Five days' worth of rain swamped QC in an hour, causing flooding, expert says

MANILA, Philippines — A total of 141 millimeters (mm) of rain, equivalent to five days' worth, was dumped on Quezon City on Saturday, August 30, resulting in flooding.

Citing data from the state weather bureau PAGASA, Project NOAH Executive Director Mahar Lagmay said the accumulated rainfall was 141 mm, with most of it falling between 2 p.m. and 3 p.m., Saturday.

“That's a lot of rain delivered in a very short span of time,” Lagmay said in a Facebook post on Saturday.

He also said the rainfall was even more intense than torrential rain, which usually ranges from 30 mm per hour (mm/hr) to 60 mm/hr.

Despite the absence of a tropical depression, the Quezon City government reported flooding in districts 1, 3 and 4, affecting 36 out of 142 barangays.

According to the local government unit (LGU), rainfall reached 121 mm in just one hour.

This amount exceeded the peak one-hour rainfall recorded during Typhoon Ondoy, which was approximately 90 mm/hr, according to the Quezon City LGU.

“Hindi kinaya ng drainage system ng lungsod ang napakaraming tubig-ulan sa napakaikling oras kaya nagresulta ito ng malalang pagbaha, maging sa ilang lugar na hindi karaniwang binabaha,” the Quezon City LGU said in a statement. 

(The city's drainage system couldn't handle the immense amount of rainwater in such a short period, which resulted in severe flooding, even in some areas not typically prone to it.)