Much of the trouble comes from rapid development without planning laws being properly enforced. Areas which were once farmland or forest are now covered in comcrete or in many parts of Manila in corrugated steel roofing; the water has nowhere to go.

People used to avoid building near hillsides because of the risk of landslips - now they feel they have to take the risk.




When you have a mountain range to the west of Manila chucking extraordinary amounts of water from hills in Antipolo and dumped into the Pasig river almost at once, every small river and water reservoir will(has) burst.
At the end of the day you have to put all that water somewhere else..and quick.

One solution that I think might work is explained here..

http://z6.invisionfree.com/flipzi/ar/t1.htm