Unit 5: Disaster management

I. Orientation: Hazard, Vulnerability and Disaster

A disaster is not the hazard itself but the collision of a hazard with a vulnerable, exposed population that exceeds local coping capacity. The Disaster Management Act, 2005 (India) defines disaster as "a catastrophe, mishap, calamity or grave occurrence… arising from natural or man-made causes… which is beyond the coping capacity of the community of the affected area." India is uniquely exposed: roughly 59% of the landmass is earthquake-prone, over 40 million hectares are flood-prone, and about 5,700 km of the 7,516 km coastline is cyclone- and tsunami-prone.

Defining terms and conventions used throughout:

• Hazard: the physical event with damage potential — a magnitude 7.6 earthquake, a 200 km/h wind, a 15 m storm surge.
• Vulnerability: conditions that increase susceptibility — unreinforced masonry housing, settlement on floodplains, poverty, age, disability.
• Exposure: people, assets and infrastructure located in the hazard zone.
• Capacity: resources to resist and recover — early warning systems, cyclone shelters, insurance, trained volunteers.
• Risk equation:

Risk = (Hazard × Vulnerability × Exposure) / Capacity

• Disaster cycle (four phases): mitigation (long-term risk reduction) → preparedness (plans, drills, stockpiles) → response (search, rescue, relief within hours to weeks) → recovery/rehabilitation and reconstruction (months to years).
• Classification convention: natural disasters are grouped as water-related, air-related (atmospheric) and earth-related (geological); anthropogenic disasters are grouped by causal agent — nuclear, chemical, biological, technological/transport.

II. Natural Disasters: Water Related

Hydrological extremes at both ends of the distribution — excess and deficit — are India's most frequent and most widespread disasters, both governed by the monsoon.

A. Floods and Drought

1. Floods

• Definition and cause: inundation when discharge exceeds channel capacity; in India 75% of annual rainfall falls in the June–September southwest monsoon, concentrating runoff in ~100 days.
• Types: riverine (Ganga–Brahmaputra–Meghna basin), flash floods (Uttarakhand, Kedarnath 2013), urban floods from clogged drains and lost wetlands (Mumbai 26 July 2005, 944 mm in 24 hours; Chennai 2015), coastal floods from storm surge, and glacial lake outburst floods (GLOFs).
• Human aggravators: deforestation in catchments, siltation of riverbeds, encroachment of floodplains, embankment failure, unplanned dam releases.
• Impacts: drowning, crop loss, waterborne epidemics (cholera, leptospirosis, hepatitis A), topsoil loss, displacement.
• Mitigation: embankments and levees, detention basins, afforestation of catchments, floodplain zoning, Central Water Commission flood forecasting, raised plinth housing.

2. Drought

• Definition: prolonged deficiency of water; meteorological drought is declared when seasonal rainfall is more than 25% below normal (more than 50% = severe).
• Types: meteorological (rainfall deficit), hydrological (depleted reservoirs and groundwater), agricultural (soil moisture insufficient for crops), and socio-economic (failure of food and income systems).
• Trigger mechanism: El Niño–Southern Oscillation warm phases correlate with weak Indian monsoons; drought-prone areas include Rajasthan, Marathwada, Bundelkhand, Rayalaseema.
• Impacts: crop failure, livestock death, distress migration, desertification, farmer suicides — a slow-onset "creeping" disaster with no single point of impact.
• Mitigation: watershed development, check dams and percolation tanks, drought-resistant millets, drip irrigation, MGNREGA-based water conservation works, crop insurance (PMFBY).

III. Natural Disasters: Air Related

Atmospheric disasters arise from pressure gradients and convective instability; unlike earthquakes they are forecastable, so warning lead time is the decisive variable.

A. Cyclone and Storms

1. Tropical cyclones

• Formation conditions: sea surface temperature ≥ 26.5 °C to a depth of ~60 m, low vertical wind shear, pre-existing disturbance, latitude beyond ~5° for Coriolis force.
• Structure: calm eye (20–50 km diameter) of subsiding air, surrounded by the eyewall of maximum winds, then spiral rain bands.
• Indian seasons and basins: Bay of Bengal (about 4:1 more frequent than the Arabian Sea), peaking pre-monsoon (April–May) and post-monsoon (October–December).
• IMD intensity scale: Depression (31–49 km/h) → Cyclonic Storm (62–88) → Severe (89–117) → Very Severe (118–166) → Extremely Severe (167–221) → Super Cyclone (≥222 km/h).
• Killer mechanism: the storm surge, not wind — the 1999 Odisha Super Cyclone produced surges of 5–6 m and about 10,000 deaths; by Cyclone Phailin (2013) mass evacuation of ~1 million people cut deaths to under 50.
• Mitigation: cyclone shelters, mangrove and shelterbelt plantation, INSAT and Doppler radar tracking, colour-coded IMD bulletins, evacuation drills.

2. Local and severe storms

• Thunderstorms and lightning: convective; lightning is India's largest single natural-disaster killer, causing roughly 2,000–2,500 deaths annually.
• Tornadoes and nor'westers ("Kalbaisakhi"): violent pre-monsoon squalls over Bengal, Bihar and Assam.
• Dust storms and hailstorms: andhi in northwest India; hail destroys standing rabi crops.

IV. Natural Disasters: Earth Related

Geological disasters originate in the lithosphere, are largely unpredictable in timing, and are governed by plate tectonics and slope stability.

A. Earthquakes, Landslides, Avalanches, Volcanic Eruptions

1. Earthquakes

• Mechanism: elastic rebound — strain accumulated along faults released as seismic waves (P, S, and surface L waves) from the focus; the epicentre is the surface point above it.
• Measurement: Richter magnitude is logarithmic (each unit = ~31.6× energy release); Modified Mercalli scale measures observed intensity I–XII.
• Indian seismic zoning (IS 1893): Zone II (low) to Zone V (very high — Kashmir, Himachal, Uttarakhand, northeast India, Kutch, Andaman & Nicobar).
• Case anchors: Bhuj, Gujarat, 26 January 2001, M 7.7, ~20,000 deaths; Latur 1993 in a supposedly stable shield region.
• Mitigation: it is buildings, not earthquakes, that kill — ductile detailing, shear walls, base isolation, retrofitting, enforcement of building bye-laws.

2. Landslides

• Causes: heavy rainfall saturating regolith, slope cutting for roads, deforestation, seismic shaking; classified as falls, slides, flows and creep.
• Vulnerable belts: Himalayas, Western Ghats, Nilgiris; Malin (Maharashtra) 2014 buried an entire village.
• Mitigation: retaining walls, benching and terracing, surface and subsurface drainage, bio-engineering with deep-rooted grasses, hazard-zonation mapping by GSI.

3. Avalanches

• Definition: rapid downslope movement of a snow mass, typically on slopes of 30–45°, triggered by fresh snowfall, temperature rise or vibration.
• Types: loose-snow (point release) and slab avalanches (the more lethal).
• Indian context: Himachal, Jammu & Kashmir, Uttarakhand; military posts such as Siachen; forecast by DRDO's Defence Geoinformatics Research Establishment.
• Mitigation: snow bridges and fences, controlled artificial release, avoiding construction in avalanche paths, beacons and probes for rescue.

4. Volcanic eruptions

• Mechanism: ascent of magma along plate margins or hot spots; hazards are lava flows, pyroclastic flows, lahars, ashfall and volcanic gases (SO₂, CO₂).
• Indian context: Barren Island in the Andaman Sea is India's only active volcano; Narcondam is dormant; the Deccan Traps are a fossil flood-basalt province.
• Global significance: ash injection cools climate — Tambora 1815 caused the 1816 "year without a summer"; ash clouds also ground aviation.

V. Manmade Disasters

Anthropogenic disasters arise from technology, industry and pathogens, and are distinguished by being in principle preventable through regulation, design and drill.

A. Nuclear Disasters

• Sources: reactor core meltdown, criticality accidents, radioactive waste leakage, transport of isotopes, radiological dispersal ("dirty bomb").
• Anchors: Chernobyl, 26 April 1986 (INES Level 7); Fukushima Daiichi, 11 March 2011, triggered by a M 9.0 earthquake and tsunami.
• Effects: acute radiation syndrome above ~1 Sv, thyroid cancer from I-131, long-lived contamination from Cs-137 (half-life 30 years) and Sr-90.
• Protection: time–distance–shielding principle, potassium iodide prophylaxis, exclusion zones, AERB regulation and defence-in-depth containment design.

B. Chemical Disasters

• Sources: industrial gas leaks, storage tank explosions (BLEVE), pipeline rupture, hazardous-waste dumping.
• Anchor: Bhopal gas tragedy, night of 2–3 December 1984 — release of ~40 tonnes of methyl isocyanate (MIC) from Union Carbide; thousands died within days, with lasting respiratory and ocular morbidity.
• Governing rules: Environment (Protection) Act 1986; Manufacture, Storage and Import of Hazardous Chemical Rules 1989; Chemical Accidents (EPPR) Rules 1996; Public Liability Insurance Act 1991.
• Mitigation: MSDS documentation, buffer zones around plants, on-site and off-site emergency plans, gas detectors, safety audits, mock drills.

C. Biological Disasters

• Definition: disasters caused by pathogens or toxins — epidemics, pandemics, zoonoses, pest infestations, bioterrorism (e.g. anthrax spores).
• Anchors: COVID-19 declared a pandemic by WHO on 11 March 2020; Nipah outbreak in Kerala, 2018; recurrent dengue and plague (Surat, 1994).
• Amplifiers: high density, air travel, poor sanitation, antimicrobial resistance, wildlife-trade spillover.
• Response tools: surveillance and contact tracing (IDSP), quarantine and isolation, ring vaccination, PPE and biosafety levels BSL-1 to BSL-4, International Health Regulations (2005).

D. Transport Accidents

• Modes and typical causes: road (over-speeding, drunk driving — India records roughly 1.5 lakh road deaths annually), rail (derailment, signal failure, level-crossing collision), air (mechanical and human error), marine (oil spills such as the Exxon Valdez, 1989).
• Compound risk: tankers carrying LPG or chlorine turn an accident into a chemical disaster, e.g. road-tanker rollovers near settlements.
• Mitigation: Motor Vehicles (Amendment) Act 2019 penalties, anti-collision devices and Kavach on railways, black-box analysis, "golden hour" trauma care and helmet/seat-belt enforcement.

VI. Disaster Management

A. National Disaster Management Framework

The Disaster Management Act, 2005 shifted India from a relief-centric to a proactive, prevention-and-preparedness-centric regime, creating a three-tier institutional structure.

• NDMA: National Disaster Management Authority, chaired by the Prime Minister; lays down policies, plans and guidelines.
• SDMA and DDMA: chaired by the Chief Minister and the District Collector respectively; the DDMA is the operational nerve centre at district level.
• Executive arms: National Executive Committee (Union Home Secretary); NIDM for training and research; NDRF (12 battalions) as the specialist response force.
• Instruments: National Disaster Management Plan (2016, revised 2019) aligned with the four priorities of the Sendai Framework for Disaster Risk Reduction 2015–2030; National Disaster Response Fund and State Disaster Response Fund.
• Nodal agencies by hazard: IMD (cyclones, earthquakes), CWC (floods), GSI (landslides), BARC/AERB (nuclear).

B. Role of Governmental Agencies

• Home Ministry: nodal ministry for overall coordination and NDRF deployment.
• Armed forces: last-resort but first-visible responders — engineering task forces, helicopter rescue, field hospitals (Uttarakhand 2013 airlift of over 100,000 pilgrims).
• Local administration: the Collector issues evacuation orders, runs relief camps and certifies damage for compensation.
• Technical agencies: ISRO's NRSC supplies satellite damage mapping; NIC runs India Disaster Resource Network.

C. Role of NGOs

• Comparative advantage: flexibility, local trust and speed where bureaucracy is slow — Red Cross/IRCS, Oxfam, CARE, SEEDS, Ramakrishna Mission.
• Functions: relief distribution, temporary shelter, psychosocial counselling, livelihood restoration, and advocacy for equitable compensation.
• Coordination need: unregulated NGO influx causes duplication and "second disaster" of unsorted donations; Sphere Standards define minimum humanitarian benchmarks.

D. Role of Community-Based Organisations

• Rationale: neighbours perform most rescues in the first 24 hours, before external teams arrive.
• Mechanisms: village Disaster Management Committees and task forces (warning, search-rescue, first aid, shelter), Aapda Mitra volunteers, SHGs channelling micro-credit for recovery.
• Tools: participatory hazard mapping, community seed and grain banks, mock drills embedded in school safety programmes.
• Indigenous knowledge: stilt houses in Assam, bamboo ikra construction in the northeast, traditional flood-cropping calendars.

E. Role of Media

• Warning dissemination: amplifying IMD bulletins through radio, TV tickers, SMS cell broadcast and social media — the decisive channel in the Phailin evacuation.
• Awareness and education: pre-season programming on evacuation routes and do's and don'ts.
• Watchdog and accountability: exposing relief diversion and slow rehabilitation.
• Risks: sensationalism, rumour and panic amplification, intrusion on victims' dignity, and obstruction of rescue operations — arguing for accredited reporting and verified-source protocols.