State hydrologists expect downpour from typhoon Lando (international name ‘Koppu’) to bring water reserve in Metro Manila’s rain-fed main water source Angat Dam closer to the 210 meters target flood season high water level (FSHWL) there.
“Our calculations show such downpour can result in a four-to eight-meter rise in Angat’s water level which was at 194.16 meters only as of 6 a.m. Saturday,” said Richard Orendain, senior hydrologist at state weather agency Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa).
He noted such rise might be possible if Lando dumps heavy to intense rain while remaining stationary for several hours after it makes landfall in Aurora province but before heading northwards to extreme Northern Luzon.
“If such scenario happens, it’ll be good news for Angat,” he said.
What’s ideal is for Angat Dam’s water level to at least reach the FSHWL by yearend to better ensure availability of water for the following year, he noted.
Data show as of 6 a.m. Saturday, Angat still needed 570 millimeters of rain so its water level can reach the FSHWL, however.
Authorities said lack of precipitation due to the prevailing strong El Nino phenomenon is hampering rise in Angat’s water level, affecting availability of reserve there.
In its 11 a.m. severe weather bulletin released Saturday, Pagasa warned of heavy to intense rainfall within the 600-kilometer diameter of Lando.
“The typhoon covers a wide area so we expect Angat watershed to still receive rain from Lando even if this typhoon will likely landfall in Aurora,” Orendain said.
Pagasa forecast ‘Lando’ to make a landfall Sunday morning in Aurora along Luzon’s eastern seaboard.
According to Pagasa, Lando was 295 kilometers east of Aurora’s Baler municipality as of 10 a.m. Saturday.
Lando packed maximum sustained winds of 160 kilometers near its center and gustiness of up to 195 kilometers per hour, Pagasa said.
“That typhoon slightly intensified,” said Pagasa.
Pagasa also forecast Lando to head west at 10 kilometers per hour.
The agency expects ‘Lando’ to likely move through Northern Luzon during the weekend then exit this area’s west coast-lying Ilocos Region around Tuesday (Oct. 20).
Orendain said this Saturday morning, Angat watershed already began receiving moderate rain from Lando.
“More rain there will mean more water for Angat Dam,” he said.
He noted Angat hasn’t received much rainfall in previous days, resulting in no significant water level rise there.
“Rain there then was mostly from thunderstorms only,” he said further.
In mid-2015, government stopped supplying Angat water for irrigation to help ensure availability of this commodity for Metro Manila.
Government then also began reducing allocation of Angat water for Metro Manila as Pagasa expects El Nino to last until mid-2016.
Earlier, Pagasa forecast El Niño to intensify further – possibly to a new record high. PNA