Flood & Cyclone – Cause & Mitigation Measures

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General concepts of Disaster Management, Cause of flood in West Bengal, General flood mitigation strategies, Formation of Cyclone, Mitigation.


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Flood & Cyclone – Cause & Mitigation Measures:

Flood & Cyclone – Cause & Mitigation Measures Suvajit Singha Disaster Management Officer Directorate of Disaster Management, W.B .

An overview:

An overview

Disaster Risk Reduction agenda in progress : :

Disaster Risk Reduction agenda in progress : Prior to 1990s – Focus on Civil Defence , Relief organizations, humanitarian response to emergencies During 1990s – International Decade on Natural Disaster Reduction (IDNDR), Yokohama Strategy which also considered linkage between disasters & development Since 2000 – International Strategy for Disaster Reduction (ISDR): reduce disaster risk Hyogo Framework: 2005-2015 – Building the resilience of nations & communities to disasters as part of Sustainable Development shared with the Humanitarian agenda REACTIVE PROACTIVE

ISDR (International Strategies for Disaster Reduction):

ISDR (International Strategies for Disaster Reduction) Created in December 1999, UNISDR is the secretariat of the International Strategy for Disaster Reduction (ISDR). It is the successor to the secretariat of the International Decade for Natural Disaster Reduction with the purpose of ensuring the implementation of the International Strategy for Disaster Reduction (General Assembly (GA) resolution 54/219).

ISDR –contd……:

ISDR – contd …… The mandate of UNISDR expanded in 2001 to serve as the focal point in the United Nations system for the coordination of disaster reduction and to ensure synergies among the disaster reduction activities of the United Nations system and regional organizations and activities in socio-economic and humanitarian fields (GA resolution 56/195). This was in response to a need for mainstreaming disaster risk reduction within the development and other areas of work of the UN.

HFA (Hyogo Framework for Action-2005):

HFA (Hyogo Framework for Action-2005) "Hyogo Framework for Action 2005-2015: Building the Resilience of Nations and Communities to Disasters" was adopted by the World Conference on Disaster Reduction, held in Kobe, Hyogo, Japan, in January 2005 by 168 countries. It is the first plan to explain, describe and detail the work that is required from all different sectors and actors to reduce disaster losses.

HFA- contd….:

HFA - contd …. Priority Action 1: Ensure that disaster risk reduction is a national and a local priority with a strong institutional basis for implementation. Priority Action 2: Identify, assess and monitor disaster risks and enhance early warning. Priority Action 3: Use knowledge, innovation and education to build a culture of safety and resilience at all levels. Priority Action 4: Reduce the underlying risk factors. Priority Action 5: Strengthen disaster preparedness for effective response at all levels.

What is Disaster ?:

What is Disaster ? The term disaster owes its origin to the French word “ Desastre ” which is a combination of two words ‘des’ meaning bad and ‘aster’ meaning star. Thus the term refers to ‘Bad or Evil star’. A disaster can be defined as “A serious disruption in the functioning of the community or a society causing wide spread material, economic , social or environmental losses which exceed the ability of the affected society to cope using its own resources”.

What is Hazard ?:

What is Hazard ? Hazard may be defined as “a dangerous condition or event, that threat or have the potential for causing injury to life or damage to property or the environment.” The word ‘hazard’ owes its origin to the word ‘ hasard ’ in old French and ‘ az-zahr ’ in Arabic meaning ‘chance’ or ‘luck’.

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Types Hazards Geological Hazards 1. Earthquake 2. Tsunami 3. Volcanic eruption 4. Landslide 5. Dam burst 6. Mine Fire Water & Climatic Hazards 1. Tropical Cyclone 2. Tornado and Hurricane 3. Floods 4. Drought 5. Hailstorm 6. Cloudburst 7. Landslide 8. Heat & Cold wave 9. Snow Avalanche 10.Sea erosion Environmental Hazards 1. Environmental pollutions 2. Deforestation 3. Desertification 4. Pest Infection Biological 1. Human / Animal Epidemics 2. Pest attacks 3. Food poisoning 4. Weapons of Mass Destruction Chemical, Industrial and Nuclear Accidents 1. Chemical disasters 2. Industrial disasters 3. Oil spills/Fires 4. Nuclear Accident related 1. Boat / Road / Train accidents / air crash Rural / Urban fires Bomb /serial bomb blasts 2. Forest fires 3. Building collapse 4. Electric Accidents 5. Festival related disasters 6. Mine flooding

What is vulnerability ? :

What is vulnerability ? Vulnerability may be defined as “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.”

What is capacity ? :

What is capacity ? Capacity can be defined as “resources, means and strengths which exist in households and communities and which enable them to cope with, withstand, prepare for, prevent, mitigate or quickly recover from a disaster”.

What is risk ? :

What is risk ? Risk is a “measure of the expected losses due to a hazard event occurring in a given area over a specific time period. Risk is a function of the probability of particular hazardous event and the losses each would cause.” The level of risk depends upon: Nature of the hazard Vulnerability of the elements which are affected Economic value of those elements

Disaster Crunch Model :

Disaster Crunch Model x = Disaster Risk Hazard Vulnerability Capacity

The Indian Context : :

The Indian Context : 1.2 billion people still growing at 1.5% per annum 300 million people live below poverty line More than 50% malnourished 39% people above 15 are illiterate More than 7000km are coastline Diverse community (multi lingual/multi ethnic multi religious) Unplanned urban growth(4.5% per annum)

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HAZARD PRONENESS OF WEST BENGAL No other State except WB in India has all of the following natural hazards, viz . Flood 7. Erosion Cyclone 8. Fire Hailstorm/ Kalbaishakhi 9. Tsunami Earthquake 10. Cloud Burst Landslide 11 Pest Attack Drought

What is Flood ?:

What is Flood ? Flood is an overflow of water, an expanse of water submerging land (Wikipedia) “An overflowing of water onto land that is normally dry” (Oxford Dictionary) “A general and temporary condition of partial or complete inundation of two or more acre of normally dry land area” (National flood insurance agency, USA) “A relatively high flow of water that overtops the natural or artificial banks and comes in conflict with man” ( Jha , R. 1993)

Birbhum Dist. Map:

Birbhum Dist. Map

Birbhum District – Rivers :

Birbhum District – Rivers

Flood – Introduction ::

Flood – Introduction : The degree of a flood hazard is dependent on the factors such as depth and velocity of water, the duration of flood, and the load (sediment, salts, sewage, and chemicals) carried. The vulnerable landscapes for flood include the low-lying parts of floodplains, low-lying coasts and deltas, small basins subject to flash floods, areas below unsafe or inadequate dams, and alluvial fan. • Floods may be of two types: 1) River flood resulting from rainfall, snowmelt, ice-jam, landslide, dam failure, etc. 2) Coastal flood resulting from storm surges and tsunami.


FLOOD TYPES (OCCURRENCE DUE TO HEAVY RAINFALL) Flash floods associated with violent, convection storms of a short duration. Result of heavy rainfall of short duration falling over a small area known to wash away roads and bridges, damage houses. Riverine floods occurs in the valley of a large river with tributaries. Flooding develops from rainfall lasting for hrs, sometimes days and covering wide area of watershed. In summer due to cyclones & slow moving depressions. Multiple event flood Heavy rainfall by successive weather disturbances follow each other e.g . floods in the Indo- Gangetic plains & Central India regions.

Floods- Primary Causes : :

Floods- Primary Causes : Environmental Topography , soil characteristics, vegetation cover, impervious covered area Inadequate drainage system and lack of their maintenance Flat river gradients Meteorological Cloud bursts Short duration intense rainfall Cyclonic storms- heavy downpour with very high wind velocities Climate change Increase in extreme rainfall events High snow and glacier melt Breach of the embankments, dams etc.

Floods- Secondary Causes : :

Floods- Secondary Causes : High tides Siltation in river channels Increased urbanisation due to migration of people to urban areas Encroachment of flood plains Haphazard and unplanned growth of urban areas

Recent Increase in Floods :

Recent Increase in Floods Apparent increased turbulence in the climate (Climate Variability) owing to global warming Land degradation in up-streams catchments Deforestation leading to loss of natural storage in vegetation and soil Land use changes down streams Increased pressure on natural floodplain from rapidly expanding urban and industrial areas


FLOOD SCENARIO North 24 Parganas South 24 Parganas Calcutta Puruliya Hugli li Darjiling Jalpaiguri Uttar Dinajpur Dakshin Dinajpur WEST BENGAL East Medinipur Birbhum Barddhaman Murshidabad Maldah Haora West Medinipur Bankura Koch Bihar Flood No flood Nadia


CAUSES OF FLOOD IN WEST BENGAL : Sudden release of water from the reservoirs located in Jharkhand Heavy rainfall in the upper catchments of the rivers originating in Sikkim, Bhutan and coming through Bihar Shallow river bed Synchronization of tide with discharge of flood water Spilling of Bhagirathi, Ajay & Damodar due to inadequate capacity of rivers and tidal effects


RIVER BASINS : Three river basins---- Ganga , Brammhaputra & Subarnarekha The area-wise distribution of the above basins in the State : 1. Brahmaputra Basin 11,860 Sq. Km. 2. Ganga Basin including Sundarban Area 74,732 Sq. Km. 3. Subarnarekha Basin 2,160 Sq. Km. These three main river basins are divided into Sub- basins having individual catchment of their own.

Records of large FLOODS in West Bengal :

Records of large FLOODS in West Bengal Period Description 1978 Major flood; Affected 235 blocks in Midnapore , Howrah Hooghly Murshidabad , Nadia, 24 Parganas , Bankura , Burdwan , Birbhum , Malda , Puruliya , Human Life lost: 1370, House Damaged 1361338; Population Affected: 156.25 lakhs 11/07/1999–03/08/1999 Flooding due to monsoonal rains 24/10/1999–12/11/1999 Tropical cyclones caused destruction of an estimated number of 1500 villages. Floods due to brief torrential rains affected areas of Kolkata, Burdwan and Birbhum

Records of large FLOODS in West Bengal :

Records of large FLOODS in West Bengal Period Description 02/08/2000–01/10/2000 Besides flash floods triggered by incessant torrential storms, disaster is also accredited to the opening of sluice gates of dams. The fatalities counted to the tune of 1262, besides affecting millions of people 21/06/2002–28/08/2002 Flooding in and Jalpaiguri in north due to monsoonal rains. Flash floods swamped ten villages, causing four deaths and 11,000 displacements 11/06/2003–10/10/2003 Monsoonal rains caused floods affecting the regions of , Jalpaiguri , Malda and Murshidabad

Records of large FLOODS in West Bengal :

Records of large FLOODS in West Bengal Period Description 24/06/2006–03/08/2006 The regions of Birbhum , Burdwan and Murshidabad were affected mainly from continuous monsoonal downpour 18/09/2006–05/10/2006 Monsoonal rains and tropical cyclone-driven storms in the hit and . recorded 50 deaths, 300 were injured and 30,000 mud houses destroyed. Heavy rains left large parts of Kolkata city under water; subsequently 2000 people were evacuated from the city 03/07/2007–22/09/2007 The hazard affected Kolkata and several other districts. Eighty-three deaths were reported, and millions of people were marooned in 3000 villages in coastal areas of the state 22/09/2007–08/10/2007 Heavy rain from tropical depression in the caused flooding leading to 51 deaths, and affecting 3.2 million people

Flood Management::

Flood Management: Some measures can be to reduce the impact of the flood hazard adopted are as follows: Adoption of sustainable flood management techniques : Sustainable flood management provides the maximum possible social and economic resilience against flooding, by protecting and working with the environment, in a way which is fair and affordable both now and in the future.

Flood Mitigation ::

Flood Mitigation : Flood forecasting : With reliable advance information/warning about impending floods loss can be reduced to a considerable extent Flood inundation mapping & land use planning: Satellite R. S. is extremely useful in monitoring the dynamics of water spread Flood plain zoning: Means categorization based on admin. , Legislations for planning & dev. of flood plains for various purposes.

Flood Mitigation ::

Flood Mitigation : Flood insurance: Scheme of charging insurance premiums based on nature & location of establishment in flood plains Decision support system for real time flood warning & management: based on database linked to math. Models based on hydro-meteorological information

Flood Mitigation ::

Flood Mitigation : Increase in the provision for flood hazard management in the Five Year Plans and their equitable distribution among people irrespective of caste, religion, political colour etc. • Implementation of proper land use planning, generating forest cover and reducing surface run-off, and imposing restrictions on improper land uses. Arrest desertification and deforestation to reduce flash flood. Speedy constructions of concrete embankments along the coast to arrest the ingress of storm surge water

Recommendations ::

Recommendations : Flood mitigation approach should be adopted during the planning & design stage. Policy instruments e.g. guidelines for flood prevention criteria should be in public domain. Training of officials, builders, planners & architects on urban flood management. Measures to improve & maintain drainage channels & water storage areas by RWH (Rain water Harvesting) must be considered in increased population growth.

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Are we Prepared?

What is a Cyclone?:

What is a Cyclone? Cyclones are rotating, intense low pressure systems that develop in the oceanic area surrounding Indian Sub- continent. Tropical cyclones are the bane of the warm oceans. Cyclones occur due to a combination of warm sea temperature, high relative humidity and atmospheric instability . In the northern hemisphere it will rotate clockwise and in the southern hemisphere is will rotate counter-clockwise

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Typhoons in the North West Pacific Hurricanes in the Caribbean, United States and parts of Pacific Tropical cyclones in India Willie-Willie in Australia Cyclones are global phenomena and go by many names :

International Classifications of Storms:

International Classifications of Storms Low Pressure systems Wind Speed in Kms. per hour Depression 36 – 55 Deep Depression 56 – 66 Cyclone 67 – 96 Severe Cyclone 96 – 117 Super Cyclone > 117

Tropical Cyclone Hazard Database:

Tropical Cyclone Hazard Database Year Location Name Death 1990 Philippines Typhoon Mike 748 1990 India Unnamed Cyclone 967 1991 Bangladesh Unnamed Cyclone 140,000 1991 Philippines Tropical Storm Thelma 6,000 1992 United States Hurricane Andrew 40 1993 Fiji Cyclone Kina 30 1994 Bangladesh Unnamed Cyclone 400 1994 China Typhoon Fred 1,126 1994 Madagascar Cyclone Geraldo 300 1994 Haiti Hurricane Gordon 800 1995 Philippines Typhoon Angela 800 1999 India Unnamed Cyclone 10,000 2009 India Cyclone Aila 197

Some General Know How ::

Some General Know How : Between 80 to 100 tropical cyclones occur around the world every year. Cyclones vary on frequency in various parts of the world. The 7516.6 kms long Indian coastline is the earth’s most cyclone battered stretch of the world. The state which are affected by cyclones in the Bay of Bengal are – West Bengal, Orissa, AP, Tamil Nadu and Kerela . Along the Arabian sea coast are:- Gujarat, Maharastra , Goa, Karnataka and Kerela About 2/3 of the cyclones that occur in the Indian coastline occur in the Bay of Bengal.

Stages of a cyclone::

Stages of a cyclone: The development of a tropical cyclone can be divided into three stages Formation and Initial development stage Full maturity and Modification or Decay Depending on their tracks over the warm tropical seas and proximity to land, they may last for less than 24 hours to more than three weeks (the average duration is around six days)

Formation of a cyclone Four atmospheric and oceanic conditions are necessary for the development of a cyclonic storm::

Formation of a cyclone Four atmospheric and oceanic conditions are necessary for the development of a cyclonic storm: A warm sea temperature in excess of 26 degree centigrade, to a depth of 60 m, which provides abundant water vapour in the air by evaporation. High Relative humidity (degree to which the air is saturated by water vapor) of the atmosphere to a height of about 7000 m facilitates condensation of water vapor into water droplets and clouds, releases heat energy and induces drop into pressure

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Atmospheric instability (an above average decrease of temperature with altitude) encourages considerable vertical cumulus cloud convection when condensation of rising air occurs. A location of at least 4-5 latitude degrees from the Equator allow the influence of the force due to the earth’s rotation ( Coriolis force) to take effect in inducing cyclonic wind circulation around low pressure centers.

Track of Cyclone Aila ::

Track of Cyclone Aila :

Formation of Cyclone Aila ::

Formation of Cyclone Aila : Initial Stage Deep depression

Formation of Cyclone Aila : contd…:

Formation of Cyclone Aila : contd … Cyclonic Storm Severe cyclonic storm

Formation of Cyclone Aila : contd…:

Formation of Cyclone Aila : contd … Prior to Landfall During Landfall

“Eye” of a Cyclone : :

“Eye” of a Cyclone : The most striking feature of a cyclone is its ' eye ' . The eye can be seen clearly in satellite pictures in the case of a well-developed cyclone. The eye is small and almost circular; it coincides with the area of lowest pressure and has a diameter ranging from 8 km to 50 km. The eye is warmer than the rest of the storm area. The more violent the storm, the warmer the eye. The winds are very light in the eye, usually not more than 25 to 30 km/hr and rain is practically absent. In contrast, the strongest winds and the heaviest rain occur just outside this central eye.

“Eye” of a Cyclone ::

“Eye” of a Cyclone : Eye


WIND & CYCLONE ZONES of WEST BENGAL West Bengal has two cyclone seasons : Pre-monsoon- April-May, Post-monsoon- Nov-Dec, Pre-monsoon cyclones are less dangerous compared to post-monsoon cyclones Average number of depressions formed over the Bay of Bengal every year resulting into cyclone: Pre-monsoon-11 Post-monsoon-28 West Bengal has three wind & cyclone zones : very high wind & cyclone risk zone ( Vb = 50m/s) high wind & cyclone risk zone ( Vb = 47m/s) moderate wind & cyclone risk zone ( Vb = 39m/s)


IMPACT AREA OF CYCLONE : WHOLE OF WEST BENGAL, SEVERELY AFFECTED AREAS ARE Coastal districts: South 24 Parganas , North 24 Parganas , Purba Medinipur and Paschim Medinipur , Riparian districts: Howrah, Hooghly and Murshidabad , Hinterland districts: Nadia, Burdwan and Kolkata metropolis. PHYSICAL & DEMOGRAPHIC VULNERABILITY TO CYCLONE: Total Area (Sq. Kms ) No. of districts No. of mouzas Population 49,211.00 10 24,190 5.9 Crores (app.)


Storms surge is the most destructive phenomena associated with a cyclone, particularly in the coastal and riparian areas, Uprooting of trees, telegraphic poles, communication towers, disruption of transport linkages, Loss of life - both human and livestock, Damage of public and private property, river and coastal embankments, etc., Agricultural damage : standing crop, orchards, salination of agricultural land. LOSSES SUFFERED DURING 2000-06: EFFECTS OF CYCLONE AND HIGH VELOCITY WIND : No. of human lives lost No. of cattle lost Crop area affected (hectare) Loss in production(MT) Loss in money value(in Lakh) 92 50 1,71,865.20 19,86,582.00 52,278.473

Cyclone Warning System in India:

Cyclone Warning System in India Indian Meteorological Department is the Nodal Agency for wind detection, tracking and forecasting cyclones. Cyclone tracking is done through INSAT satellite at 12 detection radars in India.

Warning Dissemination:

Warning Dissemination Warning is Disseminated by the following means: - High Priority Telegram - Doordarshan - All India Radio - Bulletins in the Press - Satellite Based disaster Warning Systems - Teleprint - Telex - Telephone - Government Channel

Cyclone Warning is Disseminated to::

Cyclone Warning is Disseminated to: Community Port Authorities Fisheries Department Commercial Aviation Officer of Central and State Government General Public

Cyclone Preparedness:

Cyclone Preparedness Preparedness can be at three levels: Individual Community and Government level (in Pre, During and Post Disaster)

Individual Preparedness in Pre-Disaster season ::

Individual Preparedness in Pre-Disaster season : Listen to the weather report in radio/TV and if possible disseminate the information to the local people Store adequate food grains, water medicines, kerosene, lantern, matchbox, dry cell Keep important papers in the emergency kit Keep doors and windows locked and if damaged get it repaired Make sure that proper diet is carried for children and old people Keep the list of important address and phone number like police, Block Development officer, relatives residing outside that particular place Conduct mock drill for yourself Be calm

Individual Preparedness During a Disaster:

Individual Preparedness During a Disaster Listen to the radio/ community warning system for further details Close all doors and windows and stay indoors Paste papers on the glass windows to prevent splints flying into the house Keep food items and cloths in water proof bags Don’t venture into the sea Wear warm cloths for protection Avoid being misled by rumors. Disseminate information that is only official Stay away from low lying areas, electric poles, trees Switch off all electrical appliances

Individual Preparedness in Post Disaster ::

Individual Preparedness in Post Disaster : Don’t move out until officially informed Use the recommended route for returning Check whether there is a gas leak before using the stove Dry electrical appliances thoroughly before use Get oneself inoculated against diseases immediately at the nearest hospitals and seek medical care Be careful of snake bites All debris should be cleared Damage assessment to be done

Develop a plan : :

Develop a plan : Knowledge about the hazards that could affect your family. Know your home's vulnerability to storm surge , flooding and wind . Locate a safe room or the safest areas in your home for each hurricane hazard. Determine escape routes from your home and places to meet. Have an out-of-state friend as a family contact. Make a plan now for what to do with your domestic animal.

Develop a plan (cont….) :

Develop a plan (cont….) Post emergency telephone number. Check your insurance coverage. Stock non-perishable emergency supplies. Take First Aid kit, disaster preparedness classes. Take Radio.

What to do: :

What to do : Building cyclone shelters Coastal green-belt project for afforestation (In Sunderban , conserve mangrove trees) The improved cyclone warning system Mobilisation of people before the impending cyclones have been very effective in minimising the death toll.

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