GNR 639 : Natural Disaster And Management Atmosphere - Meteorology - - PowerPoint PPT Presentation

Atmosphere - Meteorology disasters Blizzards Cyclonic storms Droughts Thunder storms Hailstorms Heat waves Tornadoes

GNR 639 : Natural Disaster And Management

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Lesson 7 Storm & Cyclone

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Lightning is an atmospheric discharge of electricity accompanied by thunder, which typically

• ccurs during thunderstorms and sometimes during volcanic eruptions or dust storms. In the

atmospheric electrical discharge, a leader of a bolt of lightning can travel at speeds of 220,000 km/h, and can reach temperatures approaching 30,000°C. Hail is a form of solid precipitation which consists of irregular lumps of ice, that are individually called hail stones. It consists of water ice and measuring in size between 5 mm and 150 mm in diameter, with the larger stones coming from severe thunderstorms. It has caused serious damage to automobiles, aircraft, skylights, glass-roofed structures, livestock, and crops (sensitive crops such as Wheat, corn, soybeans and tobacco). Blizzards are severe winter storms characterized by low temperature, strong winds, and heavy

• snow. The difference between a blizzard and a snow storm is the strength of the wind. The

storm must have winds exceeding of 35 miles per hour and reduced visibility to 1/4 miles. 7.02

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Hurricanes bring intense wind, torrential rain, high waves, strong currents, flooding, storm surge, tornadoes, landslides, and coastal erosion. They are revolving storms

• riginating near the equator that are accompanied by torrential rain and wind speeds

exceeding 74 mph. In the Atlantic and eastern Pacific, including Hawaii, these whirling storms are called

• hurricanes. In the western Pacific, including East Asia and Australia, they are typhoons.

In the Indian Ocean, they are cyclones. Saffir-Simpson Hurricane Scale expresses a hurricane’s strength by its sustained wind speed—Category 1: 74-95 mph; Category 2: 96-110 mph; Category 3: 111-130 mph; Category 4: 131-155 mph; Category 5: in excess of 155 mph.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Tornado is a violently rotating column of air that is in contact with the ground, either pendant from underneath a cumuliform cloud visible as a funnel cloud. For a vortex to be classified as a tornado, it must be in contact with both the ground and the cloud base. The causes of Tornadoes are - 1. Tornadoes are formed when hot air and cold air are mixed. 2. The clouds grow larger and

• larger. Finally, a thunderstorm is brewed up with a strong updraft.3. The

moisture in the warm air rises and condenses into large clouds.

Tornado scale Wind speed (km/h) Damages F1 73-115 Light - broken tree branches and some damage to chimneys F2 116-180 Considerable - roofs flown of houses and cars lifted slightly F3 181-250 Severe - walls damaged, cars fully lifted and most trees uprooted F4 251-330 Devastating - cars and badly constructed houses thrown around F5 – Twister 331-415 Incredible - strong frame houses leveled off foundations and swept away, automobile-sized missiles fly away in excess of 100 meters F6 Super Twister 416-510 Inconceivable - top end of F5 category

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

(Source courtesy: thinglink.com) (Source courtesy: whyflies.org)

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Scale Wind speed km/hr Central pressure (mb) Damage 1 120-150 > 980

Damage to trees, foliage & poorly anchored mobile homes. Storm surge 1.2-1.5 m above

• normal. Flooding of low-lying areas & roads. Limited damage to piers & small crafts.

2 151-175 965-979

Broken & foliage-stripped trees. Major damage to mobile / light roofed homes. Storm surge 1.6-2.4 m. Flooding of coastal roads & areas prior (2-4 hrs) to arrival of storm. Piers suffer extensive damage and unprotected vessels are torn off.

3 175-210 945-964

Foliage stripped from trees blown down. Great damage to roofing material, door and

• windows. Structural damage to small buildings. Storm surge 2.5-3.6 m. Serious coastal area

flooding (3-5 hrs before storm) and damage to buildings on coast. Flooding of areas above 2

• r 3m above msl as far as 13 km.

4 211-250 920-944

Shrubbs, tree and signs are blown down. Extensive damage roofing material and ripping off

• roofs. Destroyed mobile & light structures. Storm surge 3.7-5.5 m. Flooding of areas 3 to 4 m

above msl, 4 to 6 hrs prior storm. Beaches suffer erosion, scouring and evacuation of homes upto 500m.

5 >250 < 920

Total damage. Shattered window glasses & structures blown away. Storm surge > 5.5 m. Lower floors of structures flooded heavily.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

A dust / sand storm is a meteorological phenomenon common in arid and semi- arid regions. It arises when strong wind blows loose sand and dust from a dry

• surface. It is caused by droughts and poor farming and grazing practices also

from extensive deforestation and desertification in many regions. They carry not

• nly nutrients but also microbes and pollens.

Source courtesy: crystallinks.com

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

A tropical cyclone is a storm system characterized by a large low-pressure at the center with numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor contained in the moist air. The term cyclone refers to cyclonic storms' with anticlockwise rotation in the Northern Hemisphere and clockwise rotation in the Southern Hemisphere. They are known around the world by various names: hurricanes in the Atlantic and Caribbean, typhoons in the West Pacific, Baguios in the Philippines, Cordonazos in Mexico, Tainos in Haiti. It is defined as a circular storm with rotating wind speed exceeding 64 knots (32 m/sec). Life span of a tropical cyclone is, on average, about six to nine days until it enters land or re-curves into temperate latitudes.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Super cyclone - When the maximum sustained 3 minutes surface winds are more than 119 knots, the low pressure system is called as Super Cyclone over north Indian Ocean. Eye and center - A strong tropical cyclone will harbor over large area of strong sinking air at the center of circulation, develop into a eye of the storm. Weather in the eye is normally calm and free of clouds, irrespective of extremely violent sea surface. Central Dense Overcast (CDO) is the concentrated area of strong thunderstorm activity near the center of a tropical cyclone; in weaker tropical cyclones, the CDO may cover the center completely. If the radius is less than two degrees of latitude or 222 km, then the cyclone is "very small"

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Satellite image showing 1999 Orissa Super Cyclone (Courtesy: Indian Meteorology Department)

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Source courtesy: pnnl.gov Source courtesy: thewatchers.adorraeli.com

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Source courtesy: geofffox.com

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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• 1. Location Specific forecast (3 days - 3 hourly interval)
• 2. Coastal forecast (7 days - 3 hourly interval)
• 3. Regional forecast (7 days - 3 hourly interval)
• 4. Indian Ocean forecast (5 days - 6 hourly interval)
• 5. Global forecast (5 days - 6 hourly interval)
• 6. Value added services

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Major basins and related warning centers - There are six Regional Specialized Meteorological Centers (RSMCs) designated by the World Meteorological Organization and are responsible for tracking and issuing bulletins, warnings, and advisories about tropical cyclones in their designated areas of responsibility.

Basin Beginning & end of season Tropical storm (>34 knot) Tropical cyclone (> 63 knots) Category 3 + TCs (> 95knot) North Atlantic June to November 10.6 5.9 2.0 South Indian November to April 20.6 10.3 4.3 Northeast Pacific May to November 16.3 9.0 4.1 Northwest Pacific January to April 26.7 16.9 8.5 Australia-Southwest Pacific November to April 9 4.8 1.9 North India April to December 5.4 2.2 6.2

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Global Cyclone Basin and operational agencies 1-North Atlantic (National Hurricane center, USA), 2.North eastern pacific (National Hurricane center, USA), 3. North Central Pacific (Central Pacific Hurricane Centre USA) 4. North west Pacific (Japan Meteorological Agency), 5. North Indian (IMD), 6. South West India, 7. South Pacific (Fuji Meteorological Service) and 8. Australian region (Bureau of Meteorology & Indonesian meteorological and Geophysical Agency) (Courtesy: sott.net )

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Formation of tropical cyclones depends on 1) water temperatures of at least 26.5° are needed down to a depth of at least 50 m and waters in this temperature cause the overlying atmosphere to be unstable enough to sustain convection and thunderstorms. 2) Rapid cooling with height, allows the release of the heat of condensation that powers a tropical cyclone. 3) High humidity is needed in the lower-to-mid troposphere are more favorable for disturbances to develop. 4) Low amounts of wind shear are needed, as high shear is disruptive to the storm's circulation. 5) Tropical cyclones need to be more than 555 km or 50C of latitude away from the equator, allowing the Coriollis effect to deflect winds blowing towards the low pressure center and creating a circulation. 6) Formative tropical cyclone needs a pre-existing system of disturbed weather. Landfall is when the center of storm’s circulation crosses the coastline. Storm conditions may be experienced on the coast and inland before landfall. A tropical cyclone can launch its strongest winds over land and not able to make a landfall is said to be a direct hit of the storm on the coast. 7.19

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Impacts Storm Surges are positive or negative changes in sea level resulting from variations in atmospheric pressure and associated winds. Water inundates low lying areas of the coastal regions causing heavy floods, erosion

• f beaches and embankments, damage to vegetation and reducing soil fertility.

Flooding due to storm surges pollute drinking surface water sources resulting in shortage of drinking water and causing out-break of epidemics, mostly water borne diseases Very strong Gales cause uprooting of trees, damage to dwellings, overhead installations, communication lines etc., resulting in loss of life and property.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

On Land Structures Agriculture Trees High winds Damages buildings, power lines, towers Damage to standing crops such as grains Widespread loss of timber Flooding losses Damage structures Damage to standing crops in flood areas Minor Flooding (storm surges) Extensive damage to roads, structures, etc. Extensive damage to crops, irrigation systems, leaves harmful salt deposits, scours topsoil, contaminates wells Loss of trees System Pressure deficient hPa Associated wind speed Knots (Kmph) Low pressure area 1.0 <17(<32) Depression 1.0- 3.0 17-27 (32–50) Deep Depression 3.0 - 4.5 28-33 (51–59) Cyclonic Storm 4.5- 8.5 34-47 (60-90) Severe Cyclonic Storm SCS) 8.5-15.5 48-63 (90-119) Very Severe Cyclonic Storm 15.5-65.6 64-119 (119-220) Super Cyclonic Storm >65.6 >119(>220)

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( Courtesy: United Nations Development Program)

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Forecast Various Techniques used for Track Prediction of the storm: 1) Methods based on climatology, persistence and both Climatology & Persistence (CLIPER); 2) Synoptic Techniques - Empirical Techniques ; 3) Satellite Techniques ; 4) Statistical Techniques using climatologies, Persistance and synoptic; 5) Analogue Techniques 6) Numerical weather prediction models. Probability of correct forecast decreases with increasing forecast validity period. Mean forecast errors for 12, 24, 48 and 72 hours are about 50, 140, 300 and 500 km respectively,

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Forecast Strategy includes collection of observations with enhanced collection in the cyclone vicinity; specialized analysis methods and the preparation of forecasts using the most appropriate techniques for the situation. Warning Strategy is an explicit understanding of the forecast uncertainties; an appreciation of the most vulnerable and susceptible communities in the potential warning area, the "least regret" approach to ensuring no catastrophes occur; and a sharp sense of timeliness to fit with communication capacities and community cycles. Response Strategy includes public education and awareness programs aimed at ensuring good community responses; developing an infrastructure capable of handling the threat; ensuring a balanced preparation appropriate to the community under threat, to ensure full response without unnecessary

• ver-reaction; taking contingency action, such as establishing emergency operations

Vulnerability Physical vulnerability maps

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Cyclones disrupt agriculture and destroy crops.

• High winds destroy some standing crops, especially grains, and damage orchards and forests.
• Flooding from intense rains damages certain crops, especially tubers, and may cause excessive

erosion.

• Storm surges scour and erode topsoils, deposit salts on fields, and may increase salinity in

subsurface water.

• Access to markets for buying and selling agricultural produce may be impeded by damage to

roads, bridges, railways, etc.

• Cost of relief and reconstruction creates a financial burden on the government.
• Increased expenditures for preventive and curative medicine, aid to the unemployed, and repair
• r replacement of housing are required,
• Decrease in public resources due to an overall decrease in economic activity and tax receipts.

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Principles of Hazard Warnings

1) Design messages to attract attention and evoke timely rational response; 2) Specify the nature, severity and imminence of the threat, in accord with relevant promulgated warning stages

• r phases;

3) Specify the location of threatened areas with reference to well-known geographical locations or landmarks; 4) Advise optimum avoidance or preparedness measures related to the degree and imminence of the threat; 5) Achieve a balance in content between detail and simplicity in terms meaningful to the majority of recipients; 6) Allocate the highest priority to the more critical elements in messages, especially those requiring urgent responsive action; 7) Increase frequency of issue or updates as the threat increases (warnings are perishable products); 8) Take into account pre-event behavioral response studies, the level of community experience, and the vulnerability of threatened areas; 9) Advise how, when and where to obtain further information.

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4-stage warning system for Tropical Cyclones?

(1) Pre-Cyclone Watch - Issued when a depression forms over the Bay of Bengal irrespective of its distance from the coast and is likely to affect Indian coast in future. The pre-cyclone watch is issued by the name of Director General of Meteorology and is issued at least 72 hours in advance

• f the commencement of adverse weather. It is issued at least once a day.

(2) Cyclone Alert- Issued at least 48 hours before the commencement of the bad weather when the cyclone is located beyond 500 Km from the coast. It is issued every three hours. (3) Cyclone Warning - Issued at least 24 hours before the commencement of the bad weather when the cyclone is located within 500 Km from the coast. Information about time /place of landfall are indicated in the bulletin. Confidence in estimation increases as the cyclone comes closer to the coast (4) Post landfall outlook - issued 12 hours before the cyclone landfall, when the cyclone is located within 200 Km from the coast. More accurate & specific information about time /place of landfall and associated bad weather indicated in the bulletin. 7.29

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Fisherman’s information 1)Dangers to fisherman due to storm are strong winds and associated high seas, due to which fishing boats may capsize. Hence, the fishermen are issued warning when one of the following conditions of weather is expected along and off any coast. 2) Strong off-shore and on-shore winds (or with appropriate direction), speed exceeding 45 kmph; 3)Squally weather – frequent squalls with rain; or persistent type of strong gusty winds (>20kts; 36kmph) accompanied by rain. 4)Gales 5)State of sea very rough or above (wave heights are four meters or more.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Types of Signals for different ports are : General system: General Ports (eleven signals); Extended System: Extended Ports (Six section signals + eleven signals); Brief System: Brief ports (III, IV, VII, X, XI signals) and Minors Ports: Special messages. No signals are hoisted.

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Tropical cyclone strategies are Forecast Strategy: including collection of observations, with enhanced collection in the cyclone vicinity; specialised analysis methods; and the preparation of forecasts using the most appropriate techniques for the situation. Warning Strategy: an explicit understanding of the forecast uncertainties; an appreciation of the most vulnerable and susceptible communities in the potential warning area, the "least regret" approach to ensuring no catastrophes occur; and a sharp sense of timeliness to fit with communication capacities and community cycles. Response Strategy: including public education and awareness programs aimed at ensuring good community responses; developing an infrastructure capable of handling the threat; ensuring a balanced preparation appropriate to the community under threat, to ensure full response without unnecessary over-reaction; taking contingency action, such as establishing emergency operations Centres and implementation of ordered evacuations; and deploying available resources to meet the threat and to be available for post-event response 7.32

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Commonly experienced response factors : Human (personal) factors: Age, sex, health, mobility, education and literacy,

• ccupation, comprehension of danger, family and neighborhood influence, cultural or

religious attitudes, previous experience, poverty and economic circumstance, security

• f house and livestock, urban or rural residence, etc;

Hazard factors: Nature, severity and imminence of hazard(s), hazard frequency, immediate past experience of hazard including warning performance, credibility of warning service, visible evidence of threat, clarity of warnings, vulnerability of the community, etc; Community aspects: Supporting infrastructure, availability of safe shelter and supporting welfare, extent of published evacuation planning, flood-free road access, confidence in counter-disaster officials, evidence of contingency planning, media collaboration to upgrade information, integrity of community lifeline services, level of community awareness, etc 7.33

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• Prof. R. Nagarajan, CSRE , IIT Bombay

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Physical vulnerability maps

• A database of Tropical Cyclone generated Storm Surges impacting the coast from the India Meteorological

Department(IMD)

• The master table for storm surges in AP has 95 entries.
• Because of climate change, projections into future have been limited to 50-year return period.
• All the available cyclone tracks for AP have been synthesized into composite tracks to cover each of the

coastal districts of AP.

• Making use of the projected pressure drop, the IIT-D Storm Surge Model was run using the synthetic tracks

to determine the maximum possible storm surgeamplitude (during a 50-year period) at various locations along the AP coast.

• The Total Water Level envelope was then determined by addition of the tide and wave setup.
• These water levels are then projected onto the coastal land making use of Topography data provided to us

by Government of Andhra Pradesh (GOAP), to demarcate the horizontal extent of inundation.

• This conservative approach may slightly over-estimate the extension of inundation, but is desirable for

hazard mitigation as well as for Coastal Zone Management, and is widely used around the world.

• A more detailed study of inundation as well as calculation of the depth of inundation at various locations on

land could be made ideally with an Irregular Triangular Grid in a Finite Element Model. However, this is not part of our Terms of reference (TOR) and our understanding is that these results may be available from other studies.

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Bulletins issued by IMD?

• Weather and Sea area bulletins.
• Bulletins for Indian Navy.
• Bulletins for Departmental Exchange.
• Port Warnings
• Fisheries warnings
• Four Stage Warnings
• Bulletins for AIR
• Bulletins for Press
• Coastal bulletins
• Warnings to Designated/ Registered Officials
• Aviation Warnings

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Entire Indian coast can be categorized into 4 zones Very high risk zones (Surge height > 5m) High risk Zone (Surge height between 3-5m) Moderate risk zone (Surge height between 1.5 to 3m) Minimal risk zone ( Surge height < 1.5m) The coastal areas and off-shore islands of Bengal and adjoining Bangladesh are the most storm-surge prone (~ 10-13m) – VHRZ East coast of India between Paradip and Balasore in Orissa (~ 5-7m) – VHRZ Andhra coast between Bapatla and Kakinada holding estuaries of two major rivers Krishna and Godavari (~ 5-7m) – VHRZ Tamilnadu coast between Pamban and Nagapattinam (~ 3-5m) – HRZ Gujarat along the west coast of India (~ 2-3m) -MRZ 7.37

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Parameter Weight point

• 1. Inside frequent inundation 33

OR

• 2. Inside 50-year inundation zone 28
• 3. Inside frequent wind zone 19

OR

• 4. Inside 50-year wind zone 14
• 5. Population 5
• 6. Senior citizens

5

• 7. Women 5
• 8. Children under 6 years 5
• 9. Children under 6–15 years 4
• 10. Type of housing 5
• 11. Income level 5
• 12. Cyclone shelters 3
• 13. Hospitals and medical centres 3
• 14. Schools 3
• 15. Scheduled castes, stand backward caste population

5 Total 100

Weightages for cyclone vulnerable areas

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Social Vulnerability (SV) map prepared separately for each Coastal District is

• ne in which the affected Mandals in the District are ranked using a weight-

point system

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Source courtesy: nzdl.org

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Source courtesy: forum.weatherzone.com.au

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Thank you

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Flood – Spillage of liquid or water from the conveyance system onto the sides. It could be either due to excess flow or reduction in capacity of the system

• Temporary water accumulation either due to material infiltration characteristics or elevation

difference (development) Floods in natural river course due to

• Excess run-off from the catchment area –monitoring precipitation / surface cover
• Geodynamic – deposition & erosion
• Embankment – differential elevation / breach of embankment
• Man made structures – flow deflectors

Rivers in Urban areas – river course & capacity alteration, solid & liquid waste dumpings, encroachment

• n river bed, breach of banks, ferrying capacity of bridge etc.

Tidal rivers – tidal conditions, tidal effect buffers (rivulets / water logging section / cross flow section) status of landforms on the river confluence, wetland status etc. Most of the settlements of the past and present are located proximity to the river course (cultivation/river navigation etc) or coast (business) Remnants of ancient civilization are ruined because of river flooding, sea erosion or upwelling. 8.02

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Flood types

Urban flooding is due to lack of drainage in an urban area Ponding happens in relatively flat areas. Rain water falling in an area is normally stored in the ground, in canals or lakes, or is drained away, or pumped out. Flash floods are local floods of great volume and short duration from a torrential rain or cloudburst on relatively a small and widely-dispersed stream. Discharges quickly reach a maximum and diminish almost as rapidly. It also results from the failure of a dam. They are common in mountainous areas and desert regions.. Riverine floods are caused by extensive precipitation over watershed areas or melting of the winter of snow accumulation or by both. They are of short duration in small streams and in large river systems which may continue for periods ranging from a few hours to many days. Catastrophic flooding from rainfall is often aggravated by wind-induced surge along the

• coastline. Storm based High rainfall intensity is capable of producing extreme flood discharges in

both small and large river basins. 8.03

Causes of flooding

Physical Human Intense precipitation Change of land use Prolonged rainfall Urbanisation Snow melt climate change Storm surge Poor dam construction Landslide Volcanic eruption 8.04

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• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

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Hydrological load - The hydrological load was derived from the flood frequency curve of the gauge

Cologne/Rhine based on the annual maximum series from 1961 to 1995 .

Flood routing – routing module consisting of the Muskingum routing method for flood waves in river

channels (Maidment, 1992). The required parameters, travel time K and shape parameter m, were estimated for the defined river reaches from the 35 flood events of the 1961–1995, which were simulated using a 1-dimensional, non-stationary years hydrodynamic model SOBEK

Levee failure and outflow through levee breach - defined two levee breach locations and derived

probabilities of breaches for these two points. Hence the failure probabilities are estimates of levee failure at a certain point, representing the measurement error of the levee geometry. The spatial variability of the levee geometry and the length effect of different long river stretches on the failure probability.

Damage estimation - estimates direct monetary losses within the region. Flood damage can only occur

if the levee system at a place fails. Since the size and location of the inundated areas are not estimated directly by the simple model but as a damage function that relates the damage in the inundated areas to the inflow of water volume after/during a levee failure.

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Impacts Primary effects - Physical damage can damage any type of structure including bridges, cars, buildings, sewerage systems, roadways, and canals. Secondary effects: Contamination of water causing scarce drinking water. Spread of water-borne diseases through unhygienic conditions. Shortage of food Crops and food supplies is caused due to loss of entire harvest. Lowlands near rivers depend upon river silt deposited by floods as nutrients to the local soil. Non-tolerant tree species can die from suffocation. Transport links are disrupted and hard to get emergency aid to those who need it. Tertiary/long-term effects are Economic hardship due to temporary decline in tourism, rebuilding costs, food shortage leading to price increase, etc

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GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.08

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.09

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Source courtesy: archive.deccanchronicle.com Source courtesy: actionwanted.wordpress.com Source Courtesy: articles.economictimes.indiatimes.com

8.10

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.11

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Flood risk is defined as the expected flood water levels. Damage for a given time period need to be investigated and expressed by specifying 1)how large is the current risk in terms of damage per year; 2)determine the potentials of risk reduction and their respective costs and how much is possible to reduce risk and how costly is it; 3)compare the benefits and costs of risk reduction in terms of the benefit- cost ratio and / or the net benefits larger than the costs 4)compare the benefit-cost ratios of several policy fields dealing with risk reduction and decide where the tax money should be spent first. Holistic approach of flood risk analysis consider the flood types and flood events and the hydraulic modeling information about behavior of flood water inundation in flood plains and economic flood damage provide damage- probability curves for individual floodplains in making information for decision making on flood risk management policy.

8.12

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Modules Variability(aleatory uncertainty) Incomplete knowledge(epistemic uncertainty)

Routing annual maximum discharge

• measurement errors

– Plotting Positions formulae – selection of data and partial series – selection of distribution function of annual maximum discharge – sampling uncertainty of annual maximum discharge – parameter estimation for distribution functions Routing changes in river channel over time

• parameter estimations

– error in model selection Stage-discharge- relation –hysteresis during a flood wave

• changes in river channel over time

measurement error – parameter estimation – error in model selection Levee failure

• spatial variation of levee geometry

– substrate distribution measurement errors of levee geometry variability estimations of levee parameters (geometry, substrate, each width, turf) – dimension of levee breaches – turf quality of levee cover Tributaries correlation main river – tributaries extent of correlation, measurement error Damage estimation building use and value– spatiotemporal course of inundation – method of assessing values of buildings and contents-

• error in damage model selection in the polder
• parameter estimation (e.g. stage-damage curves)

8.13

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Modules - Variability Incomplete knowledge (aleatory uncertainty) (epistemic uncertainty) Extreme Value Statistics – annual maximum discharge – measurement errors – Plotting Positions formulae – selection of data and partial series – selection of distribution function of annual maximum discharge – sampling uncertainty of annual maximum discharge – parameter estimation for distribution functions Routing – changes in river channel over time – parameter estimations – error in model selection Stage-discharge-relation – hysteresis during a flood wave – measurement error – changes in river channel over time – parameter estimation – error in model selection Levee failure – spatial variation of levee geometry – measurement errors of levee geometry – substrate distribution – variability estimations of levee parameters (geometry, substrate, breach width, turf) Dimension of levee breaches - turf quality of levee cover Tributaries – correlation main river – tributaries – extent of correlation, measurement error Damage estimation – building use and value – method of assessing values of buildings and contents Spatiotemporal course of inundation – error in damage model selection in the polder – parameter estimation (e.g. stage-damage curves)

8.14

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Flood Hazard Mapping (FHM) is a vital component for appropriate land use planning in preventing the damage of life and property from flooding in the short and long term. It provides information on the past flood records, flood anticipation and potential evacuation routes. It was carried out by gathering, collecting, and analyzing hydrological data, which involved a large number of field observations and calculations. Flood hazard zone designation and relevance are - Zone A is the flood insurance rate zone that corresponds to the 100-year floodplains that are determined in the Flood Insurance Study (FIS) by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no BFEs or depths are shown within this zone. Mandatory flood insurance purchase requirements apply. Zone AE and A1-A30 are the flood insurance rate zones that correspond to the 100-year floodplains that are determined in the FIS by detailed methods. In most instances, BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Mandatory flood insurance purchase requirements apply.. Zone AH is the flood insurance rate zone that corresponds to the areas of 100-year shallow flooding with a constant water-surface elevation (usually areas of ponding) where average depths are between 1 and 3 feet.

8.15

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Flood Hazard Mapping Flood Hazard Mapping (FHM) is a vital component for appropriate land use planning in preventing the damage of life and property from flooding in the short and long term. It provides information on the past flood records, flood anticipation and potential evacuation routes. It was carried out by gathering, collecting, and analyzing hydrological data, which involved a large number of field observations and calculations.

8.16

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Zone AO is the flood insurance rate zone that corresponds to the areas of 100-year shallow flooding (usually sheet flow on sloping terrain) where average depths are between 1 and 3 feet. The depth should be averaged along the cross section and then along the direction of flow to determine the extent of the zone. Zone AR is the flood insurance rate zone used to depict areas protected from flood hazards by flood control structures, such as a levee, that are being restored. requirement regardless of the depth of the BFE at the project site. Zone A99 corresponds to areas of the 100-year floodplains that will be protected by a Federal flood protection system where construction has reached specified statutory milestones. No BFEs or depths are shown within this

• zone. Mandatory flood insurance purchase requirements apply.

Zone D designation is used for areas where there are possible by undetermined flood hazards and no analysis has been conducted.. Zone V is the flood insurance rate zone that corresponds to the 100-year coastal floodplains that have additional hazards associated with storm waves. Zones B,C and X are the flood insurance rate zones that correspond to areas outside the 100-year floodplains, areas of 100-year sheet flow flooding where average depths are less than 1 foot, areas of 100-year stream flooding where the contributing drainage area is less than 1 square mile, or areas protected from the 100-year flood by levees.

8.17

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.18

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Non-urban areas – flooding does not take place at select sections of the course

• Degradation in catchment area.
• River course alteration, dynamics, geo-dynamic process (erosion & sedimentation)
• Change in land cover
• River cross structures
• Functional efficiency of river train structures
• Temporary utility structures in river course
• Landscape & land development on either side of the river

Flood related analysis

• Quantity of flow - Precipitation & run-off based studies
• Conveyance system Identification of vulnerable section – course alteration, train structures,

embankment

• Inundation areas during extreme weather conditions.
• Damage assessment Land utility based estimate
• Relief related Mode & reaching the affected people
• Observation & Information

Static Historical information / record, surveyed maps, estimates etc., Point data Dynamic Observational satellite data – Resource, Meteorological, Tele-communication 8.19

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Flood Warning Systems Flood Warning System (FWS) will increase the community’s time to respond to an emergency. The usefulness will depend on the nature of the catchment area and the flood.

8.20

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

Kosi river course migration

8.21

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.22

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.23

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.24

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.25

Source courtesy: blog.waterdiplomacy.org

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.26

Source courtesy: sb.sarawat.gov.my

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.27

Source courtesy: gmanetwork.com

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.28

Source courtesy: en.gov.nl.ca

GNR 639

• Prof. R. Nagarajan, CSRE , IIT Bombay

GNR 639 : Natural Disaster And Management

8.01

Thank you