Cyclone - Impacts of cyclone on Agriculture

1. Tropical cyclones – Genesis -
Its effect on agriculture over Tamilnadu
Student
AP. Ramaraj
11 – 605 - 003
AMT 691 CREDIT SEMINAR (0+1)
Chairman
Dr.V.Geethalakshmi
Professor, ACRC
Members
Dr. A. Lakshmanan
Dr. S. Enayathullah Shah
Dr. K. Soorianathasundaram

2. PROLOGUE
• What is a Cyclone ?
• Where it forms ?
• How it forms ?
• When it forms ?
• What happens on landfall ?
• What is storm surge ?
• Case study
• Conclusion

3. Cyclone
 Greek word ‘cyclos’ - ‘coiling of a
snake’ - Heary Piddington
 A rotational low pressure system in
tropics when the central pressure falls
by 5 to 6 hPa from the surrounding and
maximum sustained wind speed reaches
about 62 kmph.
 Violent whirl - 150 to 800 km spiraling
around a centre
 Progressing along the sea - 300 to 500
km a day
- IMD

4. Definitions
Tropical Cyclone (TC) Generic term for a non-frontal synoptic-scale
low pressure system over tropical or subtropical
waters with organized convection and a definite
cyclonic surface wind circulation
Tropical Depression (TD) TC - maximum sustained surface winds < 17 m/s
Tropical Storm (TS) TC with maximum sustained surface winds > 17
m/s
Becomes a “named” system
Hurricane (H) TC with maximum sustained surface winds > 33
m/s
- CDC, NOAA

5. Sustained Wind
Wind speed determined by averaging observed values over a given
amount of time (either 1-min or 10-min)
1-min: U.S. National Hurricane Center (Atlantic / East Pacific)
Joint Typhoon Warning Center (Pacific / Indian)
10-min:
India Indian Meteorological Department (North Indian)
Japan Japanese Meteorological Agency (West Pacific)
France MeteoFrance (South Indian)
Australia Regional TC Centers (Australian Region)
Fiji Regional TC Centers (South Central Pacific)
22
26
30
34
38
1 61 121 181 241 301 361 421 481 541
Time (s)
WindSpeed(m/s)
1-min Mean = 30.6 m/s 10-min Mean = 26.3 m/s
- CDC, NOAA

6. CYCLONE TYPES
 Tropical cyclone (TC)
- between the 23.5°N to 23.5°S
 Extra – tropical cyclone / Mid latitude
- between 23° - 66°N and
23° - 66°S
 Extra-tropical cyclones are low
pressure systems with associated cold
fronts, warm fronts, and occluded
fronts.
 Energy - horizontal temperature
contrasts that exist in the atmosphere
- CDC, NOAA

7. Tropical Cyclone - Locations
- Gray, 1968

8. CYCLOGENESIS (Tropical Cyclone)
Tropics - weak pressure waves - east to west - easterly waves
Favourable situation - a low pressure area forms
Low level convergence
SST > = 26.50
C - upper level divergence
Air is blown off at higher levels from the area of low pressure
Vertical motion - moist air upwards - condense – LHC
Due to LHC – warms – pressure falls
Low pressure System
Depression
Deep depression
Cyclonic storm
- IMD

9. Common Factors Favorable for Development
 Warm Sea Surface Temperatures (SSTs)
• Generally > 26.5°C
• TCs are most common over waters > 28ºC
 Low vertical wind shear near the center of the system
• 200 - 850 mb difference; usually < 20 m/s
• TCs are most common in regions with shear < 10 m/s
 Significant planetary vorticity
• Coriolis force; usually poleward of 5°
• Most TCs occur in the 10º-20º latitudinal belts
 Moist troposphere
• Generally > 40-50% at mid-levels
- Gray, 1968

10. Contd.,
 An atmosphere which cools fast enough with height
 Relatively moist layers near the mid-troposphere (5 km)
 A minimum distance of at least 500 km from the equator. For
tropical cyclogenesis to occur, there is a requirement for non-
negligible amounts of the Coriolis Force - gradient wind balance
to occur
 Without the Coriolis Force, the low pressure of the disturbance
cannot be maintained
- Gray, 1968

11. Classification of the system
 The pressure criteria are used, when the system is over land and
wind criteria is used, when the system is over the sea
- IMD

12. Structure of a TC
Size
 Indian seas varies from 100 km
radius to 2000 km with an average of
300 –600 km
Eye
 The "eye" is a roughly circular area
found at the centre of a cyclone
 The eye is the region of lowest surface pressure and warmest temperatures
 Eyes - 8 km to over 200 km, approximately 30-60 km in diameter
 Eye temperature - 10°C warmer (12 km) 0 - 2°C warmer - surface - IMD

13. Eyewall
Circular ring of deep convection, which is the area of highest surface winds
Rain bands
Eyewall convection - organized into long, narrow rainbands which are
oriented in the same direction as the horizontal wind called ” Rain bands ” -
upper-level divergence is most pronounced
- IMD

15. ANONYMS OF CYCLONE
 Indian Seas – Cyclone
 Atlantic – Hurricanes
 Pacific – Typhoons
 Australia – Willy-willies
- G.S.L.H.V. Prasada Rao,

16. RSMC - TC
RSMC,
New Delhi

The WMO/ ESCAP Panel on
Tropical Cyclones
The RSMC tropical cyclones
New Delhi gives a tropical
cyclone an identification name
from a prepared list.
- IMD

17. Current List of Names
Members Names
Bangladesh Onil Ogni Nisha Giri
India Agni Akash Bijli Jal
Maldives Hibaru Gonu Aila Keila
Myanmar Pyarr Yemyin Phyan Thane
Oman Baaz Sidr Ward Murjan
Pakistan Fanoos Nargis Laila Nilam
Sri Lanka Mala Rashmi Bandu Mahasen
Thailand Mukda Khai Muk Phet Phailin
- IMD

18. Ocean Basins
• The tropical cyclones form over ocean basins in lower latitudes of
all oceans except south Atlantic and southeast Pacific.
• The tropical cyclones develop over the warm water of the Bay of
Bengal and the Arabian Sea
Statistics on frequency of cyclone (1891 -2011)
Statistics Cyclonic
disturbances Cyclones Severe cyclones
BOB AS BOB AS BOB AS
Sum 1170 207 498 118 221 69
Average 10 2 4 1 2 1
Max 16 6 9 5 6 4
Min 3 0 0 0 0 0
BOB – Bay of bengal AS – Arabian sea
- IMD

19. CYCLONE FREQUENCY
- IMD

20. MONTHLY FREQUENCY OF CYCLONIC EVENTS
Study period – 1891 – 2011
Max – October
Min - February - IMD

21. Number of Cyclones made landfall (1971 – 2010)
- NDMA

22. TC – Monsoon
• Tropical cyclone activity over the North Indian Ocean has a distinct
bimodal character with relative maxima in OCT – NOV and MAY
• During the periphery of the monsoon season, monsoon depressions
tend to have longer tracks over water such that they may evolve into
tropical cyclones.
• It has been shown by many studies that the MJO exerts a large
influence on the Indian monsoon system. Primarily, this influence is
related to enhanced and break monsoon periods
- Ajayamohan, 2001

23. TC – ENSO
• The El-Nino – Southern Oscillation
(ENSO) influence on tropical cyclone
(TC)
• (Frequency, genisis location and
intensity) - is negatively correlated.
• Under Anti – El Nino ( La-Nina ) regime
number of extreme TC cases increase
significantly
• The existence of low-level cyclonic
vorticity, enhanced convection, and high
tropical cyclonic heat potential (TCHP)
in BOB provides faourable condition for
TC under Anti – El Nino regime
together with weak wind shear and high
SST
- Krishnamoorthi et al ., 1985

24. CYCLONE AND AGRICULTURE

25. - NDMA
Cyclone damage Risk Zones

26. Coastal Zone of TamilNadu
Tamil Nadu – Districts along the coast
 Chennai,
 Cuddalore,
 Kanchipuram,
 Kanniyakumari,
 Nagappattinam,
 Pudukkottai,
 Ramanathapuram,
 Tiruvallur,
 Thanjavur,
 Tiruvalur,
 Tuticorin,
 Viluppuram,
 Tirunelveli
- NDMA

27. DEVASTING EFFECT OF CYCLONE

28. Cyclone Accounts
• Worst cyclone on record is that of October 1737: hit Calcutta and took a
toll of 3,00,000 lives. It was accompanied by a 12 metre high surge
• Rameswaram Cyclone of 17th to 24th December 1964 wiped out
Dhanuskodi in Rameswaran Island from the map.
• A passenger train which left Rameswaram Road station near about the
midnight of 22nd was washed off by the storm surges sometimes later,
nearly all passengers traveling in the train meeting water graves.
• Bangla Desh Cyclone of 8-13 November 1970 which crossed Bangla
Desh coast in the night of 12th was one of the worst, with storm surges
of 4 to 5 metres height at the time of high tides, and with 25 cm of rain
in the areas, the inundation took toll of about 3,00,000 people.

29. CYCLONE Vs AGRICULTURE
• RAINFALL
• WIND
• STORM SURGE

30. Rainfall
• Intensive Rainfall - left of the Cyclone
• Maximum rainfall occurs close to the centre
• Secondary maximum - right of the storm
centre
• Slow moving/big size cyclones give more
rainfall, whereas, fast moving/small size ones
give less rainfall
• More than 90% of rainfall is limited within
200 Km radius of the storm
- CDC, NOAA

31. Contd .,
• Governing factors for rainfall distribution and intensity are intensity,
speed and size of the storm and local effects such as topography and
orientation of the coast
• The rainfall can vary from trace/ nil rainfall - to maximum rainfall
upto 50-60 cm per day
• Super cyclone which crossed Orissa coast near Paradip on
29th
October 1999 recorded 24 hr cumulative rainfall of about 52 cm

32. • The degree of a tropical cyclone rainfall impact depends upon speed
of movement, storm size, and degree of vertical wind shear
• One of the most significant threats from tropical cyclones is heavy
rainfall.
• The presence of mountains/hills near the coast, acts to magnify
rainfall potential
Contd .,
- CDC, NOAA

33. Rainfall based on Radius
Rainfall Rate per day within radius of the center
Topographic effect and Wind shear not considered
- Riehl,1954
Radius (Km) Amount ( mm)
56 863
12 337
224 108
448 30

34. STORM SURGE
Astronomic Tide:
Storm Tide: Astronomic Tide + Storm surge
- JTWC

35. STORM SURGE
The height of the surge depends on:
– The intensity of the cyclone - as the winds increase, the sea water is
piled higher and the waves on top of the surge are tall
– The forward speed of the cyclone - the faster the cyclone crosses the
coast, the more quickly the surge builds up and the more powerfully it
strikes
– The angle at which the cyclone crosses the coast - local zones of
enhanced surge in areas such as narrow inlets and bays
– The shape of the sea floor - the surge builds up more strongly
if the slope of the sea bed at the coast is shallow
• Past history indicates that loss of life is significant when surge magnitude
is 3 metres or more and catastrophic when 5 metres and above
- JTWC

36. Impacts of Flood
• Rainfall is generally very heavy and spread over a large area thus leading
to excessive amount of water, which leads to flooding
• Standing crop – Total Loss
• Coastal areas with saline water, resulting in salinity of agricultural land.
• Coastal and estuarine plains in cyclone paths are generally vulnerable
• Deposition by floods of a layer of alluvium on cultivated land may bury
crops and change soil quality
• Potential may be lowered if the deposits are rather infertile and drought-
prone sandy matter.
- FAO, 1999

37. Contd.,
• Soil erosion also occurs on a large scale
• Heavy rains log the ground and cause softening of the ground due to
soaking
• This contributes to weakening of the embankments
• Massive erosion has occurred, taking away essential topsoil that is
necessary for plant nutrients
• It is hard to replace so much fertile soil in a short period of time so that the
affected countries can begin the recovery process
• Flood stressed trees are prime targets for attack by secondary organisms
including certain root and collar-rot diseases, in conjunction with mould
fungi, Phytophthora spp. and Pythium spp.
- FAO, 1999

38. Category : Cyclonic storm, T Number : T 2.5 Damage Category : Minor to Moderate
Agriculture : Some damage to paddy crops, Banana, Papaya trees and orchards.
Category : Severe Cyclonic storm , T Number : T3.5 Category : Moderate
Agriculture : Breaking of tree branches, uprooting of large avenue trees. Moderate damage
to Banana and Papaya trees. Large dead limbs blown from trees.
Category : Very Severe Cyclonic storm , T Number : T4.0 – 4.5 Category : Large
Agriculture : Widespread damage to standing crops plantations, orchards, falling of green
coconuts and tearing of palm fronds Blowing down bushy trees like mango.
Category : Very Severe Cyclonic storm , T Number : T5.0 – 6.0 Category :Extensive
Agriculture :Extensive damage to standing crops plantations, orchards. Blowing down of
Palm and Coconut trees. Uprooting of large bushy trees.
Category : Super Cyclonic storm , T Number : T 6.5 and above Category :
Catastrophic
Agriculture :Total destruction of standing crops/orchards, uprooting of large trees &
blowing away of palm and coconut crowns, stripping of tree barks.
Impact of Wind
- FAO, 1999

39. Cyclone ‘NILAM’ (2012)
Impacts Details
Bay of Bengal - Low pressure October 28
Cyclonic Storm October 30
Landfall - Mahabalipuram October 31(peak winds of 85 km/h)
Andhra Pradesh
Agriculture and Horticulture crops Rs 1,710 crore.
Paddy and Cotton 7.72 lakh hectares
Horticulture crops (AP) 52,000 hectares
TamilNadu 800 mm Rainfall (past fortnight)
Submerged crop land over 81,100 hectares
Full submergence 51,486 ha - Directly sown
13,421 ha - Transplanted
Part submergence 4,404 ha - Directly sown
12,189 ha - Transplanted
The Hindu

40. CYCLONIC EVENTS - 2012
Five depressions have formed
Four intensified into deep depressions
Two of them became cyclonic storms
Both the storms made landfalls
MURJAN
NILAM - IMD, 2012

41. Case study - ‘ THANE ’
Tsunami was nothing compared to this
cyclone.
- A Fisherman

42. Path of THANE
Crops damage - THANE
THANE
THANE

43. Crop Losses
Central team Assesment
 Total losses of Rs 5,250 crore projected by the government on account of
the cyclone
 Cuddalore's share alone would exceed Rs.4,000 crore
 With agricultural and horticultural crops on two lakh hectares damaged
 Cuddalore district alone accounted for over one lakh hectares of such
crops
- Hindu

44. CROPS Cultivated (acres) Fully Damaged Partially Damaged
Paddy 55,630 45,632 3,060
CASH CROPS
Cashew 50,810 40,421 60
Banana 7,935 5,344 11
Groundnut 13,895 7,823 2,193
Sugarcane 19.432 16,002 623
Tapioca 590 440 25
Pulses 1,586 1,386 NA
Flowers 549 473 20
TOTAL 94,788 71,889 2,932
TREE CROPS
Jack Fruit 10,982 10,748 10
Coconut 16,377 16,377 91
Mango 665 665 5
Casuarina 8,568 8,568 88
Other Trees 250 250 NA
TOTAL 36,842 36,842 194

45. Trees Uprooted
Trees Numbers
Banyan tree 176
Teak 97923
Tamarind 20214
Neem 39825
Palmyra 760
Eucalyptus 125
Bamboo 5000
Country teak 1525
Other 625
- KVK, Vridachalam

46. CONCLUSION
• Bay of Bengal – Protection and Management
• Impact on Monsoon
• Influence of ENSO, MJO, QBS have to be studied at a regional Scale
• Agriculture, Construction – To be planned to suit the degree of proness
• Identification of crop, livestock, fisheries and forestry practices and
farming systems suitable for vulnerable areas

47. THANK YOU
ON THE WAY - MAHASEN