FLOODS
Floods are the most common and widespread of all natural disasters. India is one of the highly
flood prone countries in the world. Around 40 million hectares of land in India is prone to floods
as per National Flood Commission report. Floods cause damage to houses, industries, public
utilities and property resulting in huge economic losses, apart from loss of lives. Though it is not
possible to control the flood disaster totally, by adopting suitable structural and non-structural
measures the flood damages can be minimized. For planning any flood management measure
latest, reliable, accurate and timely information is required. In this context satellite remote
sensing plays an important role.
When Do They Occur?
•
•
•
Floods can occur any time of the year.
Floods occur primarily in the spring season due to ice and snow melting and frequent storms.
In some countries, there are monsoon seasons, a time of great rain, when floods often occur.
Where Do Floods Often Occur?
•
•
•
Floods occur all over the world, except for in Antarctica. Highlands are also unlikely to be
struck by flooding.
They often occur in urban areas where water cannot drain into the soil properly.
Floods usually affect floodplains, low lying, and flat areas near large bodies of water.
Weather That Causes Floods:
•
•
Floods are caused by melting snow and ice, severe storms, hurricanes, tropical storms,
monsoons, or prolonged or sudden rain fall.
El Niño is a major contributor to flooding globally.
CONTROL
In many countries across the world, rivers prone to floods are often carefully managed. Defenses
such as levees, bunds, reservoirs, and weirs are used to prevent rivers from bursting their banks.
When these defenses fail, emergency measures such as sandbags or portable inflatable tubes are
used. Coastal flooding has been addressed with coastal defences e.g. sea walls, beach
nourishment, and barrier islands.
In India, Bangladesh and China, flood diversion areas are rural areas that are deliberately
flooded in emergencies in order to protect cities. With natural forest cover the flood duration
decreases. Reduction in the rate of deforestation decreases the incidents and severity of floods.
RESCUE AND EVACUATION
Evacuation is a pre-emptive move to protect life and property, where as rescue is a post-disaster
phenomenon of helping people to move from areas that have been hit by disaster to a safer place.
However, during such the situations, following precautionary norms should be kept in mind.
1
EduFirm
PREPARING FOR A FLOOD
 Contact the local geologist or town planning department to find out if your home is located
in a flash-flood-prone area.
 Learn about your community's emergency plans, warning signals, evacuation routes, and
locations of emergency shelters.
 Plan and practice a flood evacuation route with your family. Ask an out-of-state relative to
be the "family contact" in case your family is separated during a flood.
 Inform local authorities about any special needs, i.e., elderly or bedridden people..
 Identify potential home hazards and know how to secure or protect them before the flood
strikes e.g. turn off electrical power, gas and water supplies before you evacuate.
 Buy a fire extinguisher and make sure your family knows where it is and how to use it.
 Buy and install pumps with back-up power.
 For drains, toilets, and sewer connections, install backflow valves to prevent floodwaters
from entering.
 Anchor fuel tanks which can contaminate your basement if torn free.
EMERGENCY SUPPLIES












Several clean containers for water for a 3-5 day supply of water.
A 3-5 day supply of non-perishable food.
A first aid kit and manual and prescription medicines.
A battery-powered radio, flashlights, and extra batteries.
Sleeping bags or extra blankets.
Water-purifying supplies e.g. chlorine or iodine tablets.
Baby food and diapers.
Disposable cleaning cloths e.g. "baby wipes" for the whole family to use in case bathing
facilities are not available.
Personal hygiene supplies e.g. soap, toothpaste etc.
An emergency kit for your car with food, flares, booster cables, maps, tools, a first aid kit,
fire extinguisher, sleeping bags, etc.
Rubber boots and waterproof gloves.
Insect repellent, screens, or long-sleeved clothing for protection from mosquitoes.
Preparing to Evacuate
Expect the need to evacuate and prepare for it. When a flood watch is issued, you should:
 Fill your vehicle's gas tank and make sure the emergency kit for your car is ready.
 If no vehicle is available, make arrangements with friends or family for transportation.
 Fill your clean water containers.
 Review your emergency plans and supplies, checking to see if any items are missing.
 Tune in the radio or television for weather updates.
 Listen for disaster sirens and warning signals.
2
EduFirm
 Put livestock and family pets in a safe area.
IF YOU ARE UNDER A FLOOD
 Gather the emergency supplies you previously stocked in your home and stay tuned to local
radio or television station for updates.
 Turn off all utilities at the main power switch and close the main gas valve.
 Fill bathtubs, sinks and plastic soda bottles with clean water.
CLEAN-UP SAFETY
Clean-up activities following floods often pose hazards to workers and volunteers involved in the
effort. Potential dangers include:







Water polluted by mixing with sanitary sewers
Electrical hazards
Carbon monoxide exposure
Musculoskeletal hazards
Heat or cold stress
Motor vehicle-related dangers
Fire, drowning, and exposure to hazardous materials.
BENEFITS OF FLOODS
 Recharging of ground water.
 Make soil more fertile and provide nutrients in which it is deficient.
 Flood waters provide much needed water resources in arid and semi-arid regions where
precipitation is very unevenly distributed throughout the year.
 Freshwater floods play an important role in maintaining ecosystems in rivers and floodplain
biodiversity.
 Flooding adds a lot of nutrients to lakes and rivers which leads to improved fisheries for a
few years. Together with fish also birds profit from the boost in production caused by
flooding.
 The viability for hydrological based renewable sources of energy is higher in flood prone
regions.
3
EduFirm
LIST OF DEADLIEST FLOODS
Death toll
Event
Location
Date
2,500,000–3,700,000
1931 China floods
China
1931
900,000–2,000,000
1887 Yellow River (Huang He) flood
China
1887
500,000–700,000
1938 Yellow River (Huang He) flood
China
1938
231,000
Banqiao Dam failure, result of Typhoon Nina.
Approximately 86,000 people died from flooding
and another 145,000 died during subsequent
disease.
China
1975
230,000
Indian Ocean tsunami
Indonesia
2004
145,000
1935 Yangtze river flood
China
1935
100,000+
St. Felix's Flood, storm surge
Netherlands
1530
100,000
Hanoi and Red River Delta flood
North
Vietnam
1971
100,000
1911 Yangtze river flood
China
1911
4
EduFirm