MMDA, UP to study 39 sites for flood detention basins

The Metropolitan Manila Development Authority (MMDA) and the University of the Philippines (UP) are studying 39 proposed flood detention basins under the government's Oplan Kontra Baha program, with officials assessing potential locations to ensure the facilities can effectively reduce flooding before public funds are spent on construction.

MMDA chairperson Romando Artes said the 39 sites were identified through a feasibility study commissioned by the Department of Environment and Natural Resources (DENR), while the UP Resilience Institute and Nationwide Operational Assessment of Hazards (UP NOAH) Center have separately proposed more than 150 potential sites in Quezon City alone.

“Hindi basta-basta maglalagay ng detention basin sa kung saan-saan. Pinag-aaralan po iyon. Bago tayo mag-invest o gumastos ng isang piso ay alam na natin kung magiging epektibo siya o hindi,” Artes said during a press conference following the signing of a memorandum of understanding between the MMDA and UP.

Detention basins temporarily store excess rainwater and release it gradually to prevent drainage systems, esteros and rivers from being overwhelmed during heavy rainfall.

“Instead na maging run off water, maging baha, temporarily i-catch natin yung tubig, i-delay natin yung papunta sa mga major waterways para po hindi ma-overwhelm yung ating mga drainage, yung atin pong mga esteros, canals, at ilog,” Artes explained.

Meanwhile, UP Resilience Institute executive director Alfredo Mahar Lagmay said historical maps could help identify waterways that had been built over as Metro Manila urbanized, providing additional information for flood-control planning.

He cited the university's proposed detention basins beneath basketball courts in Quezon City and said some sites where facilities had been built were already showing results.

Lagmay also pointed to open spaces that could serve as temporary water-storage areas, helping reduce flooding in downstream communities, including Caloocan, Valenzuela, Malabon, Navotas, San Juan and Manila.

UP president Angelo Jimenez said the agreement would establish a framework for research, technical assistance, knowledge-sharing and capacity-building to support flood mitigation.

“Detention basins can help manage excess storm water by temporarily storing during heavy rainfall and releasing it gradually, easing pressure on drainage systems and waterbodies,” Jimenez said.

“But we must also recognize that no single intervention can eliminate flooding risks,” he added.

Severe monsoon rains and tropical cyclones in August affected about 9.6 million people across Metro Manila, Calabarzon and the Visayas, resulting in 44 deaths and more than P8 billion in infrastructure damage, Jimenez said. A leptospirosis outbreak was also reported in September.