Disasters are sudden and intense events which result in considerable destruction, injuries & deaths, disrupting normal life as well as the process of development. Increasing population and various other socio-economic factors have forced people to live in vulnerable areas. Disasters are perceived to be on the increase in terms of their magnitude, frequency, and economic impact. Unique geo-climatic conditions make the Indian region particularly vulnerable to disasters. Floods and high winds account for around 60 percent of all disasters. About 54 percent of the sub-continent‟s landmass is vulnerable to earthquakes, while about 4 crore hectares, that is, about 12 percent of the country is vulnerable to periodic floods. New disaster threats have also developed, such as the tsunami disaster of December 2004 which was an unprecedented natural disaster. The total expenditure on relief and reconstruction in Gujarat alone after the severe earthquake of January 2001 has been about Rs. 11,500 crore in that year. Thus it is evident from the facts and figures that for the national development and citizen‟s welfare, development process needs to be sensitive towards disaster prevention and mitigation aspects. There is an urgent need to look at the disasters from a development perspective.
India‟s unique geo-climatic position makes India particularly vulnerable to natural disasters. India is a vast peninsula of sub-continental size and surrounded by sea on three sides and has the Himalayas range on the fourth side, which has some of the tallest mountains of the world. That is why India has to face a very large variety of disastrous events of geological, oceanic or climatic origin. There is a broad classification of natural disasters in India. Brief description is mentioned below as per the geological origin of these disasters.
North India comprising the Himalayan mountainous region and the Indo-Gangetic plains ahs highly variable topography with some of the tallest mountains and perennial rivers. Its northern most boundary also happens to be the zone of collision of two major tectonic plates, viz. the Indian plate and the Asian plate. The area also has many geological faults. North India is also characterized by spells of hot, cold and rainy weather and attributes can vary within wide limits creating unusual situations. As a result of these characteristics geographical, climatic, and geological features, North Indian states (J&K, HP, Punjab, Haryana, Uttaranchal, Delhi, UP, Bihar) are visited by natural disasters in the form of earthquakes, landslides, avalanches, floods, droughts, heat and cold waves.
The location and climate of East and North East India (WB, Sikkim, Assam, Arunachal Pradesh, Nagal and Manipur, Meghalaya, Tripura, Mizoram) are such that these states are visited by earthquakes, landslides, floods, and droughts. West Bengal can be affected by cyclones also.
The central parts of the country (Orissa, Chhattisgarh, Jharkhand, M.P, Rajasthan, Gujarat, Maharashtra and Goa) have a highly variable rainfall regime, both in time and space. Therefore, floods and droughts are major disasters in the area. Orissa and Gujarat suffer heavily from cyclones. Goa and Maharashtra suffer from very heavy rain fury. Orissa has also suffered from heat waves in recent years.
The peninsular India (Andhra Pradesh, Karnataka, Tamil Nadu, and Kerala) suffer mainly from cyclones, floods and droughts. While Kerala escapes the fury of cyclones, it suffers from earthquakes and landslides in addition to floods and droughts. The Telangana and Rayalaseema area of Andhra Pradesh are highly rain-deficient areas and therefore suffer drought conditions often.
Among the Island groups, Andaman & Nicobar Islands are vulnerable to earthquakes, heavy rains and occasionally cyclones. Andaman Islands also have two sleeping volcanoes i.e. Narcondam and Barren Island.
The Lakshadweep Islands are coral islands and therefore are only a few centimeters above the sea level. They could be threatened in case of significant sea level rise due to the global warming. This could threaten some of the India‟s biggest cities like Kolkata, Chennai and Mumbai, which are commercial hubs.
Winter season (December, January & February)
During these months, Himalayan range receive copious amounts of rain and snow and the weather phenomenon known as “western disturbances” also brings in strong winds with rain, which at time can be heavy. Hence, the mountainous areas of north India are prone to snow avalanches and landslides. In the aftermath of rainy spells in this cold season, one or two spells of cold waves occur usually. Heavy fog creates aviation hazard, and hail damages crops and orchards in the plains of north India.
Pre-monsoon or Hot weather season (March, April and May)
Cyclones take shape over the Bay of Bengal and the Arabian Sea and move westward or northwestward. Thus the eastern coast is more vulnerable to cyclones and accompanying storm surges. The cyclones that generate in the Arabian Sea move west or northwestwards, thus sparing the west coast but pose serious risk to the oil exploration outfits in the Arabian Sea. If a cyclone recurves, it affects Gujarat adversely and gives considerable rains in Rajasthan as well and creates floods sometimes.
Monsoon season (June to September)
This is the flood season for the entire country and floods occur wherever monsoon becomes more active. Conversely, the areas where the monsoon remains weak, suffer from drought in this season. Landslides are a common feature in the hilly areas of Himalayas from J&K to the northeastern States. Landslides also occur in the Western Ghats and in the hilly areas of Kerala in this season.
Post-monsoon season (October, November)
This is again a cyclone season when cyclones generate in the Bay of Bengal and Arabian Sea and move west or northeastwards in the same general fashion as in the pre-monsoon season. But the cyclonic activity is usually more pronounced in this post monsoon season as compared to that in the pre-monsoon season. This is also the season when the southern states of Andhra Pradesh, Karnataka, Tamil Nadu, and Kerala receive considerable rainfall from the northeast monsoon, and are therefore vulnerable to the threat of floods.
Disasters are sudden and intense events which result in considerable destruction, injuries & deaths, disrupting normal life as well as the process of development. Disasters are perceived to be on the increase in terms of their magnitude, frequency, and economic impact in India. It has been emphasized that a disaster retards the development process in the affected area and extends to the neighbouring regions also. Various types of natural disasters that occur in India like Earthquakes, Volcanic eruption, Landslides, Snow Avalanches, Tsunami, Cyclone, Floods, Drought, heat & cold Waves, sea Level Rise, Gl0bal warming, Ozone depletion have been described very briefly and the regional and seasonal profile of their occurrence have been outlined. Seasonal profile briefly describes four different seasons of India like Winter season covering December, January & February; Pre-monsoon or Hot weather season which include March, April and May; Monsoon season that lasts from June to September; and finally Postmonsoon season covering October & November.