Why did many QC areas get flooded? Rainfall for 1 hour exceeded Ondoy's, LGU says

Many areas in Quezon City got flooded on Saturday, August 30, after heavy rains poured.

Floodwaters on Mother Ignacia Avenue rose to around average human height in less than an hour, according to a report by Darlene Cay on 24 Oras Weekend.

Other areas that got flooded were Katipunan Avenue in Loyola Heights, EDSA-North Avenue, Maginhawa Street, EDSA-Seminary Road, Araneta Avenue, Mindanao Avenue, Elliptical Circle, Commonwealth Avenue, and P. Florentino Street, among others.

Traffic was at a standstill in many areas due to the floods, and commuters had difficulty going home.

"Matinding pagbaha ang naranasan sa ilang lugar sa Quezon City kaninang hapon lalo na sa District 1, 3 at 4, na nagdulot ng perwisyo at pagkaabala sa publiko," the Quezon City local government unit said in a statement on Saturday.

(Intense floods were experienced in some areas in Quezon City this afternoon especially in Districts 1, 3, and 4, which resulted in inconvenience to the public.)

It said 36 out of 142 barangays were affected by flooding.

The QC LGU said the amount of rainfall on Saturday was "phenomenal", exceeding the hourly amount that fell during Tropical Storm Ondoy in 2009.

"Sa preliminary analysis ng UP Resilience Institute at UP NOAH Center batay sa rain gauges at weather stations sa Metro Manila ng PAGASA at IRISEUP ng QC government, mailalarawan bilang 'phenomenal' o pambihira ang pag-ulan kanina na ang pinakabulto ay naitala sa Quezon City at Nangka, Marikina," the LGU said.

(In the preliminary analysis of the UP Resilience Institute and UP Noah Center, based on the rain gauges and weather stations in Metro Manila of PAGASA and IRISEUP of the QC government, the rainfall can be described as 'phenomenal' or extraordinary. The bulk of the rainfall was recorded in Quezon City and Nangka, Marikina.)

"Umabot sa 121 millimeters sa loob lamang ng isang oras ang kasagsagan ng ulan kanina sa Quezon City, higit na mataas kaysa sa pinakamataas na lakas ng ulan sa loob ng isang oras noong panahon ng Bagyong Ondoy (~90 mm/oras)," it added.

(The amount of rainfall reached 121 millimeters in just one hour in Quezon City, which is much more than the highest amount of rainfall in an hour during Tropical Storm Ondoy, which was 90 mm/hour.)

"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 statement read.

(The drainage system of the city was not able to deal with the big volume of rain water in such a short time, which resulted in intense flooding even in areas that usually do not get flooded.)

"'Phenomenal' talaga ang rainfall yesterday. In 24 hours, mataas talaga 'yung rainfall in a short span of time," Quezon City Disaster Risk Reduction and Management Office spokesperson Peachy de Leon said in an interview on Super Radyo dzBB on Sunday.

(The rainfall yesterday was really 'phenomenal'. In 24 hours, there was a high amount of rainfall in a short span of time.)

"Kakaiba lang talaga ang bagsak ng ulan kahapon. Ang peak intensity sa QC ay 121 millimeters. Eh 141 millimeters ang naitala kahapon [in 24 hours] sa weather station. Kakaiba talaga. Malakas po talaga yung bagsak ng ulan," she said.

(The rainfall yesterday was extraordinary. The peak intensity in QC was 121 millimeters. A total of 141 millimeters was recorded in the weather station. It was really extraordinary and torrential.)

De Leon said due to the heavy rainfall, alert level 3 was raised in San Juan River.

"Sa waterways, 'yung nag-alert level 3 si San Juan River. So 'yung mga dinaanan nitong rivers, 'yun ang talaga tumaas," she said.

(In the waterways, San Juan River reached alert level 3. So the rivers connected to it had their water levels up.)

Some residents in affected areas were rescued and evacuated.

"As of 11:15 p.m. kagabi, mayroon pang evacuees. Pinag-stay muna sila [sa evacuation centers] until today," de Leon said.

(As of 11:15 p.m. last night, there were still evacuees. They were told to stay at evacuation centers until today.)

According to De Leon, the floods have already subsided.

"Naging mabilis naman ang paghupa ng tubig dahil sa walang humpay na declogging operation ng Department of Engineering na isinasagawa buong taon. Agad na ring kumilos ang Department of Sanitation and Cleanup Works para maalis ang mga gamit ng mga residente na tinangay ng baha at humarang sa mga daluyan ng tubig," the LGU said.

(The floods subsided quickly due to the continuous declogging operation of the Department of Engineering done year-round. The Department of Sanitation and Cleanup Works immediately acted to remove residents' belongings that were carried away by floodwaters and obstructed waterways.)

Meanwhile, assets and personnel have already been placed on standy and are prepositioned in anticipation of possible heavy rainfall again.

"Ngayon ang weather update ay uulan pa rin po (It will still rain today)," De Leon said.

PAGASA said Metro Manila, MIMAROPA, Zamboanga Peninsula, Northern Mindanao, Caraga, the rest of Visayas, and the rest of CALABARZON may expect cloudy skies with scattered rains and thunderstorms on Sunday due too the Southwest Monsoon (Habagat). Moderate to heavy rains may possibly result in flash floods or landslides. —KG, GMA Integrated News