The World Bank Institute’s Water Policy Reform Program (1999) tells us that over 80 countries, with 40 per cent of the world’s population, are already facing water shortage, while by year 2020 the world’s population will double. The costs of water infrastructure have risen dramatically, and the quality of water in rivers and underground has deteriorated due to contaminants from cities, industry and agriculture. Time has come to devise innovative means to conserve water for future generations. Though sustainable models like rain water harvesting and drip irrigation should be reinforced, another ideal solution would be to utilise the water resources which go waste into the sea.

Rain fed rivers discharge a phenomenal amount of fresh water into the Bay of Bengal to a tune of 126x1010m3 every year and the Arabian Sea 29.7x1010m3/year, without being utilised for constructive purposes. With pressure on land being acute, constructing dams to conserve the discharge is not possible. The best way is to perhaps make optimum use of the gradient and the banks that border the river to store water by constructing a series of mini over-flow concrete gravitational dams of 10 to 20 metres height which commence from the river mouth and proceed upwards.

To enable such mini dams, the embankment along the banks should be raised to the extent of one metre higher than the dam along the gradient till it tapers off to zero height so that this dam can hold on to the substantial amount of water. The mini over-flow dam should also have sluices for regulating the movement of silt during the peak period so that the base of the dam is not silted nor the nature of the river flow tampered.

Indian peninsular rivers have a gradient of 20 cm/km at the mouth of the river, 40 to 280 cm/km based on the terrain through which it flows. An average of 200 metres width of the river can be used to construct a 10-metre dam for a river with a gradient of 20 cm/km. To do this, the embankment has to be raised by 10 metres which would taper to zero height at 50 km point of the river. The storage capacity of one such dam would be to the extent of 5x107 cubic metres per year. Similarly, for 40 cm/km gradient rivers, the embankment has to be raised by 10 metres which would taper to zero height at 25 km point of the river. At the zero point another mini over-flow dam of 10 metres height can be constructed and the series can continue throughout the length of the dam based on the river structure and its tributaries.

The benefits which will accrue are multifarious. There will be an enormous increase in the ground water on either side of the banks. If the water is stored at a particular height, a gravitational irrigation system can be evolved based on the capacity and requirement. It will also provide portable water to all in the villages along the banks.

River banks can be constructed along the river flow which will not disturb the river ecology and prevent flooding of the area. These mini dams can also be constructed on the banks of all tributaries that feed the major rivers that lead to flooding of various deltas. A river water transport system can also be evolved.

The Mahatma Gandhi National Rural Employment Guarantee Scheme could be used for de-silting during the dry season for maintenance of the banks. De-silting, in fact, could lead to scientific sand mining. Agrarian population on either side of the river can be given employment for raising the mud field embankment and also the responsibility to maintain it. Through this innovative method only the excess flow will be tapped and, hence would not trigger any inter-state disputes as the work progresses with the construction of the dam from the river mouth, upwards.

( K. Saleem Ali is special director, Central Bureau of Investigation and part time research scholar at I P University. He has submitted the above proposal to the government .)