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Cloud seeding fails, water crisis looms: DNA

Last Updated: Monday, August 10, 2009 - 09:46

Mumbai: Rain gods, it seems, are not smiling on the civic body. Inducement, too, has failed to appease them.

While it has not been raining enough in catchments to replenish the reservoirs, the civic body`s attempts to revive the "slack" monsoon by cloud seeding have not met with much success either. Since August 7, three of the four experiments carried out by the Brihanmumbai Municipal Corporation`s (BMC`s) hydraulic department in Tansa and Modak Sagar reservoirs have failed.

In the experiment, silver iodide crystals (250 gm for each attempt) are vaporised using a furnace on the ground. The vapours rise and fuse with the clouds. Since super-cooled (below freezing point) droplets in the upper regions of the clouds cause precipitation, silver iodide crystals encourage the growth of such ice particles, inducing rain.

Yet three experiments carried out on Saturday and Sunday induced no rain. Civic engineers associated with the weather modification project, however, claim that the fourth experiment conducted on August 7 caused 16mm rain.

Interestingly, while the experiment was conducted near the Tansa dam, precipitation occurred around 22km away at Modak Sagar.

Rain expert Shantilal Meckoni, roped in as consultant for the seeding project, said, "The wind velocity and direction caused the disbursement of the seeded clouds."

Deputy hydraulic engineer Pramod Guhe said it rained for three hours after the experiment. "No rains were witnessed before or after that. This has led us to infer that cloud seeding resulted in the rain," he said.

Guhe, however, agreed that there was no scientific mechanism to determine the results of cloud seeding.

But the failures have not deterred the hydraulic department, which plans to make 16 more such attempts to induce rain.

Besides, permission from the civil aviation ministry is expected in a day or two for the aerial experiment, for which Hyderabad-based firm Agni Aviation has been roped in.
During deficient monsoon in 1992, the BMC had conducted seeding experiments for nine days, inducing some rain on all days.

First Published: Monday, August 10, 2009 - 09:46
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