Waterways and drainage systems clogged with debris and garbage are to blame for flooding in Metro Manila, and not reclamation, an environmental impact expert said over the weekend.

Dr. Ed Alabastro explained that the problem of flooding in the metropolis has been going on for a long time, way before the start of reclamation projects at Manila Bay.

"The root cause of this problem is our clogged drainages and waterways. Water cannot flow freely through these channels because they are obstructed by garbage and other plastic materials," said Alabastro, chairperson of the Air and Waste Management Association.

He also debunked other assertions by critics of the reclamation projects that they cause land subsidence, tsunamis, and a rise in the sea level.

"Land subsidence is not due to reclamation at sea but to the over-extraction of deep well water," Alabastro said, referring to the gradual or sudden sinking of the ground due to displacement of subsurface earth materials.

Rising sea levels

A two-year study commissioned by the National Economic and Development Authority has warned that by 2040, around 12 million people are likely to be exposed to flooding in the National Capital Region due to rising sea levels and subsidence.

The study conducted by foreign and local experts laid down a Manila Bay Sustainable Development Master Plan to stem the ill effects of flooding.

"At present, minimizing dependency on groundwater is a challenge, resulting in a decrease in sources of safe, clean water and continuous and faster land sinking," it said.

It pushed for the reduction of groundwater extraction as it urged local government units and the Department of Public Works and Highways to look for alternative sources of water.

Alabastro also stemmed concerns about tsunamis arising from rising sea levels, saying their occurrence has nothing to do with reclamation.