How do we solve our flooding problem?
With the recent floods in the Philippines brought about by Tropical Storm “Gorio,” we are once again reminded of a problem that comes to us with great regularity and increasing severity.
“Bakit bumabaha sa Manila?” Why does it flood in Manila? As a civil engineer teaching at the University of the Philippines Los Baños, I always asked my students that question.
Some blamed the drainage system which they described as poorly designed; others blamed the garbage that clogged sewer lines. Some cited the city’s concrete as lacking the porosity that allows floodwaters to recede faster.
Of course, I appreciated those answers because, indeed, inadequate drainage systems and high imperviousness aggravate the problem of flooding. But if these were fixed, would Manila be flood-free?
The answer lies not in Manila’s drainage system or land cover, but in its geography: Most parts of Manila are situated in a floodplain — the area adjacent to a river that is inundated when water rises.
A floodplain is fertile land suitable for agriculture, but when people transform it into a residential or commercial area, it becomes flood-prone. Therefore, from an engineering perspective, Metro Manila will always be vulnerable to flooding: The drainage system, no matter how well-maintained, can only store water from precipitation itself but not when the river swells. The same may be said of other areas in the country situated near creeks and rivers.
This conundrum begs the question: If floods are inevitable, what can we do about them?
First, we need a reliable flood forecasting system. Fortunately, our scientists have initiated efforts toward this direction, including Mahar Lagmay and his colleagues in Project NOAH, as well as Enrico Paringit et al. of UP Diliman’s DREAM program. But more work needs to be done: There are still many areas in the Philippines without flood maps. In the United States, approximate but expedient terrain-based flood mapping that does not need ground surveys has been gaining popularity. The application of such a method in the Philippines must be explored.
In my studies at the University of Texas at Austin, I have been privileged to witness the United States’ move toward a contiguous National Water Model, which increases forecast locations from 4,000 to 2.7 million.
In the Philippines, the UPLB project of formulating a national water security roadmap — in conjunction with the National Water Resources Board—is a welcome development. But such plans must go beyond what Ernesto Ordoñez, secretary general of the National Water Roadmap Summit, called “ningas kugon” in a presummit meeting held on July 12, which I attended. As with Project NOAH, such initiatives can only stay afloat with enough government support.
Second, there must be interoperability between forecasters and local government units: Forecasts must reach local emergency responders. Our flood warning and response system must be strengthened. Again, there have been advancements toward this end. For instance, an SMS warning system is now in place in vulnerable areas. Also, Project NOAH’s inclusion in the Pre-Disaster Risk Assessment system of the National Disaster Risk Reduction and Management Council has undoubtedly saved thousands through timely warnings of incoming floods. We should support these and similar efforts.
Finally, data sources must be readily available to the public. The fact is that there is no openness of data in our country. While many reasons can be offered for such secretiveness, like security, I find it ironic that when I made Philippine flood maps, I had to rely on US agencies to download Philippine data. Moreover, many researchers around the world—students, for example—would like to study the Philippines’ flooding situation but are impeded because of lack of data. International collaboration will surely accelerate the knowledge and skills required for this.
The Philippines, while blessed with water resources, will continue to be vulnerable to floods. But there are ingenious ways that we can adopt to address this problem. Floods are here to stay, but we need not suffer their consequences.
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Jonathan David Lasco is a PhD researcher majoring in environmental and water resources engineering at the University of Texas at Austin.
