Guidelines for Design and Construction of Cyclone/Tsunami Shelters

Cyclones are destructive because of their associated long duration high rotatory winds, very heavy rainfall and storm surge. It is more so when they strike coasts of countries/states bordering the North Bay of Bengal. In the past, 21 out of 24 cyclones with large loss of lives (human deaths 10000 or more associated with cyclone disasters) in the globe took place in these areas. This was due to very serious storm surge problem of the region. In the past, some of the record storm tides (combined effect of surge and astronomical tides) of the world, upto 13 m have been observed in this region. Shallow
bay, low flat zigzag terrain, high astronomical tides, high density of population, socio economic conditions, lack of awareness, inadequate preparedness and absence of hedging mechanisms add to the problem. The only prescribed measures to save vulnerable population from the onslaught of storm surges are to temporarily evacuate the population on receipt of warnings and look after them for 2-3 days by arranging shelters, food and health care facilities. Therefore, construction of shelters along vulnerable coastal areas is one of the important cyclone mitigation measures.

Most parts of coastal India are susceptible to high wind speed exceeding 50 m/s (180 km/h) and probable maximum storm surge height varying from 12.8 m near Contai in West Bengal to about 2.5 m near Vishakhapatnam in Andhra Pradesh along the East coast and 5 to 6 m in the Gulf of Cambay region and about 2.1 m near Tiruvanthapuram in Kerala on the west coast. Surge varies from place to place and variation is not linear. At some places, variation of surges between two points close to each other are large due to bathemetry and terrain conditions. These facts have to be taken into consideration
while designing the cyclone shelters.