What I am proposing here is not for storing water for agriculture or generating electricity. And certainly my proposal does not involve big dams. In fact, it is quite the opposite. Instead of raising the water level to a great degree and submerging the surrounding areas as it happens with big dams, I propose to go lower.
Have small check type of dams on small streams and rivulets which join a major river.
In the vicinity of this dam (it may range from few a hundred metres to 1-2 kilometres depending on the gradient) and at a suitable place dig a lake. Digging a lake is less costly and very, very feasible. Lakes can be anywhere from 50 - 200 acres.At the time of abundant rains, channel the water through an intake into this lake instead of letting all the water downstream. How to utilize this water is a choice that can be left to people living nearby.
They can use it for drinking, irrigation or just to increase the ground water table.
They can use it for drinking, irrigation or just to increase the ground water table.
Digging thousands of such lakes need not be a costly affair. It is certainly cheaper than several other methods adopted so far. By not letting all the rain water run into rivers and then the seas, we are also doing a better job of conserving water. More importantly, the impact of floods in downstream regions is reduced.
The investment in digging lakes can be recovered very quickly through savings that result from prevention of annual loss of property worth crores of rupees alone. Approximately 12000 K litres of water (a tanker is usally 10 KL)can be stored in an area of one acre 10 ft depth and the cost of digging an acre would be Rs. 15 lakhs. Digging of such lakes can be a part of Rural Employment Guarantee Scheme.
The investment in digging lakes can be recovered very quickly through savings that result from prevention of annual loss of property worth crores of rupees alone. Approximately 12000 K litres of water (a tanker is usally 10 KL)can be stored in an area of one acre 10 ft depth and the cost of digging an acre would be Rs. 15 lakhs. Digging of such lakes can be a part of Rural Employment Guarantee Scheme.
Suggestion 2
Increase the capacity of our rivers, streams, canals and lakes.
Because of excessive deforestation and occupation of floodplains over the past 100 years, our rivers, streams, canals and lakes have become heavily silted thereby reducing their water-bearing capacity drastically
As a result one week of rain is enough to cause most of the rivers in India to flood. If a massive desilting operation is undertaken during summer season , it could double the water-bearing capacity of these water bodies. Then it will take that many more days for these water bodies to swell.
The few extra days are enough to limit the damage caused by floods to a great extent. A river of length of 500 KM can be dug deeper by another 10 ft at an approximate cost of Rs.1000 crore. The cost for the same is estimated at Rs.40 for one cubic yard of material dug out.
I agree these two ideas are nothing new. People have been advocating these ideas in one form of or the other. Here, I am suggesting these ideas solely with the aim of preventing floods. Irrigation and increase of ground water table are added benefits of these measures. It is worth spending some money on preventing floods than incurring heavy losses later because of them.
2 comments:
It is tempting to make policy on the basis of minimum or imagined facts, but in my experience, policies have to be robut - that is, failure-proof - and you can't make them so without looking at facts on the ground. The reason why floods are so widespread in the lower Gangetic plain is that the land is very flat and there is not much of a slope. Your idea of retention ponds is impracticable in most places because a very high proportion of the land is being used. To recommend dredging without looking at the volume of water to be carried during a flood is naive. Altogether, well meaning but not good enough.
I agree with you that Gangetic plain being flat is one of the reasons for frequent cause of floods. At the same time embankments coming in on either side of the rivers leaving no flood plains is one of the reasons why so much of damage gets concentrated at few places. Flood plains act as natural leeves. Not only that in good old days when flood plains were there much of the silt used to get deposited during flood in the flood plains. Now that it gets settled in the river beds itself
Flood plains being no longer there in most of the places we need to increase the capacity of water bodies.
And I genuinely felt digging is a good alternative vis-a-vis living with damage caused by frequent floods.
And coming to retention ponds, if we are not willing to dig them, other alternative is to have dams. Dams in a way are contributing to intensity of floods. When level reaches the danger mark in dams because of incessant rains flood gates are raised often causing even more damage to downstream areas where they could have been already flooded because of incessant rains.
No river is mighty at the place of its birth. By not letting all the water into them the extent of damage of floods can be mitigated to far greater extent. I am not sure about rest of India but in AP in several places artificial lakes can be still constructed. Even in plains through out the course of river the terrain is not flat and does not slope in one direction and that is why rivers meander.
I understand the cost of constructing these lakes versus bearing with the cost of flood damage need to be studied further.
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