Should cultivation be banned on hill slopes with gradient of over 30°?

Yes, because hill slopes are never good for cultivation of seasonal crops; they are okay for plantation and horticulture but even in such cases it is necessary to ensure that these are not practiced on steep slopes. That's because the topsoil in most hill slopes is very thin, not exceeding a couple of feet. Such hill slopes can't be left bare of agricultural land in the plains because during the rainy season the water run-off is much faster on hill slopes than it is in the plains.

As a result, any hill slope that doesn't have the protective cover of vegetation over it gets eroded by rainwater rushing down and washing away the topsoil. Depending on the intensity of rainfall in a particular area, the topsoil on hill slopes can get completely eroded in just 2-3 years at the end of which, rocks of the hills will appear as the new surface of the hill slope.

Erosion of Topsoil

The chain effect of such erosion of topsoil of the hills can be disastrous not just within the hilly region but even downstream on the plains. As the topsoil of the hills is washed onto the plains they accumulate in the river bed in the form of silt and gradually start choking the free flow of the river.

Seasonal Flooding

In a few years, the silt formation increases and small islands are formed on the river further choking the flow of the river. The most dangerous outcome of this process of silting on rivers in the plains is flooding on a massive scale that often increases the catchment of the river. Most of the flooding that takes place in India is due to severe silting of rivers.

The most common example of such seasonal flooding can be seen in the districts of North Bihar bordering Nepal. Many of the tributaries of the River Ganga from the Himalayan foothills in Nepal flow through this part and have been flooding the region for generations.

These days, due to the media focus we at least get to know about these floods that submerge almost the whole of North Bihar for months. Before the proliferation of TV channels in India, these massive floods were not even reported let alone becoming front page news. People passing through this region even after the rainy season would speak of a "sea-like view" as far as the eye could see.

Big Rivers, Huge Impact

The causes are easy to see in the rivers that flow north-south through this region from Nepal before meeting the Ganga on her east-west course. The actual cost of such flooding over such long spells is known only to the people of this region. The situation is quite complicated because this region is among the most backward parts of Bihar, a state which itself is the most backward state in the country.

On the other hand, Nepal, from where the rivers originate is among the most backward countries of the world with a growing rural population that is denuding the mountain slopes for agriculture. It's actually Nepal that must do something to check or at least slow down the rate of soil erosion but the poor country is caught up between her development priorities and this kind of environmental issues.

Updated on: 26-Jun-2020


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