IRRITANT Heavy rains and high tide result in flooding in a section of Barangay Poblacion in Guiguinto, Bulacan. —CARMELA REYES-ESTROPE
Heavy rains brought by Tropical Depression “Nika,” alongside the southwest monsoon, on Sunday led to a 2-meter rise in the water level of Angat Dam, the highest increase recorded in the past week, the weather bureau said on Monday.
The dam supplies 90 percent of Metro Manila’s water needs.
Monitoring by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) showed that the water level in Angat’s watershed rose from 179.59 meters above sea level (masl) from Sunday morning to 181.98 masl on Monday morning, an increase of 2.39 m.
Despite the rise, however, it was far from the dam’s normal high level at 210 masl.
It was also far from the rule curve elevation, or the minimum reservoir level that should be maintained to ensure enough water supply in the drier months, said Max Peralta, Pagasa senior hydrologist. For Angat Dam, the rule curve elevation is pegged at 190.25 m.
“At this point, we really cannot say that it is already at its normal operating level,” Peralta told the Inquirer.
“By December, the reservoir should already be filled so that there would be enough supply in the lean months,” he said, adding that the dam’s current water level was at its lowest compared to those in the past few years.
Other dams in northern Luzon, including Ipo, La Mesa, Ambuklao, Pantabangan and Magat, also recorded an increase in water levels on Monday.
10 villages submerged
In Bulacan province, 10 villages in four towns were submerged in floodwater that reached up to 4 feet after Ipo and Bustos dams released water on Sunday due to strong rains, the provincial disaster risk reduction and management office (PDRRMO) said.
Ipo released water at 144 cubic meter per second (cms) when its level reached 101.70 masl, slightly higher than the 101.00-masl spilling level. The excess water flooded low-lying villages in Bocaue, Baliwag, Bustos and Marilao towns.
Bustos also released up to 106 cms when its elevation reached 17 masl. Its spilling level was 17.34 masl.
Bustos Mayor Francis Juan said the floods had forced six families in Barangay Catacte to evacuate. They were allowed to return home on Monday morning when the rains stopped.
Low-lying villages in Guiguinto, Balagtas and other areas were also hit by floods. The PDRRMO said the floodwaters had subsided on Monday morning, but Ipo and Bustos dams continued to release water in the afternoon.
Overflow bridges
In Isabela, five overflow bridges were temporarily closed to traffic on Sunday after continuous heavy rains left major rivers and tributaries in the province swollen.
Jimmy Rivera, head of the Isabela PDRRMO, identified the bridges as Baculod in Ilagan City, Alicaocao in Cauayan City, Turod-Banquero in Reina Mercedes town, Gucab in Echague town, and Cabagan-Sta. Maria and Sto. Tomas-Cabagan in Cabagan town.
In Zambales province, 15 people, including two children age 3 and 8, were rescued on Monday after they were trapped in the swollen Dapya River in Cabangan town. They had gone swimming in the river on Sunday.
Rains were expected to continue on Tuesday, even as Nika has already exited mainland Luzon. As of 3 p.m. on Monday, it intensified to a tropical storm (international name: “Nangka”), as it moved west-northwest at 20 kilometers per hour.
Pagasa is also monitoring a low pressure area at 530 km east of Surigao City in Surigao del Norte province. The weather disturbance is expected to bring scattered rain showers and thunderstorms over Davao Oriental, Dinagat Islands and the Surigao provinces.
The southwest monsoon will also bring scattered rainshowers over Metro Manila and the Ilocos, the Cordillera, Central Luzon, Calabarzon regions, and Cagayan, Isabela, Nueva Vizcaya, Quirino, Palawan and the Mindoro provinces.
—Reports from Jhesset Enano, Carmela Reyes-Estrope, Villamor Visayas Jr. and Joanna Rose Aglibot