Floods and urban planning

Floods and urban planning image

Text: Tito F. Hermoso / Photos: Russell Co | posted August 22, 2012 10:24

A vicous cycle unless a proper measure is put into place

Let if flow

Like traffic, floods are a flow problem. Where there is a source leading to a drain, there should always be an allowance for passage and a blow-off valve for the excess when it surges. In the Metro's case, rain in excess of what falls on populated areas come upstream from the mountain water sheds of the Sierra Madre. All that water flows down through the Metro's rivers to drain in Manila Bay and Laguna de Bay.

Nowhere to go

The Metro's proximity to both is both a bane and benefit. While the excess or surge rain water doesn't have to travel that far to drain into the lake and the bay, both the lake and the bay are also under the same canopy of rain that pours over the mountains. So you end up with a topography that is prone to saturation. i.e. all that rain everywhere with nowhere to go.

Cut and paste

Sure, there's the annual dredging and canal clearing but that only keeps the water passages clear for the first few hours of red alert rain, defined by PAGASA as rainfall over 30mm/hour. Every year, the list of flood and landslide hit areas read like a cut-and-paste list from previous years; Tatalon, Roxas district, Tunasan, Tullahan, Sampaloc, Litex, Pasig, Pateros, Pasay, Maricaban, Kalentong, Maysilo, Antipolo, Cainta, Marikina, Bacoor, Paranaque, CaMaNaVa, Laguna, Taguig, Taytay, Muntinglupa, etc.

Central Luzon too?

Central Luzon, like Metropolitan Manila, is likewise victimized by seasonal flooding, but with different consequences. The refertilization of the soil by alluvial flood is Nature's way for keeping Central Luzon the country's rice granary through many centuries. The problems in Central Luzon lie in the urbanized settlements that were built where, unfortunately, floods occur. On the other hand, floods in the Metropolis only provide fertile ground for cursing.

Saving for a rainy day

Since 1978, the government has been trying to pursue programs to expand the water impounding capacities upstream in the mountains and accelerate drainage downstream to the lake and bay while ensuring that the conduits in between do not impede flow. All that water need not go to waste as government is also trying to impound as much as it can for droughts and the growing demand for 365 days/year potable water.

Civic minded opposition

The programs are very simple in concept. Building additional Umiray-like trans-basin tunnels, man-made rivers and several catchment dams upstream in the Sierra Madres and impounding dams along the way from watersheds to Angat Dam, La Mesa Dam, Wawa dam and the proposed Laiban Dam are on the drawing boards. Downstream, continuous dredging of the Metro Manila river system are in process though, sadly, the long overdue dredging of Laguna de Bay has consistently been opposed by some civic minded groups.

NLEx Bulacan waterworld

Opposition to building the extension of the CaMaNaVa dike to the coastal Bulacan towns of Obando and Paombong have induced the aggravated tidal sinking of western sections of Meycauayan, Marilao, Malolos, Calumpit and Bocaue in Bulacan. Nowadays, every time the Bulacan dams open, large swathes of the province goes under water rendering the NLEx Balintawak to Bocaue section, the main entry point of food and goods to Manila, impassable.

Sky high costs or waist deep flood?

There are no lack of PPP proposers and ODA funders for both upstream and downstream flood and water shortage solutions. The downer is cost. To make the Laiban Dam project feasible, the proponent had to set a high purchase price for water utility distributors forced to buy the impounded water. To make dredging of Laguna de Bay feasible, pie-in-the sky lakeshore real estate projects had to be conjured.


The high cost largely goes to relocating settlers, formal and informal, away from the path of the water channels. Concerns dealing with their livelihood and uprooted domestic lives are legitimate. Some 1M to 2M families living on the pathways, wittingly and unwittingly, impede the drastic measures needed to mitigate the annual pluvial disasters that befall some 15M to 20M Metro and Calabarzon inhabitants.

Pinatubo wishes?

No one in his right mind would wish for a Pinatubo like catastrophe that forces a massive evacuation which alters the cadastral character of a huge swathe of topography just to clear the urbanization of the ex-swamps of the Metropolis and lake shores. Whether urban dweller, farming or fishing town resident, its probably only human nature to bear with floods several weeks of the year for so long as the source of livelihood is proximate to the home.

Time will tell

Nevertheless, relocation drives the project costs upward. JICA, one of the original financiers of the Laiban Dam project, realistically projected not only these relocation costs but also the ten years needed to clear the areas out for full blast construction. Obviously, these projects will take time to implement, so Metro folk will have to steel themselves for several more years of annual flooding before the positive effects of these projects are felt.

The colonizers knew better

Perhaps the Spaniards knew something we don't. If the their urban planners of 400 years ago were alive today, they would be aghast at the cities we built in the very delta marshes and swamp land where they loathed establishing even temporary cantonments. Manila, after all, was their 3rd choice for a capital, after Cebu and Legazpi City. They rued the day they built Malacanang in the humid marshes by the Pasig. Cooped up in Intramuros, they didn't mind if Quiapo and Tondo sank as it was mostly populated by 'Chino' traders. The Spaniards preferred the higher ground of San Juan and Makati. The New England Brahmins of the ensuing American colonists did one better. They built a summer capital in the highlands of Baguio. Oh, it also floods there nowadays? Credit the amazing powers of poor urban planning.

The 'ber' balm

As we usher in the 'ber' months and the world's longest Christmas season begins, thoughts on how to mitigate against floods and torrential rain take a back seat in our Cerebral Cortex as many aim to get the most out of December 25. Traffic or high water persisting, it would appear that anticipating Christmas is a needed psychic balm, to better deal with, well, what do you know, the floods and the traffic that persist year in year out.