Disasters like floods can be caused by both natural hazards like heavy rainfall or snowmelt as well as human factors like infrastructure failure or climate change. A disaster occurs when a hazard impacts a vulnerable population, causing damage, casualties, and disruption. Floods can have both positive effects like enriching soil but also negative consequences like property damage. Prevention methods aim to reduce the impact of hazards through activities like building levees, retaining walls, and educating communities, while response focuses on emergency relief during and after flooding occurs. India experiences frequent flooding in areas along major river systems.

1. Disaster
• French word “Desastre”
• ‘des’ meaning bad and ‘aster’ meaning star
• Refers to ‘Bad or Evil star’.
Disaster means a catastrophe, mishap, calamity or grave occurrence in any area, arising from
natural or man made causes, or by accident or negligence which results in substantial loss of
life or human suffering or damage to, and destruction of, property, or damage to, or
degradation of, environment, and is of such a nature or magnitude as to be beyond the coping
capacity of the community of the affected area (definition according to Disaster Management
Act 2005, Government of India)
A disaster happens when a hazard impacts on the vulnerable population and causes damage,
casualties and disruption.
Hazard
A dangerous phenomenon, substance, human activity or condition that may cause loss of life,
injury or other health impacts, property damage, loss of livelihoods and services, social and
economic disruption, or environmental damage. Hazards arise from a variety of geological,
meteorological, hydrological, oceanic, biological, and technological sources, sometimes
acting in combination. In technical settings, hazards are described quantitatively by the likely
frequency of occurrence of different intensities for different areas, as determined from
historical data or scientific analysis. The two types of hazards are -
 Natural hazard
 Technological hazards
Vulnerability
The extent to which a community, structure, services or geographic area is likely to be
damaged or disrupted by the impact of particular hazard, on account of their nature,
construction and proximity to hazardous terrains or a disaster prone area.
DISASTER MANAGEMENT
Disaster management is a process of effectively preparing for and responding to disasters. It
involves strategically organizing resources to lessen the harm that disasters cause. It also
involves a systematic approach to managing the responsibilities of disaster prevention,
preparedness, response, and recovery.
DISASTER MANAGEMENT CYCLE

2. Includes sum total of all activities,
programmes and measures taken up before,
during, and after a disaster with the purpose
to avoid a disaster, reduce its impact or
recover from its losses. The three key stages
of activities within disaster risk management
are:
1. Before a disaster (pre-disaster).
Activities to reduce human and
property losses caused by a potential hazard. Example, by carrying out awareness
campaigns, strengthening the existing weak structures, preparation of the disaster
management plans at household and community level etc. Such risk reduction
measures taken under this stage are termed as mitigation and preparedness activities.
2. During a disaster (disaster occurrence).
Initiatives taken to ensure the needs and provisions of victims are met and suffering is
minimized. Activities taken under this stage are called emergency response activities.
3. After a disaster (post-disaster)
Initiatives taken in response to a disaster with a purpose to achieve early recovery and
rehabilitation of affected communities, immediately after a disaster strikes. These are
called as response and recovery activities.
DISASTER EMERGENCY KIT
When a natural disaster occurs, we can't always
rely on police or governments to provide help.
The grocery store might be so badly damaged
that you can't go into it. The supplies in the store
might be quickly depleted or you may not be
able to get to the store. the six basic supplies you
need in a disaster kit are:
 Water
 Food
 First aid supplies
 Clothing, bedding and sanitation supplies
 Tools
 Special items
FLOOD
A flood is an overflow of an expanse of water that submerges land. Flood is defined as a
covering by water of land which is not normally covered by water. In the sense of "flowing
water", the word may also be applied to the inflow of the tide. Flooding may result from the

3. volume of water within a body of water, such as a river or lake, which overflows or breaks
levees, with the result that some of the water escapes its usual boundaries.
Floods often cause damage to homes and businesses if they are placed in natural flood plains
of rivers. While flood damage can be virtually eliminated by moving away from rivers and
other bodies of water, since time out of mind, people have lived and worked by the water to
seek sustenance and capitalize on the gains of cheap and easy travel and commerce by being
near water. That humans continue to inhabit areas threatened by flood damage is evidence
that the perceived value of living near the water exceeds the cost of repeated periodic
flooding.
Causes of Floods
Flood is usually a result of natural causes. It may also be caused by man-made factors. There
are many different causes leading to flooding. Some prominent among them include:
 Massive Rainfall
 Overflowing of the Rivers
 Collapsed Dams
 Snowmelt
 Deforestation
 Climate change
 Emission of Greenhouse Gases
 Other Factors

4. Effects of flooding
Effects of flooding can be both positive and negative.
For millennia, people have settled near rivers and lakes because water is easily accessible
and the soil is fertile. Back in the days though, people constructed on higher grounds
allowing riverine floods to enrich the land with nutrients. Floods are in reality very important
processes for the natural environment. And humans also benefit from them. However, they
also have a number of negative effects.
Positive effects of flooding
In many rural regions around the world, the livelihoods of many communities depend on
annual flood cycles. Examples include riverine settlements along the Amazon forest like
Peruvian and Columbian communities. This is because floods facilitate transportation, fish
migrations and make the soil fertile. Thus, seasonal flooding has many positive effects such
as
1. Flooding makes the land fertile

5. 2. Flooding adds nutrients to the sea
3. Dislodges accumulated debris
4. Supplies sediment to deltas
5. Floods recharge groundwater
6. Flooding balances the health of wetlands
a. Helps to maintain chemical balance
b. Restore breeding grounds
c. Increase biodiversity stock
Negative effects of flooding
We have to keep in mind that flooding is a natural process in the environment. It becomes a
problem when people live/build too close to floodplains. Or when they modify the land so
much that it can no longer absorb water. So, the negative effects of flooding are -
1. Floods damage built infrastructure
2. Flooding leads to economic losses
3. Loss of lives and social disruption
4. Extreme floods cause erosion
5. Flooding causes algal blooms

6. TYPES OF FLOODS
Over recent years, floods have hit the headlines on several occasions. But not all floods are
equal and there are in fact many different types.
1. Coastal Flooding

7. 2. River Flooding
3. Flash Flooding
4. Groundwater Flood
5. Drain and Sewer Flooding
FLASH FLOOD Vs RIVER FLOOD
Flash floods are distinguished from a regular flood by a timescale of less than six hours
Flood prone area in India
The states falling within the periphery of "India Flood Prone Areas" are West Bengal, Orissa,
Andhra Pradesh, Kerala, Assam, Bihar, Gujrat, Uttar Pradesh, Haryana and Punjab. The
intense monsoon rains from southwest causes rivers like Brahmaputra, Ganga, Yamuna etc.
to swell their banks, which in turn floods the adjacent areas.
Over the past few decades, central India has become familiar with precipitation events like
torrential rains and flash floods. The major flood prone areas in India are the river banks and
deltas of Ravi, Yamuna-Sahibi, Gandak, Sutlej, Ganga, Ghaggar, Kosi, Teesta, Brahmaputra,
Mahanadi, Mahananda, Damodar, Godavari, Mayurakshi, Sabarmati and their tributaries.

9. An over-view about state-wise flood prone areas can be gained by checking the following
table:
Highest flood prone areas in India
Though the north-Indian plains prone to flood more, the "India flood prone areas" can be
broadly categorized in three divisions:
1. Ganga Basin
2. Brahmaputra and Barak Basins
3. Central India and Deccan Rivers Basin
Average Annual Flood Damage (1953 - 1999)
Total Damage Rs.13,400 million
Area Affected 8.11 million hectare
Crop Area Affected 3.57 million hectare
Human Lives Lost 1579 Nos.
Cattle Lost 95,000 Nos.
State Area liable to Floods (million Ha.)
Uttar Pradesh 7.336
Bihar 4.26
Punjab 3.7
Rajasthan 3.26
Assam 3.15
West Bengal 2.65
Haryana 2.35
Orissa 1.4
Andhra Pradesh 1.39
Gujarat 1.39
Kerala 0.87
Tamil Nadu 0.45
Tripura 0.33
Madhya Pradesh 0.26
Himachal Pradesh 0.23
Maharashtra 0.23
Jammu & Kashmir 0.08
Manipur 0.08
Delhi 0.05
Karnataka 0.02
Meghalaya 0.02
Pondichery 0.01
Total 33.516

10. Preparing for floods (Do’s and don’ts)
To prepare for a flood, one should:
 Avoid building in flood prone areas unless you elevate and reinforce your home.
 Elevate the furnace, water heater, and electric panel if susceptible to flooding.
 Install "Check Valves" in sewer traps to prevent floodwater from backing up into the
drains of your home.
 Contact community officials to find out if they are planning to construct barriers
(levees, beams and floodwalls) to stop floodwater from entering the homes in your
area.
 Seal the walls in your basement with waterproofing compounds to avoid seepage.
If a flood is likely to hit one’s area, one should:
 Listen to the radio or television for information.
 Be aware that flash flooding can occur. If there is any possibility of a flash flood,
move immediately to higher ground. Do not wait for instructions to move.
 Be aware of streams, drainage channels, canyons, and other areas known to flood
suddenly. Flash floods can occur in these areas with or without such typical warnings
as rain clouds or heavy rain.
If one must prepare to evacuate, one should:
 Secure your home. If you have time, bring in outdoor furniture. Move essential items
to an upper floor.
 Turn off utilities at the main switches or valves if instructed to do so. Disconnect
electrical appliances. Do not touch electrical equipment if you are wet or standing in
water.
If you have to leave your home, remember these evacuation tips:
 Do not walk through moving water. Six inches of moving water can make you fall. If
you have to walk in water, walk where the water is not moving. Use a stick to check
the firmness of the ground in front of you.
 Do not drive into flooded areas. If floodwaters rise around your car, abandon the car
and move to higher ground if you can do so safely. You and the vehicle can be quickly
swept away.

13. Recent floods in India (2019-2021)
 August 2019 Indian floods including 2019 Kerala floods: Following high rain in late
July and early August 2019, series of floods that affected over nine states in India. The
states of Kerala, Madhya Pradesh, Karnataka, Maharashtra and Gujarat were the most
severely affected.
 Brahmaputra floods: The 2019 Brahmaputra Floods, till 16 July, affected a total of
52,59,142 people, 1,63,962.02 hectares of crop area, in 30 districts in the state of
Assam. At least 3,024 villages in the affected districts continued to be underwater and
44,08,142 people are hit in several districts. Notably, in this wave of floods, 2400
endangered species of Indian rhinoceros in Kaziranga National Park were badly
affected.
 2020 Assam floods: Initial flooding started in May 2020 due to heavy rainfall
affecting 30,000 and destroying crops across 5 districts. As of October 2020 the
floods affected over five million people, claiming the lives of 123 people, with an
additional 26 deaths due to landslides, 5474 villages were affected and over one
hundred and fifty thousand people found refuge in relief camps.
 2020 Hyderabad floods: The 2020 Hyderabad floods were a series of floods associated
with Deep Depression BOB 02 that caused extensive damage and loss of life as a
result of flash flooding in Hyderabad, India in October 2020. The fourth tropical
cyclone and third deep depression of the 2020 North Indian Ocean cyclone season,
BOB 02 formed on 11 October over the west-central Bay of Bengal and slowly drifted
towards the east coast of India over the following three days.
 2021 Uttarakhand flood: The 2021 Uttarakhand flood, also known as the Chamoli
disaster, began on 7 February 2021 in the environs of the Nanda Devi National Park, a
UNESCO World Heritage Site in the outer Garhwal Himalayas in Uttarakhand state. It
was caused by a large rock and ice avalanche consisting of material dislodged from
Ronti peak. It caused flooding in the Chamoli district, most notably in the Rishiganga
river, the Dhauliganga river, and in turn the Alaknanda—the major headstream of the
Ganges. The disaster left over 200 killed or missing. Most were workers at the
Tapovan dam site.

14.  2021 Maharashtra floods: A series of floods took place across the Indian state of
Maharashtra in 2021. As of 28 July 2021, around 251 people had died and over 100
were still missing due to floods and landslides. Thirteen districts have been affected in
western Maharashtra. The flood was part of a series of tightly clustered extreme
weather events in July 2021, including extreme rain events in Henan, China and
Europe and is part of an increase in rain events during the Indian monsoon season
caused by climate change.
Prevention and Mitigation measures of floods in India.
Prevention – encompasses activities designed to provide permanent protection from
disasters. It includes engineering and other physical protective measures, and also legislative
measures controlling land use and urban planning.
Humans cannot stop the rains from falling or stop flowing surface water from bursting its
banks. These are natural events, but we can do something to prevent them from having a
great impact. Here are a few –

15. Sea / Coastal Defence Walls
Sea walls and tide gates have been built in some places to prevent tidal waves from pushing
the waters up ashore. In some areas too, sandbags are made and placed in strategic areas to
retain floodwaters.
Retaining walls
In some places, retaining walls levees, lakes, dams, reservoirs, or retention ponds have been
constructed to hold extra water during times of flooding.
Town planning
Builders must acquire permission before buildings are erected. That will ensure that
waterways are not blocked. Also, drainage systems must be covered and kept free from
objects that chock them. This way, water can quickly run through if it rains and minimizes
any chance of town flooding. Drainage systems should also be covered to prevent litter from
getting into them.
Vegetation
Trees, shrubs, and grass help protect the land from erosion by moving water. People in low-
lying areas must be encouraged to use a lot of vegetation to help break the power of moving
flood water and also help reduce erosion.
Education
In many developing countries, drainage systems are chocked with litter and people have little
knowledge of the effects that can have during rain. When it rains, waterways and culverts are
blocked by massive chunks of litter and debris, and water finds its way into the streets and
people’s homes. Education is therefore very important, to inform and caution people about
the dangers of floods, what causes floods, and what can be done to minimize its impact.
Detention basin
These are small reservoirs built and connected to waterways. They provide temporary
storage for floodwaters. This means in an event of flooding, water is drained into the basin
first, giving people more time to evacuate. It can also reduce the magnitude of downstream
flooding.

16. The flood mitigation measures may be classified into structural and non-structural
measures. The structural measures are physical in nature and aim to prevent flood waters
from reaching potential damage areas, whereas non-structural measures strive to keep the
people away from flood waters.
Non-structural measures for flood mitigation
Non-structural measures strive to keep people away from flood waters. These measures
allow the use of flood plains judiciously by reducing the disaster dimension, while retaining
its beneficial effects
Rain Water Harvesting for flood mitigation
Rainwater Harvesting is employed in flood mitigation in rain-drenched countries, and in
solving infiltration problems of sealed surfaces in urban areas and industrial complexes, or in
avoiding polluted water and toxic ground water. Mostly, RWH is environmentally sound as
it assists in recharging ground water, enhances wetlands, forest conservation, encourages
ecological farming, and slows down construction of new dams for water supply thus helping
the ecological flow.

17. River basin management for flood mitigation
River Basin Management includes all aspects of Hydrology, Ecology, Environmental
Management, Wetlands and Flood Plains. River Basin Management deals with technical, as
well as socio-economic and ecological aspects and calls for an integrated approach. This
approach consists of a comprehensive set of analysis steps, supported by mathematical tools
for the analysis of natural resource systems in a socio-economic context.
Resilient structures for flood mitigation
Flood resilient structures are such structures that can recover from a flood in less time with
reduced damage to the property. This does not prevent the flood from entering a building but
controls the possible damage that can result from flooding. As part of this approach, the form
of buildings, their occupation and use of materials will need to consider the range of flood
conditions to which they may be exposed.

18. Bibliography
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