THE PHILIPPINES needs to invest in infrastructure that incorporates nature-based solutions to flooding, according to the Organisation for Economic Co-operation and Development (OECD).

In a working paper, “Nature-based solutions for flood-management in Asia and the Pacific,” the OECD said that existing studies on flood management in the Philippines lack both scientific basis and government-supported.

“A lack of guidelines, rules and evidence hampers nature-based solutions implementation,” the OECD said. “Challenges to adopting nature-based solutions can also come from institutional and legislative barriers.”

Nature-based solutions for flood control vary depending on location, the OECD said, noting how river basins and coastal areas have their own risk profiles.

It cited the need to address clogged waterways caused by solid waste, dikes and bridges. Instead, the Philippines must revive old river channels, add vegetation along riverbanks, and construct bypass channels for water passage.

Flood management infrastructure in urban areas also remains outdated and cannot handle average levels of rainfall, the OECD said.

“Areas surrounding the city’s waterways are often characterized by high population density, with dwellings encroaching over the water and disrupting water flow, and a significant share of informal settlers residing in inadequate housing near waterways, making them especially exposed to flooding,” it said.

The OECD noted that government budgets for flood protection increased between 2008 to 2016, a possible reaction to widespread flooding resulting from Typhoon Ketsana (Philippine name: Ondoy) in 2009.

However, it noted that results of the investment are unclear “as there has been no noticeable decrease in the death toll and economic damage from floods.”

Asia-Pacific countries were urged to invest in ecosystem restoration and conservation to reduce flood risk. The OECD called for the “balanced” use of “green” and “grey” infrastructure based on the flood risk profile of each area to help manage water-related disasters.

The Philippine economy may incur losses worth $124 billion between 2022 and 2050 due to heavy floods, storms and prolonged droughts, research firm GHD has said.

Floods in the region account for 41% of the 5,216 recorded disasters between 1980 and 2022, occurring the most in the Philippines, China, Indonesia, and India, the OECD said. — Beatriz Marie D. Cruz