Part 1 

IN THE FIELD of a very hi-tech subject called Fluvial Geo Morphology or FGM (the land mass that a river affects, influence and form), the P4.2-billion Japanese method of solving the Iloilo flood problem is termed as the Hard or Steel and Concrete approach which is the traditional engineering way of solving the flood problem of a city.

This blitzkrieg approach is characterized by widening, straightening, re-channelization and finally concreting of rivers to solve flooding. This is reminiscent of the “shock and awe” U.S. invasion of Iraq where thousands of tanks and armored vehicles supported by hundreds of fighter planes swept through the desert to invade Iraq or the carpet bombing of Tora Bora mountains where mountain-penetrating 5-tonner bombs that were dropped exceed the total bombs used in the entire 10-year Vietnam war. Eventually both operations failed to achieve its objective which is peace in Iraq and neutralizing Bin Laden and his terrorist group.

There is a German word which would aptly describe the Iloilo Flood Control Project: “ SCHLIMMBESSERUNG”, which means IMPROVEMENTS THAT MAKES THINGS WORSE!

This writer will justify its doubts and reservations on the long term effectiveness of the Flood Control Project in a series of write ups and would do its utmost to present it in layman’s term for the easy understanding of The Daily Guardian readers.

The technical reason and basis of all flooding is the very complex subject of FGM- fluvial geo-morphology, which this writer was exposed to the No. 1 expert in the US, Dave Rosgen of Wildland Hydrology, Pagosa Springs, Colorado. (Editor: The author stayed for three months in Colorado Springs, Colorado).

Dave Rosgen uses the Soft Approach in river restoration, control and maintenance which is NOT dependent on iron and concrete but rather on the use of native materials such as stones, boulders and fallen trees applied in ways that enhance the natural tendencies for rivers to seek quasi-equilibrium, both sediment and water, both at low flow and in flood. This will be discussed on the next episode.

The Japanese Hard Approach will temporarily prevent flooding of Iloilo City and part of Pavia where the concrete structures begin for maybe 20 years after project completion but after that, severe flooding will be experienced beyond the concrete structure which will start in Pavia going to San Miguel, Sta. Barbara and Cabatuan areas with magnitude of the recent June 20 devastating flood and at a more frequent interval! Why is this so?

The Tigum/Aganan rivers and watersheds are the SIAMESE TWINS of flooding in our area, hence if BOTH are sick, healing only one twin will NOT solve the flood problem but will only aggravate the condition of both. To properly repair or restore the rivers in Metro Iloilo, one must FIRST OR AT LEAST CONCURRENTLY repair also the watershed which most often is the source of the flood problem. Changes in the watershed that affects the quantity or timing of river flow are: A). trees or vegetation removal; B) Soil compaction because of human activities; C) Urban development; and D) Changes in the structure, size, amounts and source area of sediment.

A river is like a human being that reacts to the load (water and sediment) given by the watershed to deliver from the mountains towards the sea. Within reasonable limits, it can adjust its width, depth and meander if there is an increase in its load that the watershed makes it to transport. Technically this is a river at grade or at equilibrium. Beyond its equilibrium capacity, the river will fight back by destroying its banks and overflow to the plains. If its end portion is concretized as in the Jica Flood Control Project in Iloilo City, then it will vent its ire UPSTREAM in Pavia, San Miguel, Sta. Barbara and Cabatuan. There are many cases of this around the world serialized in the Discovery Channel TV program. In the show, concrete embankments were demolished and returned to natural soil and the straightened portion was also removed to return it to its original meander.

Edmund Burke, a famous author, has this to say: “The use of force alone is temporary. It may subdue nature for a moment but does not remove the necessity of subduing it again, which will make nature perpetually to be conquered.” (To be continued)

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