Sun, Sep 02, 2018 - Page 6 News List

Questions about floods might miss key factors

By Jay Lee 李文正

After the torrential rain that fell in southern Taiwan last month, a wave of simplistic criticism has emerged, asking questions such as: “How have all those dozens of billions of New Taiwan dollars of flood-prevention funding been spent in Tainan and Kaohsiung?” and: “Why is flooding still happening?”

However, there is no discussion about technical details. It seems as if anyone who gives an explanation is offering bureaucratic excuses on behalf of the government.

Is that true?

The precipitation in Tainan and Kaohsiung, as well as Pingtung County, on Aug. 23 was indeed astonishing. Rainfall in much of the three areas far exceeded the “extremely torrential rain” level — accumulated rainfall of 500mm or more over a 24-hour period, according to the Central Weather Bureau — so that in just a single day, the totals topped more than the annual rainfall of many places across the globe.

ASTOUNDING RAINFALL

This is by no means ordinary “heavy rain,” which might be difficult to comprehend for people living in Taipei, who spend their typhoon holidays in department stores, KTVs and cinema complexes.

With regard to Tainan’s flood-prevention engineering, the city was allotted the largest share of all cities and counties, 20 percent — NT$16 billion (US$520.6 million) — of the central government’s NT$80 billion, eight-year flood-fighting budget, which has come under heavy criticism following the deluge, as people are wondering how there can still be so much flooding with all that money being spent.

In addition to such sentiment, the public should bear in mind that flood-prevention engineering always includes determining the project’s flood-prevention capacity, which, simply put, decides — based on the budget — how much rainfall the project should be able to handle when construction is complete and the project passes the final inspection.

The NT$16 billion in Tainan should have achieved a flood-prevention capacity of 250mm of rain, but the rainfall on Aug. 23 went far beyond that level, in many places reaching twice that volume on that one day alone. Expecting there to be no flooding under these conditions is fundamentally no different from asking for a miracle.

PREVENTION CAPACITY

Taking that into account, people might ask why flood prevention capacity standards were not raised at the time of construction, given that the capacity was not enough. Those who do might think that raising the capacity to 500mm of rain — or even 700mm — would be enough, but they might not be aware of the budget limitations and the difficulty involved in the engineering work.

Many people have the impression that flooding tends to occur less frequently in northern Taiwan, but there are several factors accounting for that difference.

First, the geography renders prolonged and extremely heavy rainfall less likely in northern Taiwan.

Second, the regional flood-control budgets differ: The budgets for the Tamsui (淡水河) and Keelung (基隆河) river basins were more than NT$30 billion and NT$50 billion respectively, far exceeding the amounts allotted to a whole city or county in southern Taiwan.

No one wants flooding to happen, but given this situation, one cannot help but wonder whether it is fair to criticize the budgets allocated to the southern parts of Taiwan as being a waste of money.

Jay Lee is an adjunct teacher of citizenship at National Nanke International Experimental High School.

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