Cloud seeding over Angat Dam begins — report

The government on Thursday began a cloud seeding operation over Angat Dam in Bulacan – an uncertain mission to induce rain to raise the reservoir’s water level that has been below the critical point in past weeks. A radio dzBB report said officials from the Agriculture department’s Bureau of Soil and Water Management took to the skies on a Chemtrad aircraft loaded with some 500 kilos of "salt" made up of silver iodide and dry ice. The team was in constant coordination with a dam official on the ground, serving as a spotter who guides the plane to hit the clouds targeted for "seeding." The operation will last between two to three hours.

A member of environmental group Greenpeace shows how low water level at the Angat Dam in Bulacan has gone. Greenpeace

Usually carried out with the help of an aircraft, cloud seeding is done by spraying silver iodide and dry ice on clouds to stimulate and increase rain. Cloud seeding operations over Angat Dam, which supplies 97 percent of Metro Manila water needs, was canceled on Wednesday because rains brought by an intertropical convergence zone (ITCZ) came. The weather pattern, according to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), triggered rains over southern Luzon, the Visayas and Mindanao. Wednesday’s rains slightly raised the dam’s water level, which stood at 158 meters, or 22 meters below the critical point at 180. The Department of Public Works and Highways had already declared a water crisis in Metro Manila’s west zone served by Maynilad Water Services, Inc. Maynilad gets its water from Angat Dam and serves over seven million customers in Metro Manila and the municipalities of Bacoor, Imus, Kawit, Noveleta and Rosario in Cavite province. On Thursday, Public Works secretary Rogelio Singson said the government allotted funds for a 70-hour flying hours for cloud seeding operations. "And we will augment the budget [on cloud seeding] if needed," Singson also said in a press briefing in Malacañang that was aired over radio dzBB. A total of 117 villages in Metro Manila — mostly in Caloocan City, Quezon City, and Manila — currently experience interrupted water services that can reach up to six hours. Of these areas, 32 barangays have no water supply at all. Uncertain mission While the cloud seeding operation was still being proposed, PAGASA repeatedly gave reminders that seeded rain might not fall on watershed areas, such as the Angat Dam's location. Spotting the right clouds for the seeding mission would be difficult because satellite cameras often misses the right cloud forms. PAGASA forecaster Gener Quitlong said Thursday that satellite photos show only the high clouds. "You cannot see those at the middle level," Quitlong said in an on dzBB radio. According to him, meteorologists taking part in seeding operation should be able to spot clouds that are suitable for seeding. [See: PAGASA: 'Seedable' clouds not easy to spot] - Mark D. Merueñas, LBG, RJAB Jr., GMANews.TV