Transcript Slide 1

Cyclone Hazard Risk Profile of Coastal
Districts of India
M. MOHAPATRA,
G.S. MANDAL*, B. K. BANDYOPADHYAY and AJIT TYAGI
India Meteorological Department
Mausam Bhavan, Lodi Road, New Delhi-1100 03.
Presentation Layout
• Introduction
• Data and Methodology
• Results and discussion
• Conclusions
Tropical Cyclone
Eye-wall
Eye
Spiral cloud bands
 Extreme Weather Events
 Causes major loss of lives and live
stocks.
 In single event 2 to 3 lakh people lost
lives.
(Bangladesh
Cyclone,
November 1970.)
 Only weather system which bears
name or identification because of long
life.
Convective cells
Low pressure system
Low (<17 knot)
Depression (17-27)
Deep Depression (28-33)
Cyclone (34-47)
Severe Cyclone (48-63)
Very Severe Cyclone (64-119)
Super Cyclone (12 and above)
Potential damages due to tropical cyclones
FLOODING OF COASTAL AREAS
CYCLONE
LOCAL TIDES
STORM
SURGE
LOCAL COASTAL
CONFIGURATION
EROSION OF BEACHES
LOSS OF SOIL FERTILITY FROM
SALINE INTRUSIONS
DAMAGE TO STRUCTURES
LOSS OF
POWER/COMMUNICATION
WIND
INJURIES & LOSS OF LIFE
DESTRUCTION OF CROPS,
VEGETATION, LIVE-STOCK
CONTAMINATION OF WATER
SUPPLY SYSTEM
RAIN
LAND SUBSIDENCE
FLOODING OF INLAND AREA
North Indian Ocean
 Special features
 globe, five form over north
Indian Ocean
 Ratio of TCs between Bay of
Bengal and Arabian Sea –
4:1
 Year to year variation - Quite
large
 13 coastal States/UTs are
vulnerable to cyclones
• Bay of Bengal is a vast warm pool adjoining the warm pool of the western
North Pacific. Several of the precursors of the Bay of Bengal cyclones
emerge from the neighbouring Pacific basin as remnant of typhoons and
re-intensify over the Bay after passing over rather narrow strip of SE Asian
countries
• Ocean currents in the Bay of Bengal are quite complex and in the postmonsoon season low salinity warm waters begin to cover eastern coastal
waters from October to December through the East India Coastal Current
Objective
 IMD is the nodal Govt. agency to provide cyclone warning
services in India.
 There is no accepted definition to define cyclone prone district.
 For better cyclone disaster management in the country it is
necessary to define cyclone proneness and identify cyclone
prone coastal district.
 Necessary to decide degree of hazard proneness of a district to
prioritize mitigation measures and for sustainable land use
planning.
 Study made an attempt to prepare a list of Cyclone Prone
Districts by adopting Hazard criteria.
Earlier Study
 Frequency and intensity of cyclones crossing different coastal
states and different latitudinal belpts
 Vulnerability Atlas of India (BMTPC-Ministry of Urban Development)
 Based on above study identification of cyclone prone district by a
Committee headed by Prof. A.S.Arya.
 National Cyclone Guidelines prepared by NDMA also listed the
same.
State
Total No.
West Bengal
69
Orissa
98
Andhra Pradesh
79
Tamil Nadu
62
Karnatka
02
Maharashtra & Goa
18
Gujarat
28
Kerala
03
Past Studies
Past Studies
Probable Maximum Storm Surge in meters
for each coastal District
A shallower bathymetry
piles up the surge more
Source: IMD
 For the purpose of
study, the following
districts has been taken
into consideration :
Districts
coast.
touching
Coastal districts as
per the Vulnerability
Atlas
of
India
published by BMTPC.
Districts considered
as coastal districts
for the issue of
cyclone warning by
India Meteorological
Department (IMD).
Data and Methodology
Data and Methodology
 To find out cyclone proneness of a district, a composite rating
procedure has been adopted based on five parameters, viz
 Total number of Tropical Cyclones,
 Total number of severe Tropical cyclones,
 Maximum wind,
 Probable maximum storm surge and
 Probable maximum precipitation for any station in the district.
These parameters take into consideration the frequency and
intensity of TCs along with associated adverse weather
conditions.
Based on different categories of ratings, the districts have been
classified into moderately prone, highly prone and very highly
prone districts.
Data and Methodology
• Data on cyclone, severe cyclone and very severe cyclone
frequencies affecting each district
• India Meteorological Department has brought out an
electronic version “Tracks of Storms and Depressions in the
Bay of Bengal and the Arabian Sea”, which were published by
IMD in the years 1964, 1979 and 1996.
• IMD publication Mausam Journal
• Data for Max Wind, Probable Max Storm Surge and Probable Max
Precipitation
• Vulnerability Atlas published by BMTPC, Ministry of Urban
Affairs, Govt. of India, which again based on data of IMD.
• IMD publication in Mausam Journal
• PMP Atlas published by IMD
• Storm Surge Monograph published by IMD
Categorisation of districts based on
degree of proneness
 Different districts have been
rated in a 10 point scale as per
the following four categories
with the above parameter.
 The intensity of proneness has
been discussed accordingly.
Category
Rating
Low (P4)
≤ 3.0
Moderate (P3)
3.1 – 5.0
High (P2)
5.1 – 7.0
Very high (P1)
7.1 – 10.0
• Different ratings used for different cyclone parameters.
• The same scale has been used as that in Vulnerability Atlas for the
rating purpose to maintain conformity.
Rating based on cyclones and severe
cyclones crossing the district
(a)Total number of cyclones
Category
1-5
Rating
3
6-10
11-15
>15
5
7
10
(b) Total no. of severe cyclones
Category
Rating
1-3
3
4-6
5
7-10
7
>10
10
Rating based on PMW and PMSS
(c) Maximum wind (mps) over the district
Category
Rating
≥50
10
44-49
7
39-44
5
<39
3
No. CS
0
(d) Probable maximum storm surge over the district
Surge height
Rating
Upto 2.0
3
2.1-4.0
5
4.1-6.0
7
>6
10
District Rating
(d) Probable daily maximum Precipitation (in cm) over the
district
Category
Rating
PMP (cm)
Rating
1-10
3
1-20
3
11-20
5
21-30
5
21-30
7
31-40
7
>30
10
>40
10
PMP (cm)
Rating
1-40
3
41-50
5
51-60
7
61 and above
10
• The rating scale is same for maximum wind as used in
vulnerability atlas.
District Rating
 A composite score/rating has been calculated taking the arithmetic
mean of all ratings.
 The composite score has been further been divided into four
categories like
 low (≤3),
 moderate (>3 and ≤5),
 high (>5 and ≤7) and
 very high (>7)
to find out the intensity of cyclone proneness of districts.
For islands and some districts for which PMSS is not available, the
composite rating has been found out using remaining parameter.
Methodology (i) Different Weights
•
Classification of Districts as Low, Medium, High and Very
High based on weight:
i.
ii.
iii.
iv.
v.
Total number of cyclones crossing districts (w1)
Total number of severe cyclones crossing districts (w2)
PMP for the district (w3)
Strong wind affecting the district (w4)
PMSS for the district (w5)
=1
=2
=2
=3
=5
(Maximum weight is given to storm surge followed by wind,
as the maximum hazard is associated with storm surge followed
by wind.)
Methodology (ii) Equal Weights
•
Classification of Districts as Low, Medium, High and Very
High based on equal weight to all parameters:
i.
ii.
iii.
iv.
v.
Total number of cyclones crossing districts (w1)
Total number of severe cyclones crossing districts (w2)
PMP for the district (w3)
Strong wind affecting the district (w4)
PMSS for the district (w5)
=1
=1
=1
=1
=1
Methodology(iii)
Cyclone Prone Districts based on BMTPC Wind Atlas
 The above classification has the
limitation
distinguish
as,
it
does
between
not
the
maximum wind due to squall and
that due to cyclone
 As a result it gives almost uniform
weightage to all districts in east
coast.
Methodology (iv)
Cyclone Prone Districts based on actual wind
Actual wind is collected from the reports published by IMD for the period
1971-2008 in MAUSAM
 Weightage to wind is given based on Damage Potential published by
IMD
 According to damage potential, wind has been classified in this study
into four categories. Overall damage as largr, extensive and
catastrophic has been grouped together with highest rating
System
Wind speed
Rating
Cyclonic Storm:
34-47 Knots (62-87 Kmph)
03
Severe Cyclonic Storm
48-63 Knots (88-117 Kmph)
05
Very severe Cyclonic Storm
64-90 knots (118-167 kmph)
07
Very Severe Cyclonic Storm
91-119 knots (168-221 kmph)
10
Super Cyclonic Storm
120 knots and more
10
(222 kmph or more)
Impact of Cyclonic Storms
Category : Cyclonic storm T Number : T2.5
Wind speed : 34-47 Knots 62-87 Kmph
Structures : Damage to thatched huts
Communication and power: Minor damage to power and communication lines
due to breaking of tree branches.
Road/Rail : Major damage to Kutcha and minor damage to Pucca roads.
Agriculture : Some damage to paddy crops, Banana, Papaya trees and
orchards.
Marine Interests : High to very high sea waves about 6-9 m high.
Coastal Zone : Sea water inundation in low lying areas after erosion of
Kutcha embankments
Overall Damage Category : Minor to Moderate
Impact of Cyclones
Category : Severe Cyclonic storm ,
T Number : T3.5
Wind speed : 48-63 Knots (88-117 Kmph)
Structures : Major damage to thatched houses / huts. Roof tops may blow off.
Unattached metal sheets may fly.
Communication and power: Minor damage to power and communication lines.
Road/Rail : Major damage to Kutcha and some damage to Pucca roads.
Flooding of escape routes.
Agriculture : Breaking of tree branches, uprooting of large avenue trees.
Moderate damage to Banana and Papaya trees. Large dead limbs blown
from trees.
Marine Interests : Phenomenal seas with wave height 9-14 m. Movement in
motor boats unsafe.
Coastal Zone : Major damage to coastal crops. Storm surge upto 1.5m (area
specific) causing damage to embankments/ salt pans. Inundation upto 5 Km
in specific areas.
Overall Damage Category : Moderate
Impact of Cyclones
Category : Very Severe Cyclonic storm ,
T Number : T4.0 – 4.5
Wind speed : 64-90 Knots (118-167 Kmph)
Structures : Total destruction of thatched houses/ extensive damage to
Kutcha houses. Some damage to Pucca houses. Potential threat from
flying objects.
Communication and power: Bending/uprooting of power and commn poles.
Road/Rail : Major damage to Kutcha and Pucca roads. Flooding of escape
routes. Minor disruption of railways, overhead power lines and signaling
systems.
Agriculture :Widespread damage to standing crops plantations, orchards,
falling of green coconuts and tearing of palm fronds Blowing down bushy
trees like mango.
Marine Interests : Phenomenal seas with wave heights more than 14m.
Visibility severely affected. Movement in motor boats and small ships
unsafe.
Coastal Zone : Storm surge up to 2 m, Inundation up to 10 Km in specific
areas. Small boats, country crafts may get detached from moorings.
Overall Damage Category : Large
Impact of Cyclones
Category : Very Severe Cyclonic storm , T Number : T5.0 – 6.0
Wind speed : 91-119 Knots (168-221 Kmph)
Structures : Extensive damage to all types Kutcha houses, some damage to
old badly managed Pucca structures. Potential threat from flying objects.
Communication and power: Extensive uprooting of power and communication
poles.
Road/Rail : Disruption of rail / road link at several places.
Agriculture :Extensive
damage to standing crops plantations, orchards.
Blowing down of Palm and Coconut trees. Uprooting of large bushy trees.
Marine Interests : Phenomenal seas with wave heights more than 14m.
Movement in motor boats and small ships not advisable.
Coastal Zone : Storm surge up to 2 – 5 m, Inundation may extend up to 10-15
Km over specific areas. Large boats and ships may get torn from their
moorings, country crafts may get detached from moorings
Overall Damage Category :Extensive
Impact of Cyclones
Category : Super Cyclonic storm ,
T Number : T 6.5 and above
Wind speed : 120 Knots and above (222 Kmph and above)
Structures :Extensive damage to non concrete residential &industrial building.
Structural damage to concrete structures. Air full of large projectiles.
Communication and power: Uprooting of power and communication poles.
Total disruption of communication and power supply.
Road/Rail : Extensive damage to Kutcha roads and some damage to poorly
repaired pucca roads. Large scale submerging of coastal roads due to
flooding and sea water inundation. Total disruption of railway and road
traffic due to major damages to bridges, signals and railway tracks.
Washing away of rail / road links at several places.
Agriculture :Total destruction of standing crops/orchards, uprooting of large
trees & blowing away of palm and coconut crowns, stripping of tree barks.
Marine Interests : Phenomenal seas with wave heights more than 14m. All
shipping activity unsafe.
Coastal Zone : Extensive damage to port installations. Storm surge more than
5m, Inundation up to 40 Km in
specific areas and extensive beach
erosion. All ships torn from their moorings. Flooding of escape routes.
Overall Damage Category :Catastrophic
Classification of cyclone prone districts
State
Orissa
Orissa
Orissa
Orissa
AP
AP
AP
West Bengal
West Bengal
Districts
Balasore
Kendrapara
Bhadrak
Jagatsinghpur
Nellore
East Godavari
Krishna
South 24-pargana
Medinipur
Cyclone Parameters
Total no. Wind
No. of severe
of
speed
PMSS
cyclones
cyclones (knot) (metre)
5
28
75
11
4
16
140
8.5
3
15
65
9.5
4
14
140
6.5
8
18
110
4.5
4
17
125
4.5
3
10
127
5.5
16
29
115
12
8
16
115
13
PMP
(cm)
60
60
60
60
60
52
56
52
56
Classification of cyclone prone districts
Ratings based on
State
AP
Districts
Nellore
AP
East Godavari
AP
Krishna
Orissa Balasore
Orissa Kendrapara
Orissa Jagatsinghpur
Orissa Bhadrak
WB
South 24pargana
WB
Medinipur
No. of
Total Wind PMSS PMP
severe
no. of speed
Catcyclone cyclone
Mean egory
7
10
10
7
7
8.2
P1
5
10
10
7
7
7.8
P1
5
5
5
5
5
10
7
7
10
10
10
10
10
10
10
7
10
10
7
10
10
7
10
10
10
10
10
10
7
7
7
7
7
7
7
7.2
7.8
8.4
8.4
P1
P1
P1
P1
7.8
P1
9.4
P1
8.8
P1
Classification of cyclone prone districts
 All coastal districts
prone.
are cyclone
 Therefore, it become imperative to
decide degree of proneness.
 In general, coastal districts in WB,
Orissa, AP & TN are in high to very
high category.
 Some interior districts
India(earlier included in
atlas) excluded.
in NE
BMTPC
 Cyclone proneness is very high for
the districts of south 24 praganas &
Midnapore (West Bengal), Balasore,
Kendrapara, Bhadrak, Jagatsinghpur
& Ganjam (Orissa), Nellore, Guntur,
east Godabari (Andhra Pradesh)
Classification of cyclone prone districts
 Considering variable weightage of parametres pictures, become to
some extent, unrealistic.
 Results with equal weight and hazard parameters give realistic picture
of hazard proneness.
 Categorization of districts with degree of proneness tallies with
observed pictures.
 Analysis does not include vulnerability aspects. As such, do not
represent total risk.
 Separate studies need to be carried out in micro-scale to determine
composite risk of an area/place.
 Apart from its utility in monitoring, prediction and early warning of TCs
over small spatial scale, the studies can be utilized for district planning,
especially for relief & rescue operation, cyclone shelter construction and
socio economic development.