Cloud seeding underway, but where are the clouds?

MANILA, Philippines - Clouds suitable for seeding operations to bring rain to ease Metro Manila’s water shortage are not easy to find since satellite cameras often miss the right cloud formations, GMANews.TV reported yesterday.

Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) forecaster Gener Quitlong said satellite photos of cloud formations are not accurate indicators of the right conditions for cloud seeding.

“The satellite will show the clouds, but it’s best if you are on site. Satellite photos show you only the high clouds,” Quitlong said in Filipino in an interview on dzBB radio.

He said that meteorologists taking part in seeding operations should be able to spot clouds that are suitable for seeding.

Despite Pagasa’s warnings that rains from seeded clouds may not fall on watershed areas such as the Angat dam, the Bureau of Soils and Water Management (BSWM) and water concessionaires are set to go on with cloud seeding operations.

Angat dam, whose water level has been below critical over the past weeks, supplies most of Metro Manila’s water needs.

Angat cloud seeding starts

The first cloud seeding sortie of the BSWM over the Angat watershed finally pushed through yesterday afternoon.The operations were delayed for one day as BSWM personnel and several light airplanes were waiting at the Plaridel Airport in Bulacan when cloud seeding operations over Angat were canceled because of rains brought by an intertropical convergence zone (ITCZ).

Wednesday’s rains slightly raised the dam’s water level, which stood at 158 meters, or 22 meters below the critical point of 180. 

The Department of Public Works and Highways had already declared a water crisis in Metro Manila’s east zone served by Maynilad Water Services, Inc.

Cloud seeding started after BSWM experts finally spotted at 2 p.m. yesterday thick clouds over the southeast portion of the 63,000-hectare Angat watershed.

Officials of the Angat Dam said that water elevation has climbed to 158.75 meters above sea level.Blessie Concepcion, a representative of the BSWM that is attached to the Department of Agriculture (DA), said they finally spotted enough seedable clouds to start operations.She said that a total of 300 kilos of salt had been sprayed over the Angat watershed, which is part of the 1,200 bags of salt delivered by a container truck at the Plaridel Airport.The salt was sprayed over thick cumulonimbus clouds near the Angat watershed to create rainfall that will replenish the dwindling water reserve at the dam that supplies 97 percent of Metro Manila’s potable water requirement.Concepcion said that their operations were delayed by lack of seedable clouds.“Once our spotter spots enough clouds, we are ready to fly,” she said, noting that they have spotters stationed near the watershed surrounding the giant water reservoir.Concepcion said that BSWM is ready to conduct 70 hours of cloud seeding operations over the Angat watershed alone.The National Water Resources Board (NWRB) technical working group decided to ask the Metropolitan Waterworks and Sewerage System (MWSS) to fund the cloud seeding operations over Angat after the water level at the dam dipped to an all time low of 157.54 meters above sea level on Wednesday last week despite the onslaught of typhoon Basyang.The MWSS released P3 million for the cloud seeding operations.Rodolfo German, the general manager of the Angat River Hydro Electric Power Plant (Arhepp) of the National Power Corp. (Napocor), is not convinced of the effectiveness of cloud seeding.He said that it sometimes does not help as seeded clouds are blown away by winds, and rains would fall in places outside the watershed.Presidential spokesman Edwin Lacierda drew flak from Bulacan environmentalists when he said on a live radio interview yesterday morning that only Angat dam in Norzagaray, Bulacan is having problems with low water elevation, while La Mesa dam in Novaliches, Quezon City has enough water.Members of the Sagip Sierra Madre Environmental Society Inc. (SSMESI) said that Lacierda should get his facts straight.They noted that over 80 percent of water at the La Mesa dam is coming from Angat dam through the Ipo dam.“He should check his map and see the connection between the dams that supplies water to Metro Manila,” a SSMESI member said.The SSMESI said that water from Angat dam flows through Angat River to Ipo dam, which is connected by a pipeline to La Mesa dam, then to Balara Filtration Plant in Quezon City.  

Meanwhile, Pagasa said an intertropical convergence zone (ITCZ) might still bring rains to southern Luzon, the Visayas and Mindanao.

Pagasa said “above normal rains” are likely to prevail over the country in the next two weeks.

However, the weather bureau refused to recommend the termination of the cloud seeding operations being conducted over Angat despite the expected rains.

“In the next two weeks we will experience above normal rains due to the intertropical convergence zone and a low pressure area,” Pagasa senior weather forecaster Robert Sawi said in a phone interview.

He said the whole country would experience mostly cloudy skies with scattered rain showers and thunderstorms.

Sawi also could not say if there were “seedable clouds” over Angat, saying that Pagasa has no weather station covering the area.

He said the persons who conduct the cloud seeding operations usually are the ones who survey the area to determine if there are seedable clouds.