Why is Metro Manila flooding getting worse?

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July 23, 2025 | 12:00am

MANILA, Philippines — Heavy flooding across Metro Manila following strong monsoon rains was not solely due to the volume of rainfall, but also the result of extensive urban development, blocked waterways and coastal reclamation, according to an expert from the University of the Philippines.

Mahar Lagmay, executive director of the UP Resilience Institute, explained that flooding in the capital is a complex, human-induced issue.

“Metro Manila’s floods are compounded by many factors, including encroachment of concrete surfaces, densification of buildings and residential areas, silting of riverbeds and canals, obstruction of waterways by informal settlers, clogging of floodways by garbage, narrowing of rivers due to development on floodplains, draining and filling in of small rivers forcing more water into fewer channels, forest degradation, and reclamation of coastal land,” Lagmay said.

He also pointed out that the convergence of creeks and streets in low-lying areas contributes to flooding, particularly when waterways overflow or when floodwaters accumulate faster than they can drain.

Lagmay also said that much of the flooding problem is due to how humans have altered the landscape over time. Once roads are blocked by floodwaters, traffic builds up and can effectively paralyze movement across the city.

He further explained that floods in Metro Manila fall into two categories: those that pose danger to people and those that primarily cause traffic disruptions.

Citing a Japan International Cooperation Agency (JICA) study, he said traffic jams due to thunderstorm-related flash floods cost P2.4 billion a day from wasted gasoline and lost economic productivity.

To address these issues, Lagmay recommended infrastructure upgrades such as elevating roads or building well-designed drainage systems that feed directly into nearby creeks to reduce the impact of flash floods.

“(These) proposed solutions to the flood problem of Metro Manila may avoid paralyzing traffic problems due to short-lived rain events,” he said.

As the government grapples with worsening flood conditions, Finance Secretary Ralph Recto disclosed that the Department of Public Works and Highways is seeking P200 to P250 billion from the 2025 national budget for flood mitigation, as part of its total proposed P850 billion allocation.

Speaking on One News’ “Storycon,” Recto emphasized that the administration is prioritizing infrastructure and flood control projects with the highest economic return to support sustainable growth.

“We need to choose the right projects with the highest economic multiplier effect to ensure that the economy grows sustainably at a faster rate of six percent,” he said. — Rainier Allan Ronda, Mark Ernest Villeza, Jose Rodel Clapano