Unit 5: Disaster management

CHE110 — Environmental Studies 11 min read

I. Orientation — principles of disaster management

Disaster management is the organized process of prevention, mitigation, preparedness, response, recovery, and reconstruction before, during, and after a hazardous event. Its central principle is to reduce risk by combining hazard information, vulnerability reduction, institutional coordination, and community participation.

Disaster: A serious disruption causing human, material, economic, or environmental losses beyond the affected community’s capacity to cope.
Hazard: A potentially damaging event, such as an earthquake, flood, epidemic, or industrial leak.
Risk: The expected possibility of loss, commonly understood as a function of hazard, exposure, and vulnerability.
Capacity: Available skills, institutions, infrastructure, resources, and social networks that reduce disaster impacts.
Disaster cycle: Mitigation and prevention precede an event; preparedness supports immediate action; response saves lives; recovery restores and improves livelihoods.
Core convention: Risk reduction should follow the principle “build back better,” replacing unsafe structures and practices rather than reproducing them.

II. Natural disasters — hazards from natural processes

A. Natural disasters

Natural disasters arise from geophysical, hydrological, meteorological, climatological, or biological processes that threaten people and ecosystems.

Main groups: Earthquakes and volcanoes are geophysical; floods and droughts are hydrological or climatological; epidemics may be biological.
Impact equation: Losses increase when a hazard affects densely populated, exposed, and vulnerable communities.
Risk reduction: Land-use planning, hazard mapping, early-warning systems, resilient construction, public education, and evacuation planning reduce consequences.
Human influence: Deforestation, unplanned urbanization, wetland destruction, and climate change can intensify natural hazards.

III. Water-related disasters — excess or shortage of water

A. Water-related disasters

Water-related disasters result from too much, too little, or contaminated water, and commonly affect settlements, agriculture, health, and infrastructure.

Types: Floods, flash floods, storm surges, droughts, glacial lake outbursts, and waterborne disease outbreaks.
Common impacts: Crop failure, drinking-water contamination, displacement, infrastructure damage, and increased diarrhoeal disease.
Management: Watershed conservation, drainage planning, water storage, wetland protection, drought-resistant crops, and reliable warnings are essential.

B. Floods and drought

Floods occur when water inundates normally dry land, while drought is a prolonged period of unusually low precipitation or water availability.

Flood causes: Intense rainfall, river overflow, cloudbursts, dam failure, storm surge, and blocked drainage; impermeable urban surfaces accelerate runoff.
Flood measures: Avoid construction on floodplains, maintain drainage, restore wetlands, elevate critical facilities, evacuate early, and prohibit electrical use in submerged buildings.
Drought effects: Agricultural, hydrological, ecological, and socioeconomic droughts may cause food insecurity, groundwater depletion, migration, and conflict over water.
Drought measures: Rainwater harvesting, efficient irrigation, groundwater regulation, crop diversification, water rationing, and drought monitoring reduce vulnerability.
Example: A flash flood can provide only minutes of warning, making local sirens, marked evacuation routes, and community volunteers especially important.

IV. Air-related disasters — atmospheric hazards

A. Air-related disasters

Air-related disasters are dangerous atmospheric events involving extreme winds, pressure changes, temperature, visibility, or air quality.

Examples: Cyclones, storms, tornadoes, heat waves, cold waves, lightning, dust storms, and severe air-pollution episodes.
Health effects: Heat stress, respiratory illness, injuries from debris, disrupted transport, and increased mortality among older people and outdoor workers.
Preparedness: Weather forecasting, public alerts, cooling or warming shelters, secure buildings, emergency power, and protection of communication systems limit losses.

B. Cyclones and storms

Cyclones are large rotating low-pressure systems that produce strong winds, heavy rain, and sometimes storm surges; storms include severe convective events and thunderstorms.

Formation: Tropical cyclones require warm ocean water, moisture, and sufficient Coriolis force; they weaken over land or cooler water.
Hazards: Wind damage, coastal inundation, inland flooding, landslides, lightning, and prolonged power failure.
Early warning: Forecast tracks, staged evacuation, cyclone shelters, emergency kits, and securing roofs and loose objects reduce mortality.
Response rule: Evacuation should occur before hazardous winds begin; people should remain indoors away from windows during the storm.
Example: A coastal village may face greater danger from storm surge than wind, so elevation maps and evacuation to higher ground are crucial.

V. Earth-related disasters — hazards from the solid Earth

A. Earth-related disasters

Earth-related disasters originate in geological processes or gravity-driven movement of the ground and snow.

Major forms: Earthquakes, landslides, avalanches, volcanic eruptions, tsunamis, and ground subsidence.
Risk factors: Active faults, steep slopes, weak rock, snow accumulation, volcanic zones, unsafe buildings, and settlement in hazardous terrain.
Reduction: Seismic building codes, slope stabilization, geological zoning, monitoring, evacuation routes, and public drills lower risk.

B. Earthquakes

An earthquake is the sudden release of stored strain energy along a fault, producing seismic waves and ground shaking.

Measurement: Magnitude describes released energy; intensity describes observed effects at a location. The moment magnitude scale is commonly used for large earthquakes.
Primary hazards: Ground shaking, surface rupture, liquefaction, fires, infrastructure collapse, and tsunamis in offshore events.
Safety action: “Drop, Cover, and Hold On”; after shaking, evacuate damaged buildings, expect aftershocks, and avoid lifts.
Preparedness: Retrofitting, flexible utility connections, secured furniture, emergency supplies, and earthquake-resistant design are essential.
Example: Liquefaction occurs when saturated loose soil loses strength during shaking, causing buildings to tilt or sink even without direct fault rupture.

C. Landslides

Landslides are the downslope movement of rock, soil, or debris under gravity, often triggered by rainfall, earthquakes, erosion, or human excavation.

Warning signs: Ground cracks, tilted trees or poles, bulging road surfaces, blocked drains, and new water seepage.
Risk reduction: Drainage control, retaining structures, slope vegetation, regulated road cutting, hazard zoning, and relocation from unstable slopes.
Response: Move laterally away from the slide path, avoid valleys and river channels, and never cross an active debris flow.
Human factor: Deforestation and poorly designed construction remove slope support and increase infiltration.

D. Avalanches

Avalanches are rapid downward movements of snow, ice, and debris on steep mountain slopes.

Triggers: Heavy snowfall, wind loading, rapid warming, vibration, and weak layers within the snowpack.
Precautions: Avalanche forecasts, route closure, transceivers, probes, shovels, helmets, trained guides, and travel in separated groups.
Rescue: Companions should mark the last-seen point, search immediately with transceivers, uncover the airway first, and summon professional rescue.
Limitation: Forecasts reduce exposure but cannot eliminate risk because snow conditions can change quickly.

E. Volcanic eruptions

Volcanic eruptions occur when magma, gases, ash, and fragmented rock reach the surface through volcanic vents.

Hazards: Lava flows, ash fall, pyroclastic flows, lahars, toxic gases, earthquakes, and aviation disruption.
Monitoring: Seismic activity, ground deformation, gas emissions, thermal changes, and crater observations provide warning indicators.
Protection: Follow exclusion zones, evacuate along planned routes, wear masks and eye protection during ash fall, and protect water supplies.
Long-term measure: Land-use planning should prevent permanent settlement in channels exposed to lahars or pyroclastic flows.

VI. Manmade disasters — failures caused by human activity

A. Manmade disasters

Manmade disasters result from technological failures, unsafe practices, conflict, negligence, or intentional acts.

Examples: Nuclear and chemical accidents, industrial fires, biological incidents, transport crashes, oil spills, structural collapse, and terrorism.
Root causes: Poor maintenance, inadequate regulation, human error, defective design, weak safety culture, and delayed reporting.
Prevention: Risk assessment, safety audits, training, emergency plans, monitoring, redundancy, regulation, and accountability are central.

B. Nuclear disasters

Nuclear disasters involve uncontrolled release of radioactive material or radiation from reactors, fuel facilities, weapons, or transport.

Hazards: External exposure, internal contamination, acute radiation sickness, increased cancer risk, and long-term environmental contamination.
Protective actions: Get indoors, reduce exposure time, increase distance and shielding, follow official instructions, and evacuate when directed.
Emergency control: Authorities monitor radiation, establish exclusion zones, decontaminate people and equipment, distribute appropriate medicines, and control food and water.
Principle: Radioactive contamination is not reliably identified by sight or smell; official monitoring is necessary.

C. Chemical disasters

Chemical disasters involve toxic, corrosive, flammable, or reactive substances released during production, storage, transport, or use.

Immediate danger: Inhalation, skin or eye contact, fire, explosion, and chemical reaction with water or other substances.
Response: Raise the alarm, isolate the area, move upwind or crosswind, avoid touching containers, and use trained hazardous-material teams.
Preparedness: Safety data sheets, labeling, leak detectors, personal protective equipment, buffer zones, and community warning systems are required.
Example: A toxic gas cloud may travel with wind, so sheltering indoors with sealed openings can be safer than spontaneous movement through the plume.

D. Biological disasters

Biological disasters are large-scale disease events caused by pathogens, toxins, or deliberate biological release.

Transmission controls: Surveillance, testing, isolation, treatment, vaccination, hand hygiene, ventilation, and risk communication interrupt spread.
Preparedness: Laboratories, stockpiles, infection-control procedures, trained health workers, and continuity plans protect essential services.
Response principle: Measures should be proportionate, evidence-based, and respectful of privacy and human rights.
Community role: Early reporting of unusual illness and cooperation with health guidance improve outbreak control.

E. Transport accidents

Transport accidents include crashes or hazardous-material incidents involving road, rail, air, or water transport.

Common causes: Speed, fatigue, poor maintenance, unsafe infrastructure, weather, operator error, and inadequate regulation.
First response: Protect the scene, call emergency services, prevent fire or secondary collisions, provide only safe first aid, and avoid moving spinal-injury victims unnecessarily.
Prevention: Seat belts, helmets, safe speeds, vehicle inspection, competent operators, signaling systems, and emergency access routes reduce casualties.

VII. National disaster management framework — coordinated risk governance

A. National disaster management framework

A national framework assigns legal authority, responsibilities, standards, funding, and coordination mechanisms across disaster phases.

Core components: Risk assessment, prevention, preparedness, early warning, emergency operations, relief, rehabilitation, recovery, and reconstruction.
Institutional levels: National bodies develop policy and resources; state or provincial bodies coordinate regionally; local authorities implement plans.
Operational principle: Incident command clarifies leadership, while emergency operation centres integrate information, logistics, communications, and resource allocation.
Planning standard: Plans should identify hazards, vulnerable groups, shelters, routes, stockpiles, communication channels, and continuity arrangements.

VIII. Role of governmental agencies in disaster response — public authority

A. Role of governmental agencies in disaster response

Government agencies provide lawful command, specialized services, public infrastructure, relief, and long-term recovery.

Emergency services: Police manage security and evacuation; fire services conduct rescue and hazardous-material control; health departments provide triage and treatment.
Technical agencies: Meteorological, geological, water, and public-works agencies monitor hazards, issue warnings, inspect structures, and restore lifelines.
Relief administration: Authorities coordinate food, water, shelter, sanitation, compensation, missing-person records, and protection of vulnerable people.
Accountability: Transparent procurement, accurate damage assessment, non-discrimination, and public information reduce corruption and exclusion.

IX. Role of NGOs in disaster response — flexible humanitarian support

A. Role of NGOs in disaster response

Non-governmental organizations supplement public action through specialized services, local networks, advocacy, and rapid humanitarian assistance.

Immediate services: NGOs may provide search support, emergency shelter, food, water, sanitation, medical care, psychosocial support, and protection services.
Coordination: They should share assessments through official coordination systems and avoid duplicating aid in accessible areas while neglecting isolated communities.
Recovery: NGOs support livelihood restoration, temporary education, housing repair, disaster-risk training, and inclusion of women, children, older persons, and people with disabilities.
Safeguard: Aid must be needs-based, culturally appropriate, accountable, and protected from political or commercial exploitation.

X. Role of community-based organizations in disaster response — local capacity

A. Role of community-based organizations in disaster response

Community-based organizations provide trusted, neighborhood-level action before formal assistance arrives and help ensure that response reflects local needs.

Preparedness: They map vulnerable households, maintain local volunteer teams, conduct drills, identify shelters, and preserve indigenous knowledge.
Immediate response: Local groups often provide first aid, evacuation assistance, rescue information, food distribution, and missing-person tracing.
Inclusion: Community participation helps reach people who may be overlooked, including renters, migrants, isolated elders, and persons with disabilities.
Recovery: Local organizations monitor relief distribution, organize debris removal, restore livelihoods, and advocate for safer reconstruction.

XI. Role of media in disaster response — information and public accountability

A. Role of media in disaster response

Media connect authorities, responders, and the public by delivering timely warnings, explaining protective action, and reporting unmet needs.

Warning function: Broadcasts can communicate evacuation zones, shelter locations, weather updates, and emergency numbers through television, radio, print, and digital platforms.
Public education: Clear explanations such as “boil drinking water” or “do not enter damaged buildings” convert technical advice into practical behavior.
Accountability: Responsible reporting documents gaps, counters rumors, and highlights marginalized communities without obstructing rescue operations.
Ethical standard: Verify information, identify sources, protect survivors’ dignity, avoid graphic exposure and panic, and distinguish confirmed facts from speculation.
Two-way communication: Social media and community radio can collect real-time reports, but information must be checked before amplification.