Vol. 3	No. 1	Februray   2001

The Centre for Science and Environment (CSE) has been working on the issue of community-based water management and water harvesting for over a decade now and strongly believes that it is possible to make the country completely drought-proof in ten years through water harvesting. A survey conducted by CSE of several villages facing drought in Gujarat and western Madhya Pradesh found that all those villages which had undertaken water harvesting and/ or watershed development in earlier years were able to sustain themselves much better than the neighbouring villages which had failed to do so.

What makes rainwater harvesting such a powerful technology?
Just the potential of a few millimetres of rain. For example, Barmer district in Rajasthan, one of India’s driest places, receives 100 mm of water in the year. If this rain falls on one hectare of land, the total rainwater received is as much as one million litres - enough to meet drinking and cooking water needs of 182 people at a liberal 15 litres per day. Even if a portion of water is captured, the villagers could still with rudimentary technology, collect at least half a million litres a year. In fact, there is no village in India that can not meet its basic drinking and cooking requirement through water harvesting.

The strategy for drought-proofing should be to ensure that every village captures all the runoff resulting from the rain falling over its entire land and storing it in tanks or ponds or using it to recharge the depleting groundwater. It would then have enough water in its tanks or in its wells to cultivate substantial lands with water-saving crops like millets and maize.

Water in Tildeh's check dam: projecting the potential of a cohesive effort

Drought-proofing versus large-scale irrigation Drought-proofing and large-scale irrigation development are not substitutes for each other, simply because what one can do, the other cannot. Even after all the proposed dams are built to promote large-scale irrigation development and interlinking of rivers takes place, not every piece of the country’s cultivated land will see the benefit of canal irrigation. These lands will have to depend either on groundwater or local water harvesting. These two will also have to go together because heavy use of groundwater can only be sustained if there are local efforts to keep recharging the groundwater. Therefore, large-scale irrigation development is no substitute for drought-proofing based on local water harvesting systems and sustainable use of groundwater. Small means even more water Let us look at the relevance of village-based water harvesting from yet another point of view. The key component of water management is ‘storage’ especially in a country like India where the monsoon gives us on average about one hundred hours of rain and then nothing for the remaining 8,660 hours in a year. This water can be captured in: a) Large reservoirs with large catchment by building large dams; b) in small tanks and ponds with small catchment; or, c) by storing it in a way that it percolates down into the ground and gets stored as groundwater. In fact, there is strong scientific evidence to show that village-scale rainwater harvesting will yield much more water than big or medium dams, making the latter an extremely cost-ineffective and unscientific way of providing key water needs especially in dry areas. Some very instructive lessons can be learnt from the work of Israeli scientist Michael Evenari. He made an effort to reconstruct the ancient farms of the Negev, Evenari came up with a very surprising finding: Water harvested from small watersheds per hectare of watershed area was much more in quantity than that collected over large watersheds. While a 1 hectare (ha) of watershed in the Negev yielded as much as 95 cubic metres (cum) of water per ha per year, a 345 ha watershed yielded only 24 cum/ha/year. In other words, as much as 75 per cent of the water that could be collected was lost. The loss was even higher during a drought year. But Evenari was finding that even if you have the same amount of land you would collect more water if you break up the land into many small catchments than if you collect water from it as one catchment. All this means that in a drought-prone area where water is scarce, 10 tiny dams with a catchment of 1 ha each will collect much more water than one larger dam with a catchment of 10 ha. It should not be surprising that the large number of medium-size dams that have been constructed in Saurashtra stored very little water in this drought year and started going dry by December 1999. But then the answer to drought proofing of the area lies not in mega-water harvesting projects with medium and large dams. It lies in small water harvesting structures that are constructed at the farm and village-level.