Tue, Dec 08, 2009 - Page 4 News List

FEATURE : National rainfall patterns set to change

By Vincent Y. chao  /  STAFF REPORTER

Long-term projections have shown that rainfall is likely to decrease in the nation’s southern, central and northern areas and increase in eastern areas, researchers have said.

Liu Chung-ming (柳中明), a professor at National Taiwan University, said these developments were a result of shifting north eastern prevailing winds rather than climate change. However, climate change is likely to exacerbate the situation, creating more anomalies in rainfall patterns and possibly leading to longer droughts, he said.

“Taiwan’s eastern counties are likely to experience an increase in water supply compared with water use, while water supply may become more precarious in other regions, especially the central area,” Liu said.

He said these areas may experience shorter and more concentrated rainfall patterns that will do little to replenish water reserves in the nation’s reservoirs.

“In Tainan County, for example, the previous average for days without rain was 204. In the first 10 months of this year alone, there have been 252 days without rain — the figure is likely to be closer to 300 by the end of December,” Liu said.

In response, officials from Taiwan Water Corp said the company would monitor the situation and acknowledged that shifting weather patterns and climate change could result in longer droughts and more concentrated rainfall.

It would take a two-fold approach to address these changes, first by lowering water use through education and promotion, and then by limiting usage if necessary, the officials said.

Methods used to deal with water shortages range from reducing water pressure at night, placing restrictions on large water users like swimming pools and car washes, and, if necessary, alternating water rationing and stoppages between different areas, the officials said.

An official, who spoke on condition of anonymity because he was not authorized to comment on the matter, said water levels this year have been precarious and the corporation may start limiting water use in central and southern regions starting from the Lunar New Year, depending on levels of water reserves.

Water levels in reservoirs in the Miaoli area in central Taiwan, which are responsible for supplying Tainan and Kaohsiung, are at 50 percent of capacity compared to 84 percent in Shihmen Reservoir in northern Taiwan, the official said. As a result, it is likely there will be water shortages in the areas before the end of the dry season in May.

Officials at the Water Resources Agency (WRA) acknowledged that water shortages may increasingly become a problem in the future, and said that it was working on a series of initiatives to tackle the situation.

“Our data indicates that droughts may become more frequent in future years compared to 60 years ago. Rainfall disparity has risen to 1,500mm annually, from 1,000mm previously,” said WRA spokesman Wu Yueh-si (吳約西), who is also the agency’s deputy director-general, adding that floods and mudslides may become more common.

In recent years, the agency has been busy upgrading reservoirs to deal with increased silt from heavier rainfall and extreme weather such as Typhoon Morakot, Wu said, adding that the agency is also planning to create backup water sources while creating more sustainable water initiatives for towns and villages modeled on similar initiatives found in Japan.

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