M. Malleswara Rao

Two research institutes adduce conclusive proof of success

  • Twin programmes a big push to agriculture
  • A.P. seeks aid to conduct experiment for a group of States

    Hyderabad: Water scarcity forced no fewer than a dozen countries to take to cloud seeding. But many of them have put the experiment on hold, thanks to the unprecedented rains of late, attributed to El Nino/global warming. Andhra Pradesh, nonetheless, conducted the experiment for the fourth consecutive year in 2006. Eighteen tmcft (thousand million cubic feet) of water, four times the full storage of Osmansagar, Hyderabad's principal water source, has been claimed as a gain from the latest round of cloud seeding that lasted till December 31. One tmcft can irrigate 10,000 acres.

    Rain shadow areas

    Winds are never weary along the 930-km coast of Andhra Pradesh, open to the ever turbulent Bay of Bengal that makes monsoon all the more vigorous. Cyclones batter the State with unfailing regularity, but 10 of its 23 districts turned rain shadow areas without sufficient rainfall. Anantapur is viewed as another Jaisalmer while Mahabubnagar is considered on its way to "becoming a desert."

    The State Government has adopted cloud seeding as a drought-proofing measure, while simultaneously implementing `Jalayagnam', a programme launched to construct 30 irrigation projects at a time to tap the unused waters of major rivers.

    The twin programmes aim at giving a big push to the "neglected agriculture sector," according to official sources. Two planes criss-crossed the skies to chase rain-bearing clouds. Guided by high-resolution radars installed in Anantapur and Hyderabad, the aircraft fired the flares (shots of the seeding material, calcium chloride/silver iodide) into warm clouds, usually at an altitude of 4,000 feet, precipitating rain.

    Critics termed the positive results mere "claims." The Centre for Atmospheric Sciences & Weather Modification Technologies (CASWMT), Jawaharlal Nehru Technological University, to which the programme has been handed over in the wake of the criticism against the Government doing the job itself and making claims, says 204 of the 242 flares fired during 300 flying hours through the 90-day period till December-end, yielded results an 84 per cent success rate.


    The CASWMT called the operation a success, quoting the standard expression used by weather modification scientists that, "seeding doesn't create rainfall but only enhances it by 15-45 per cent from a favourable cloud." It attributed 1,825 mm out of the 12,160 mm of rain received in the induced areas to seeding, limiting the enhancement, however, to a modest 15 per cent.

    The rainfall claimed under the experiment in 2005 was 47 tmcft a quantity equal to one-tenth of the storage in Nagarjunasagar.

    The claims got mired in a controversy with ambiguity surrounding the results. The CASWMT could not establish its claims beyond doubt owing to non-availability of rain gauges at all 6,000 induced villages in the 10 districts to collect droplets of artificial rain and test them for calcium chloride.

    Area-specific seeding ruled out

    Moreover, the rain that lashed the State through the two monsoons, obscured the minor gains. Often, precipitated clouds rained over desolate places providing random benefit, leaving out habitations that yearned for water.

    Area-specific seeding, as in China, has been ruled out by scientists for the present "in a poor country" in view of the huge investment required to engage many planes at a time to create artificial pressure and move the rain-bearing cloud over to a selected place. The experiment was not undertaken during nights "due to poor visibility," and it didn't cover "cold clouds."

    Despite the criticism from some quarters, the National Geophysical Research Institute and the Indian Institute of Chemical Technology have adduced "conclusive proof" of the success of the experiment, certifying the presence of calcium chloride beyond normal level in the artificial rains.

    This came as a morale booster to the CASWMT. Such certificates, issued earlier by the State Government's Environment Protection, Training & Research Institute, were sneered at by the critics.

    It was the U.S. which began cloud seeding in 1880, followed by a more systematic effort in 1946.

    Today, China, Israel, Russia, Canada, Australia, New Zealand, Thailand, Jordan, Argentina, South Africa and Mexico are using the technique.

    In China, 35,000 people and 800 institutions are involved in the experiment. They were able to fill Miyun and Chaobai, Beijings's main sources of drinking water, with artificial rains, it is said.

    In India, where the technique was first used in 1957, Karnataka conducted the seeding over the Lingana Makki reservoir in 1975, while Tamil Nadu in 1983 even purchased a separate aircraft for the purpose.

    After spending Rs 100 crore so far, Andhra Pradesh has sought the Centre's assistance to conduct the experiment for a group of States as a national policy experiment. The response is awaited.