Flood decontrol

Every action has an opposite and equal reaction. If you embank a river it bursts its embankments. So much for flood control measures

 
Published: Saturday 04 July 2015

WE ALL live downstream when it comes to facing hardships. People upstream usually create problems for those living downstream. If water laden with pesticides makes its way into the Yamuna and ends up in the livers and body fat of the literati and glitterati of the nation residing in Delhi, we can blame the farmer in Haryana. It is because of his unrelenting dependence on chemical farming that agricultural run off contains toxic chemicals in the first place. If there is a water shortage in New York city it is because communities upstream do not wish to share their water with those downstream, perhaps rightfully so. But if there are floods in India we cannot lay the blame at Nepal's doorstep merely because we live downstream.

Indian Prime Minister Atal Behari Vajpayee nearly did so. He is not to blame. He is simply ignorant. It is commonly believed that flood control measures taken upstream will solve the problem downstream and that deforestation in the hills is responsible for floods in the plains. If only this were true it would be very easy to do away with floods. Unfortunately, it is not true.

Speaking recently in Gorakhpur after a visit to the flood-hit areas of eastern Uttar Pradesh, Vajpayee told the press that India will take up with Nepal the perennial problem of floods in northern parts of the country, as most of the rivers originate in the Himalayan state.

It seems that during his recent visit to Durban, to attend the non-aligned summit, Vajpayee impressed upon his Nepalese counterpart the need to expedite flood control measures upstream. But in dealing with nature, prime ministers tend to forget that even though they can steamroll engineering responses to floods, they might not be able to "order" away floods.

Floods are and will continue to be an inherent feature of the plains of north India. Whether the Himalayan mountains are well-clad with green cover or balding, it will make little difference.

The process of erosion is so intense that it dwarfs the changes caused by deforestation. Afforestation may help the local economy of the hill states but it will not be able to prevent large floods. The Himalaya are the youngest fold mountains in the world. Their ecological constitution is extremely fragile. The nature of the rock is weak and friable. The rainstorms which lash the region are more vicious than rainstorms any other mountain system has to face. The Himalaya are also highly seismic. Some of the world's worst earthquakes have occurred here.

The mighty Himalayan rivers carry water and silt in explosive waves. The millions of tonnes of silt that they have carried down over the ages, has led to the formation of the Gangetic plain. Rivers frequently change their courses and flood periodically. The Kosi in Bihar has travelled 100 kilometres westward in the last 200 years. The Teesta which flows through the Sikkim and Darjeeling mountains is possibly the wildest river in the Himalaya. After the destructive floods of 1787, the river, which used to flow into the Ganga, changed course and started flowing into the Brahmaputra. Trying to tame these rivers will be as effective as to standing on the beach and ordering the ocean waves to roll back.

The 15,000-odd glaciers which cover about 17 per cent of the mountain area - as compared to only two per cent in the Swiss Alps - are retreating today. This progressive retreat is leading to the formation of moraine dammed lakes which eventually burst and send a flood pulse down the river. One such lake, the Dig Tsho burst in Nepal in August 1985 following an avalanche from the Dig Tsho glacier. The flood pulse raced down 80 km in the Bothe Kosi and the Dudh Kosi destroying 14 bridges, hundreds of trees and several buildings.

Even if Nepal were to go in for a wide array of engineering responses to curb floods and set up dams in a highly seismic area under international pressure it will fail to put an end to floods.

Such measures have been a failure in both India and China. Dams have contributed to floods in both countries and embankments have imparted a false sense of security, leading to encroachment of the flood plain area. When a breach occurs a tidal wave of water hits the villages and townships nearby. Embankments also disrupt the natural drainage of the land and hinder the retreat of flood waters prolonging flooding and water-logging. They also promote the incidence of water-borne diseases. Flood damages have actually increased after embankments were set up in India.

Therefore, people downstream will have to learn to live with floods and plan their lives accordingly. Flood plain zoning - avoiding settlement in the flood plain area of a river - is one such answer.

The ancients always built settlements near rivers but on high land and never encroached upon the flood plain area of the river. They welcomed the floods for they enriched the soil and the end result was a bumper harvest.

Today humans have built walls between themselves and rivers. By cutting themselves off from nature they have deprived themselves of the fruits of nature and have now to face its wrath.

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