Natural Hazards And Disasters

While all Bihar and West Bengal also experience flooding during monsoons, the extent of flooding is greater in Assam. Brahmaputra floods its banks annually, causing massive disruption in the lives of the people in the region. The major reason for this is the lack of India-controlled dams on the river.

D. Pithorgarh

Explanation: in 1998, the massive landslide in Pithorgarh district wiped off the village of Malpa altogether. It blocked the flow of Sharda river, and caused massive destruction. The landslide was caused by massive unplanned construction on the weak soil along the river-bed.

Tamil Nadu experiences heavy precipitation in the post-monsoon period, due to north east monsoons (retreating). These originate in the Bay of Bengaland move north-east to southwest. Hence, they deposit most of their moisture over Tamil Nadu, causing floods in winter.

Brahmaputra has a braided channel, with several riverine islands across its length. Majuli is the largest inhabited riverine island in the world.

Hazards are circumstances in the environment which have the potential to cause harm to the people. When this damage is realized on a large scale, causing loss of life and property, it turns into a disaster.

There is a northward drift of the Indian plate, which is constrained by the presence of Eurasian plate. The young mountains of Himalayas accumulate energy at various points along their length, and periodically release this as earthquakes.

Developmental activities can trigger natural disasters over longer periods of time. These include:

• Development of port towns on the shores of the country make the people susceptible to disasters like cyclones and hurricanes.

• Construction on slopes of the young mountains can trigger landslides by loosening the soil on the slopes.

• Agriculture and extensive ploughing on slopes can also cause landslides

• Massive construction of roads is associated with floods and water logging, due to lack of percolation of water into the earth.

A cyclone is formed when following factors are present:

• Warm moist air, to provide latent heat through condensation.

• Coriolis forces

• Local disturbances in an unstable troposphere

• Absence of strong vertical wind wedge

Eastern India floods are more frequent, and are caused by overflowing of rivers. In the western parts, the floods are generally associated with excessive rainfall and accumulation of water in low-lying areas (flash floods).

Central and Western India is prone to droughts because the rain bearing winds lose their moisture by the time they reach the central parts of the country. Also, there is a lack of relief features to intercept the winds and cause precipitation.

Landsides are a major natural disaster in India, causing massive damage to life and property in the country. The following areas are most prone to landslides:

• Very Highly Vulnerable areas: Himalayas, young mountains of Andaman and Nicobar Islands, high rainfall areas in Nilgiris and Western Ghats.

• Highly Vulnerable areas: Himalayan states and north-east India.

• Moderate to Low Vulnerable areas: Aravalis, Ladakh region of Himalayas, rain shadow areas of the Ghats.

Mitigation:

• Restriction on developmental activities viz. construction of roads, dams etc.

• Limiting agriculture to valleys.

• Promoting afforestation of slopes

• Terrace farming should replace shifting cultivation in north-eastern Himalayas.

Vulnerability refers to being exposed to harm from an adverse situation. India is vulnerable to droughts because of the unique climactic conditions in the country, and the poor dependability of monsoon rains.

On the basis of vulnerability, the following zones have been identified:

• Extreme Drought Affected areas: areas of Rajasthan to the west of Aravali, Kachchh region of Gujarat

• Severe Drought Prone areas: Eastern Rajasthan, Madhya Pradesh, interior parts of Andhra Pradesh and Karnataka Plateau, northern parts of interior Tamil Nadu and southern parts of Jharkhand

• Moderate Drought Affected areas: Northern parts of Rajasthan, Haryana, southern districts of Uttar Pradesh, the remaining parts of Gujarat, Maharashtra except Konkan, Jharkhand and Coimbatore plateau of Tamil Nadu and interior Karnataka

• Free or Less Drought Prone areas: Rest of the country

Mitigation:

• Provision of drinking water and medicines in the affected areas.

• Availability of fodder for cattle.

• Inter-linking of rivers to transfer excess water to drought-prone areas.

• Identification of ground water levels and their sustainability.

• Awareness about drought resistant crops.

• Rain water harvesting.