Typhoon Ulysses: less rain than Ondoy

FLOODED CITY The storm dumped heavy rains that caused the Marikina River to grow, which overflowed its banks and flooded communities near the waterway, forcing evacuations. —RICHARD A. REYES

Typhoon Ulysses (international name: Vamco) dumped less rain over a longer period of time over Metro Manila compared to Tropical Storm Ondoy (Ketsana), but thousands of storm-weary residents cannot help but recall painful memories of the 2009 disaster that plunged swaths of the metropolis into chest-deep flooding.

Data from the state meteorological service Administration of Atmospheric, Geophysical and Astronomical Services of the Philippines (Pagasa) showed that Ulises dumped less rain than Ondoy during his attack in Metro Manila, but a large volume of rain in the Marikina and Pasig rivers upstream and the storms that hit one. after another, from late October to early November, it could have affected the way the waterways swelled and flooded the metropolis.

356 mm of rain

Between Wednesday morning and Thursday morning, Ulises dumped 356 millimeters of rain in Tanay, Rizal, according to data from the Sierra Madre de Pagasa monitoring station over the city.

It was the largest volume of rain collected from Ulises, Pagasa climate specialist Ariel Rojas said Thursday.

“It is possible that the heaviest rains were seen [on] the mountains, which could have caused the flooding in parts of the Marikina river basin, ”Rojas said at a press conference.

Rain from previous storms “Quinta” (Molave), “Rolly” (Goni) and “Tonyo” (Etau) could also have affected the rapid rise in river water levels, although the previous three cyclones did not. made directly. hit Metro Manila.

“The soil is already saturated, so its ability to absorb water is already diminished,” said Rojas. “This means that the runoff has already gone directly to the rivers and downstream.”

Monitoring stations along the Marikina-Pasig river system collected an average of 234mm of rain in 11 hours, Pagasa said.

That volume was less than the rain collected at Ondoy, which averaged 330mm in just six to eight hours of torrential rain on September 26, 2009.

More rain from Ondoy

Forecasters said Ulysses was moving faster than Ondoy, who crawled through Luzon at 15 kilometers per hour. The slow movement of the storm allowed it to dump more rain as it crossed central Luzon and loomed over Metro Manila, they said.

“During Ondoy, there were heavy rains on both the Marikina-Pasig River and the Marikina-Pasig River,” Pagasa hydrologist Sheila Schneider told the Inquirer. “During that time, we had more rain in a shorter period of time.”

In Quezon City, Pagasa recorded 153mm of rain from Ulysses in a 24-hour period, much less compared to 455mm of rain collected from Ondoy in the same area.

But the rain poured by Ulysses in Quezon City exceeded the normal average rainfall of 148 mm that the city usually receives during November.

Even with less rain in Metro Manila, Ulises pushed the Pagasa monitoring stations along the Marikina-Pasig, San Juan and Tullahan rivers beyond critical levels since Wednesday night, or even before making landfall in Quezon province.

The monitoring stations in Montalbán and Burgos in the province of Rizal exceeded the critical levels at 9 pm on Wednesday, while those located in San Mateo in Rizal and Santo Niño and the Marcos Highway in the city of Marikina exceeded the critical point the early Thursday.

Deforestation

To determine the cause of the flooding in the metropolis, Schneider said it was also necessary to analyze the condition of the Upper Marikina River Basin, also known as the Upper Marikina River Basin, which could affect the flow of rainwater into rivers. that meander. Metro Manila.

Deforestation in the basin seriously contributed to the unprecedented floods that caused hundreds of victims in Metro Manila, but particularly in flood-prone areas in the cities of Marikina and Pasig, during Ondoy, he said.

“But one of the main differences now is that the public is more aware,” Schneider said, adding that even Pagasa updated its own warning tools and systems after the 2009 storm.

“Even local governments are now more informed about what to expect when a storm is coming,” he said.

After weeks of devastating storms, hit communities, especially on the east coast, may breathe a temporary sigh of relief as no weather disturbances are expected, at least for the next few days.

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