Word "Cyclone" is derived from the Greek, word "Cyclos" meaning the coils of a snake.‘Cyclone’ is the term used globally to cover tropical weather systems in which windsequal or exceed ‘gale force’ (minimum of 34 knot, i.e., 62 kmph).These are intense low pressure areas of the earth atmosphere coupled system andare extreme weather events of the tropics. anti-clockwise direction in the Northern Hemisphere and in clockwise direction in theSouthern Hemisphere.known as Hurricane in the Atlantic and Eastern Pacific, Typhoon in Western Pacific,Willy-Willies in Australian,Baguis in the Philippines.
The principal dangers of a cyclone : Gales and strong winds Torrential rain Storm surges or high tidal waves NAMING OF CYCLONECyclones derive their names through a systematic procedure laid down by the WorldMeteorological Organization (WMO) United Nations Economic and Social Commission for Asia and the Pacific (ESCAP).India Meteorological Department (IMD).National disaster management authority (NMDA)Eight north Indian Ocean countries - Bangladesh, India, the Maldives, Myanmar,Oman, Pakistan, Sri Lanka and Thailand - have prepared a list of 64 names.
An air mass is a large body of air that has similar temperature and moisture properties throughout. The best source regions for air masses are large flat areas where air can be stagnant long enough to take on the characteristics of the surface belowOnce the cyclone is fully developed, well-defined frontsappear.A front is defined as the transition zone between two airmasses of different density. Fronts extend not only in thehorizontal direction, but in the vertical as well
INDIAN SCINARIOIndia has a coastline of about 7,516 km,5,400 km along the mainland, 132 km inLakshadweep and 1,900 km in the Andamanand Nicobar Islands.Thirteen coastal states and UnionTerritories (UTs) in the country are affectedby tropical cyclones. Four states (Tamil Nadu,Andhra Pradesh, Orissa and West Bengal)and one UT (Pondicherry) on the east coastand one state (Gujarat) on the west coastare more vulnerable to cyclone hazards.
Major Tropical Cyclone Disasters during the past 270 Years in terms of Human Loss
Various Types of Cyclonic Disturbances formed in the Bay of Bengal Affecting theEast Coast of India between 1891 and 2000
CYCLONES PARAMETERS CONSIDERATIONTo determine the degree of proneness the following parameters have been considered. 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)
By : NDMA(national disaster management authority)
Main Objectives of NCRMPThe National Cyclone Risk Management Project (NCRMP)
DESIGN GUIDELINES FOR BUILDINGSi) The design to be carried out for 1.3 times the basic wind speed as recommended in the IS 875 - 1987 part 3.The basic wind speed as per the code in most parts of the coastal zone is 50 m/s (180 km/hour) up to10 m above ground level. Further, a number of corrections are to be applied based on the importance of thestructure (risk assessment), topography, size and shape of the building.ii) The design will also be able to withstand seismic forces in regions which are additionally vulnerable toearthquake hazard, such as Kandla, etc.iii) The local community will be encouraged to construct houses which will be cyclone resistantiv) Sloping RCC roofs (say 1 in 5 or 6 slope) will be used to provide quick rain water drainage and avoid anyseepage or leakage.v) Minimum M30 Concrete grade (concrete having a characteristic strength of 30 N/mm2) and reinforcement steelof Fe415 grade will be used in the construction. A design concrete mix as specified by IS Code 456will be adopted.vi) An extra cover of 5 mm beyond that specified in IS: 456 for the relevant exposure condition is to be providedfor steel reinforcement.vii) The walls and all the RCC work will be plastered with cement mortar of 1:4. The outside plaster can be in twocoats. The building will have suitable cement plaster coating both outside and inside.
viii) The doors and windows will be of aluminium with anodized fixtures. The size and thickness of the doors andwindows must be of heavy gauge quality.ix) All inserts and fittings will be of structural aluminiumx)The plinth height of 1.5 m will be used for stilt with the height varying from 2.5 m to 4.5 m if the storm surgelevel is more than 1.5 m and less than 4.5 m. In all cases, the floor level will be at least 0.5 m above the possiblemaximum surge level.xi)The foundation will be taken to a depth equal to that of the surge level to avoid scouring, subject to a minimumof 1.5 m.xiii) The shelter will have a rectangular or polygonal plan depending on the functional aspect, with curved cornersfor better aerodynamic features and the non-erosion of walls. A rectangular plan with curved corners is morefunctional for many aspects.
implementationsThe cyclone DM approach aims to institutionalise the implementation of initiatives and activities covering allcomponents of the DM cycle including prevention, preparedness, mitigation, relief, rehabilitation and recovery,with a view to developing communities that are well informed, resilient and prepared to face cyclone-relatedemergencies with minimal loss of life and property. Therefore, it will be the endeavour of the centraland state governments and local authorities, including ULBs and PRIs, to ensure implementation of theseguidelines. BIS :Bureau of Indian Standards MoUD & PA : Ministry of Urban Development and Poverty Alleviation SDMA : State Disaster Management Authorities