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A flood of problems: 8 steps cities should take

By PAULO ALCAZAREN, The Philippine STAR Published Nov 13, 2020 10:29 pm

Typhoon Ulysses has just left us. It was déjà vu for many who survived Ondoy a decade ago. Although rural areas were as hard hit as urban settings, six out of 10 Filipinos live in towns or cities.

Philippine cities and towns need to address the problem of flooding and here are eight steps that should be taken:

1. Clean and maintain city drains, canals and rivers year round.

Maintenance is not usually found in our government’s vocabulary and this needs to change. The best time to do this maintenance is, of course, before the rain comes, and do it every year.

2. Require rainwater harvesting for all home and buildings.

Collecting storm water falling on roofs and on building sites in cisterns will help the city’s overtaxed drains cope with the volume. The water harvested can be used for irrigation or flushing and cleaning afterwards.

Cities should build more parks to absorb rainwater and provide relief.
3. Build more parks.

Open green space absorbs rainwater and parks are needed in any case for relief and as refuge areas in times of disasters. Cities should aim to provide a park within 10-15 minutes of where everyone lives.

4. Plant more street trees.

Tree canopies and root systems absorb rainwater and many more trees can be planted along streets than in limited areas of parks.

Cities must plant trees everywhere, as Singapore has done, since trees sop up storm water.
5. Build rain gardens alongside streets and empty lots.

Instead of shrub planting, a rain garden is constructed like a swale or depressed detention basin that absorbs more water than just a bed of plants or grass.

6. Require perforated paving in car parking areas.

Solid concrete in our car parks channel storm water directly to overburdened drain system. Perforated paving blocks or pervious concrete is available in the Philippines today.

Cities have to encourage the building of green roof gardens to feed on rain water.
7. Give incentives to owners and developers for green roofs and vertical green walls.

These provide additional areas to absorb rainwater. Every little bit helps.

8. Coordinate with surrounding cities and towns for all these interventions.

Floodwaters do not stop at political boundaries and any program for flood control and mitigation can only work in a larger physical context each city or town finds itself in.

The reasons for flooding go beyond the political or even the physical boundaries of Philippine towns and cities. Floodwaters come from upland areas and mountain ranges (like the Sierra Madres for Metro Manila) that have lost their forest cover from over logging, or because of indiscriminate quarrying. The water then flows quickly down to the lowlands.

Flooding happens also when agricultural land around major towns and cities are converted to residential subdivisions or commercial development. They replace the open green space that absorbs rainwater before they get to urban areas.

Cities can encourage green walls also to help  channel rain water from drains.

The loss of agricultural land also means that we need to source our food from farther and farther away, making our cities’ carbon footprint huge and expansion unsustainable.

Flooding happens when there is little urban planning. Cities and towns then succumb to the temptation of unfettered real-estate development. Land use is not controlled, much less anticipated, so that public infrastructure like drainage becomes inadequate to address outcomes of opportunistic development.

Flooding happens ultimately when we do not acknowledge the science and the data that shows we are paying the price for haphazard urban development in our low lands and the lack of resource management in our uplands. Geo-hazard maps and aerial imagery abound and one can see the evidence of our wanton neglect on any computer with Google Earth (click historical imagery).

Cities must incorporate rain gardens to act as sponges for storm water like this in Boracay.

Flooding happens when we do not plan for urban development. What is needed is the participation of a well-informed public and the aid of government agencies cooperating with each other at all levels, as well as the technical expertise of environmental planners, landscape architects, and green building architects.

Governance in our metropolitan areas like Metro Manila is fractured and it is hard to get 17 local government units to cooperate.

Finally, flooding happens when we forget the problems we face regularly after the sun comes out. We then forget to take action to address the problems we definitely will face again next year.

Some of the solutions, like better maintenance of infrastructure, can be done immediately. But many interventions, like reforestation, will take years to a decade to become effective.

We have no choice. If we do not acknowledge the realities we face and take action now our future will be flooded with disaster.

Feedback is welcome Please email the writer at [email protected].


Banner photo by Edd Gumban/Philippine Star