How hazards become disasters, how they are classified, India’s earthquakes, floods, droughts, cyclones, tsunamis and landslides, and the stages of disaster management.
Key ideas
A hazard becomes a disaster when it strikes suddenly and causes damage beyond people’s capacity to cope.
Natural hazards are atmospheric (cyclones, droughts, blizzards), terrestrial (earthquakes, landslides), aquatic (floods, tsunamis) or biological.
The Indian plate moves about 1 cm a year north and north-east against the Eurasian plate, so stress builds up and earthquakes strike the Himalayas and the north-east.
Tropical cyclones form between about 30° N and 30° S but not within 5° of the equator, where the Coriolis force is absent; storm surges flood the coasts.
Floods are made worse by deforestation, blocked drainage and settling on floodplains, though they also leave fertile silt.
Droughts may be meteorological, agricultural, hydrological or ecological; rainwater harvesting and drought-resistant crops help.
Disaster management has three stages: preparedness before, rescue and relief during, and rehabilitation after.
Remember
Plate movement
1 cm a year: metres = years ÷ 100
Drought-prone rule
an area with over 30% of its gross cropped area irrigated is excluded
Flood-prone land
about 40 million hectares (National Flood Commission)
Share of an area
per cent × area ÷ 100
Famine words
akal food grains; trinkal fodder; jalkal water; trikal all three
Yokohama Strategy
World Conference on disaster reduction, May 1994
Watch out
Calling a tsunami atmospheric (it is aquatic) or a drought aquatic (it is atmospheric).
Including a district with more than 30% irrigated area as drought-prone.
Thinking tropical cyclones form right at the equator.
Worked example
Areas with more than 30 per cent of their gross cropped area irrigated are excluded from the drought-prone category. Is each district included or excluded? (a) 35% irrigated (b) 60% irrigated