Tue, Oct 20, 2020 page8

• Lack of typhoons poses problems

  • By Chang Yen-ming 張炎銘
  • • 
    • 
    • 

  Some people are saying the weather has been wonderful this year. That depends on how one defines wonderful weather.

  The Ministry of Economic Affairs last week announced that the alert level for Taoyuan, Hsinchu, Miaoli and Taichung areas are to be raised from green to yellow, and that water pressure is to be reduced at night.

  Few households with water tower storage facilities would have noticed any restrictions on their supply, but people concerned with the water situation have been aware for some time that the lack of typhoons this year, coupled with low rainfall, has meant that in the June-to-September period, reservoir capacity reached on average of only 20 to 60 percent.

  Typhoons bring destruction, but they also bring one significant benefit, and that is torrential rains. Rainfall is inconsistent throughout the year in Taiwan, and the nation relies heavily on reservoirs, which supply the majority of water for households and industry, as well as 30 percent of water for irrigation.

  During the rainy season, if there are no typhoons or rainfall and plum rain seasons fall short of expectations, there is a high likelihood of a drought.

  Northern Taiwan was particularly badly affected during the nationwide drought of 2002, but within two days of a sea warning being announced, Tropical Storm Rammasun dumped enough rain on northern and northeastern Taiwan to raise the water level at the Shihmen Reservoir (石門水庫) from dangerously low to overflowing and, with the exception of minor losses to the farming, forestry, fisheries and husbandry sectors, there was no serious damage.

  Tropical Storm Namtheun in 2010 brought torrential downpours to northern and northeastern Taiwan, allowing water restrictions to be lifted in the Keelung area.

  Given this, what does “wonderful weather” actually mean?

  Heaven moves in mysterious ways; weather patterns can be unpredictable, and a sense of reverence for nature and humility in its presence are necessary for avoiding the worst excesses of flood and drought.

  This is not to say, of course, that in the past an understanding of the rules of nature have not stood us in good stead in this regard, and indeed hydrological engineers have relied on hydrological analysis to inform their planning, based upon the fact that the world follows the natural order of things.

  The rainfall statistics that people glean enable them to use the figures of the past few decades to predict what can be expected in the future, and it is because of this that they can talk of “once in a decade” or even “once in a century” events.

  However, if the weather stops following established patterns, then all statistical analysis becomes unreliable. Over the past few years people have seen record-breaking flooding occur on a frequent basis, and this year the nation has had the first typhoon-less year on record since 1964. This is a matter of some concern: What if the weather is no longer exhibiting any discernible pattern?

  Typhoons tend to strike from July to September. There have been exceptions before, such as Typhoon Xangsane in 2000, which did not come until November of that year, and 2004’s Typhoon Nanmadol, which did not hit until December, but still, the likelihood of a typhoon coming this year is low, and the possibility of drought high.

  Taiwan’s rivers are steep and short, and even in the event of flooding, with the exception of certain low-lying areas, the floods tend to dissipate in one or two days.

  Droughts are more problematic, because people cannot conjure water from nothing. Especially with the summer season soon behind us, there is little wiggle room in terms of water for industrial and household use, neither can farmers go too long without water for irrigation and growing their crops.

  This year’s drought would be extended for several months, and that is not good.

  Chang Yen-ming is a former director of the Water Resources Agency.

  Translated by Paul Cooper
• Most Popular

  • 1

    First person arrested as Danjiang Bridge opens

  • 2

    TSMC shares stumble on report, but losses minor

  • 3

    Navy needs 12 subs for modern fleet: CSBC head

  • 4

    HIMARS to be deployed to islands

  • 5

    Police identify man who engaged in indecency at park