Valenzuela most severely flooded from ‘Ondoy’

In the aftermath of Ondoy, most of the attention was focused on Marikina and Quezon City, which suffered the highest death toll in metropolitan Manila. But the cities of Valenzuela and Muntinlupa were found to have experienced the worst flooding, with 90 per cent of their barangays under water. At least seven cities in the national capital were severely flooded after tropical storm Ondoy dumped record rainfall last Sept. 26, with some areas still under water more than a week later, a list compiled by GMA News Research from local governments in Metro Manila shows. Flood waters reached as high as the roofs of two-storey houses in 127 barangays in Valenzuela, Muntinlupa, Pasig, San Juan, Marikina, Quezon City, and Pasay. In Valenzuela and Muntinlupa, all but one of their barangays were ravaged by floods.

In Quezon City, most of the fatalities came from Barangay Bagong Silangan, one of its most populated barangays. Bagong Silangan lies on the west bank of Marikina River and Calamiong creek, and most of the houses of informal settlers are concentrated along the river bank and creek side. “Catch basin itong lugar dahil mababa. Dumagdag pa yung tubig galing Montalban kapag umapaw sa San Mateo, wala nang dadaluyan yung baha," Barangay Captain Armando Endaya told GMA News. Built-up floodplains Dr. Alfredo Mahar Lagmay of the University of the Philippines’ National Institute of Geological Sciences says a combination of factors contributed to the severe floods that devastated parts of metro Manila. “Malakas talaga yung ulan, tuloy-tuloy in just a short period of time," says Dr. Lagmay. The Philippine Atmospheric Geophysical and Astronomical Services Administration (Pagasa) reported that Ondoy brought 341 millimeters of rainfall from 8 AM to 2 PM, more than the highest recorded rainfall 42 years ago. In 1967, 334 millimeters of rain poured within 24 hours; Ondoy surpassed the record in just six hours. Lagmay says the recent commercial and residential developments along the Marikina River floodplains contributed greatly to the flooding, and to the number of deaths in the area.
View Marikina City in a larger map A map of the Marikina River traversing the Provident and Tumana areas in Marikina, two of the worst hit areas in the metropolis, shows the compression of residential and commercial centers right on the floodplains. “Kung 100 years ago, nangyari yung ganitong ulan, babahain din, pero makikita mo tataba yung tubig sa floodplains. Pero dahil may nakabara na ngayon, di na maka-agos," Lagmay says. Lagmay explains that the natural course of the river would be to swell in the floodplains around it and flow out. However, the built-up areas on the floodplains have prevented the Marikina River from swelling, which would have been its natural behavior, he said. Instead, the water diffused all over the city, causing massive flooding even in areas not usually prone to floods. “Nag-populate ka na ng Metro Manila. Wala nang madaanan yung ilog," says Lagmay. Most densely populated areas Marikina and Quezon City, which suffered less in terms of the number of barangays severely affected by floods compared with other cities, had the worst death toll. Even though less than a quarter of its barangays were severely flooded, Quezon City had 54 deaths as of the last update of the National Disaster Coordinating Council on Oct. 3. Most of them were informal settlers in Barangay Bagong Silangan, which ranks seventh out of 142 barangays in Quezon City in terms of population. Marikina shares Quezon City’s tragic story, with 50 deaths although only half of its barangays suffered from massive floods. Most of the fatalities were found in the hard-hit areas of Provident Village and Barangay Tumana. Outside metropolitan Manila, the province of Rizal had the highest number of fatalities. In Central Luzon, the provinces with the most number of deaths are Bulacan with 35 and Pampanga with 12. The top three severely affected regions – metropolitan Manila, Calabarzon, and Central Luzon - are also the country’s most densely populated areas. The latest data from the National Statistics Office shows that 18,650 people are crammed per square kilometer in Metro Manila. Region IV-A is a far second with a density of 707 persons per square kilometer, while Region III comes third with 451 people per square kilometer. - With reports from Brenda Barrientos, GMA News Research