:

• Body Waves: Travel through the interior of the Earth. Includes P-waves (Primary, longitudinal) and S-waves (Secondary, transverse).
• Surface Waves: Travel along the Earth's surface (e.g., Love waves, Rayleigh waves) and cause the most destruction.

Measurement:

• Richter Scale: Measures the magnitude (energy released). It is logarithmic; an increase of 1 indicates a 10-fold increase in amplitude and approx $31.6$ times more energy.
• Modified Mercalli Scale: Measures the intensity (observed effects/damage) at a specific location.

Definition: A landslide is the movement of a mass of rock, debris, or earth down a slope.

Causes:

• Physical: Gravity acting on over-steepened slopes, prolonged rainfall saturating the soil, and earthquakes.
• Human: Deforestation, mining, and road construction in hilly terrain which destabilizes slopes.

Effects:

• Blocking of roads and disruption of transport.
• Damming of rivers leading to flash floods.
• Loss of life and property in settlements at the foothills.

Prevention:

• Afforestation: Roots bind the soil.
• Retaining Walls: Concrete walls to support slopes.
• Drainage Control: Diverting surface water to prevent soil saturation.
• Hazard Mapping: Identifying prone areas to avoid construction.

Definition: An avalanche is a rapid flow of snow down a sloping surface.

Trigger Factors:

• Snowpack Structure: Weak layers within the snowpack cannot support the weight of the fresh snow on top.
• Weather: Heavy snowfall, wind depositing snow (wind loading), and rapid temperature changes.
• Terrain: Slopes between and are most prone.
• Triggers: Loud noises, vibrations, skiers/hikers, or new snowfall.

Safety Protocols:

• Monitor avalanche forecasts before travel.
• Carry safety gear: Transceivers, probes, and shovels.
• Avoid traveling alone in high-risk zones.
• If caught: Try to swim to the surface and create an air pocket in front of the face before the snow sets like concrete.

Volcanic eruptions involve the expulsion of lava, tephra (ash), and gases from a volcanic vent.

Human Impacts:

• Loss of Life: Direct impact from lava flows, pyroclastic flows (fast-moving hot gas and rock), and lahars (mudflows).
• Displacement: Evacuation of populations leads to refugee crises.
• Health Issues: Ash causes respiratory problems (silicosis, asthma).

Environmental Impacts:

• Air Pollution: Release of sulfur dioxide () which can lead to acid rain and stratospheric aerosols causing temporary global cooling.
• Climate Change: Greenhouse gases () are released, though less than anthropogenic sources.
• Habitat Destruction: Lava burns forests, and ash blankets vegetation, but eventually, volcanic soil becomes highly fertile for agriculture.

Definition: A nuclear disaster involves the accidental release of radioactive material into the environment, causing significant harm to people and the ecosystem.

Hazards:

1. Ionizing Radiation: Causes immediate radiation sickness (nausea, skin burns) and long-term genetic mutations or cancers (leukemia, thyroid cancer).
2. Contamination: Radioactive isotopes (like Cesium-137, Iodine-131) contaminate soil, water, and the food chain for decades (bioaccumulation).
3. Psychological/Social: Mass evacuation and fear of invisible danger.

Example: Chernobyl (1986): A reactor explosion in Ukraine released massive radiation across Europe. It led to an exclusion zone, thousands of thyroid cancer cases, and long-term ecological damage.

Causes of Chemical Disasters:

• Human error (negligence in operation).
• Technical failure (corrosion, valve failure).
• Improper storage of hazardous chemicals.
• Transportation accidents involving tankers.

Bhopal Gas Tragedy (1984):

• Incident: Leakage of Methyl Isocyanate (MIC) gas from the Union Carbide plant.
• Cause: Water entered the tank containing MIC, causing an exothermic reaction and pressure buildup.
• Impact: Thousands died instantly; long-term respiratory and genetic issues persist.

Management:

• Strict Regulations: Compliance with laws like the Manufacture, Storage and Import of Hazardous Chemical Rules.
• Siting Policies: Industrial zones must be far from residential areas.
• On-site Emergency Plans: Automated shut-off systems and alarms.

Definition: Biological disasters involve the devastating effects caused by the spread of disease-causing organisms (bacteria, viruses, toxins) impacting humans, animals, or plants. They can be natural (epidemics/pandemics) or manmade (bioterrorism).

Difference:

• Natural Pandemics: Arise naturally via mutation or zoonotic transfer (e.g., COVID-19, Influenza).
• Manmade/Bioterrorism: Deliberate release of pathogens (e.g., Anthrax attacks) to cause panic and death.

Containment Strategies:

• Surveillance: Early detection of disease outbreaks.
• Quarantine/Isolation: Separating infected individuals.
• Vaccination: Rapid immunization programs.
• Sanitation: Disinfection of affected areas and vector control.

Transport Accidents: Major accidents involving road, rail, air, or water transport that result in mass casualties or environmental damage.

Environmental Threats (Hazardous Materials):

• Oil Spills: Accidents involving oil tankers (ships) cause massive marine pollution, killing aquatic life, coating birds' feathers, and disrupting coastal ecosystems.
• Chemical Spillage: Road or rail tankers overturning can release toxic chemicals into the soil or nearby water bodies (groundwater contamination).
• Nuclear Transport: Accidents during the transport of radioactive waste pose severe radiation risks.
• Air Pollution: Fire and explosions release toxic fumes (dioxins, furans) into the atmosphere.

Definitions:

• Hazard: A dangerous phenomenon, substance, human activity, or condition that may cause loss of life, injury, or environmental damage (e.g., an earthquake in a desert).
• Vulnerability: The characteristics of a community or system that make it susceptible to the damaging effects of a hazard (e.g., poor building quality).
• Disaster: A serious disruption of the functioning of a community involving widespread losses that exceed the ability of the affected community to cope using its own resources.

Risk Equation:

• Risk increases with higher hazard intensity and vulnerability.
• Risk decreases if the Capacity (coping mechanisms/preparedness) of the community is high.

The Disaster Management Cycle is a continuous process of planning and action.

1. Pre-Disaster Phase (Risk Reduction):

• Prevention/Mitigation: Measures to eliminate or reduce the impact (e.g., building dams, earthquake-resistant codes).
• Preparedness: Getting ready to respond (e.g., stockpiling food, mock drills, early warning systems).

2. During Disaster:

• Response: Immediate actions to save lives (e.g., search and rescue, first aid, evacuation).

3. Post-Disaster Phase (Recovery):

• Rehabilitation: Restoring basic services (water, power) and temporary shelter.
• Reconstruction: Long-term rebuilding of infrastructure and livelihoods, ideally 'Building Back Better' to reduce future vulnerability.

India follows a tiered structure for disaster management, established by the Disaster Management Act, 2005.

1. National Level (NDMA):

• National Disaster Management Authority.
• Head: Prime Minister.
• Role: Apex body that lays down policies, plans, and guidelines for disaster management to ensure a timely and effective response.

2. State Level (SDMA):

• State Disaster Management Authority.
• Head: Chief Minister.
• Role: Implements national plans and creates state-specific disaster management policies.

3. District Level (DDMA):

• District Disaster Management Authority.
• Head: District Magistrate/Collector.
• Role: The actual execution body responsible for planning, coordinating, and implementing mitigation and response measures at the ground level.

Various government bodies work in tandem during a disaster:

• National Disaster Response Force (NDRF): A specialized force constituted for the purpose of specialist response to a threatening disaster situation or disaster. They are trained for chemical, biological, radiological, and nuclear (CBRN) emergencies and collapse structure search and rescue.
• Armed Forces (Army, Navy, Air Force): Called upon when civil administration is overwhelmed. They assist in aerial surveys, dropping food packets, heavy-lift transport, and evacuation in inaccessible areas.
• Police & Fire Services: First responders responsible for maintaining law and order, traffic control during evacuation, and immediate fire/rescue operations.
• IMD (India Meteorological Department): Provides forecasting and early warning for cyclones, floods, etc.

NGOs play a critical gap-filling role in disaster management due to their flexibility and grassroots connect.

• Immediate Relief: Distribution of food, water, clothes, and medicines immediately after a disaster, often faster than government bureaucracy.
• Specialized Care: Providing psychological counseling (trauma care) to victims.
• Rehabilitation: Helping build low-cost housing and restoring livelihoods (e.g., providing fishing nets or seeds).
• Advocacy & Awareness: Educating communities about disaster preparedness and hygiene to prevent epidemics.
• Inclusivity: Ensuring marginalized groups (women, disabled, elderly) receive aid, who might otherwise be overlooked.

CBOs are local groups (e.g., youth clubs, women's self-help groups, Resident Welfare Associations) operating within a community.

Significance:

• First Responders: The community is always the first to respond before external help arrives.
• Local Knowledge: They possess indigenous knowledge of the terrain, safe escape routes, and the most vulnerable households.
• Trust: They enjoy higher trust levels among locals compared to outsiders, aiding in crowd control and orderly evacuation.
• Resource Mobilization: Can quickly mobilize local resources (boats, vehicles, shelter) for rescue.
• Sustainability: They remain after relief agencies leave, ensuring long-term maintenance of reconstruction efforts.

Positive Role (Force Multiplier):

• Early Warning: Disseminating weather alerts and evacuation orders rapidly to millions.
• Information Exchange: Informing the public about helpline numbers, relief camp locations, and safety do's/don'ts.
• Accountability: Highlighting gaps in government relief efforts, putting pressure on authorities to act.

Negative Role (Double-edged Sword):

• Panic Mongering: Sensationalizing news or spreading unverified rumors can lead to panic and stampedes.
• Privacy Violation: Intrusive coverage of victims' grief for TRP ratings.
• Distraction: Focusing only on high-profile areas, ignoring remote villages that might be worse hit.

Natural Disasters:

• Origin: Caused by natural forces of the earth/nature.
• Predictability: Some can be predicted (cyclones), others cannot (earthquakes).
• Prevention: Cannot be prevented, but impacts can be mitigated.
• Examples: Floods, Tsunamis, Volcanic eruptions.

Manmade Disasters:

• Origin: Caused by human negligence, error, or intent.
• Predictability: Often occur suddenly due to system failure.
• Prevention: Highly preventable through strict safety protocols and regulations.
• Examples: Nuclear leaks (Chernobyl), Chemical spills (Bhopal), Bioterrorism.

Intersection: Often natural disasters trigger manmade ones (e.g., the Fukushima nuclear disaster was triggered by a natural tsunami), known as Natech disasters.

Mitigation aims to reduce the loss of life and property.

Structural Mitigation (Physical Construction):

• Retrofitting: Strengthening existing buildings to withstand ground shaking.
• Base Isolation: Using flexible pads (isolators) between the building foundation and the ground to absorb seismic energy.
• Shear Walls: Constructing reinforced concrete walls that resist lateral forces.
• Lightweight Materials: Using wood or steel instead of heavy masonry to reduce the collapse force.

Non-Structural Mitigation (Policies/Education):

• Building Codes: Enforcing strict adherence to seismic codes (e.g., IS 1893 in India).
• Land Use Planning: Prohibiting high-rise construction in high seismic zones.
• Public Awareness: Conducting drills ('Drop, Cover, and Hold On').
• Securing Interiors: Anchoring heavy furniture and cabinets to walls to prevent falling injuries.