Sun, May 05, 2002 - Page 2 News List

Coming to terms with drought

WHAT'S BEING DONE While water-resources agencies deal with the shortages, officials are considering longer-term measures to prevent this from happening again

By Chiu Yu-Tzu  /  STAFF REPORTER

A man walks on the dry bed of the Shihmen Reservoir in Taoyuan County. The water level at the reservoir has almost fallen to the ``dead storage'' level, below which water has to be pumped out to serve consumers.

PHOTO: GEORGE TSORNG, TAIPEI TIMES

With water-conservation measures starting to bite around the country, the question the public most wants answered is: "When will the drought end?"

"It's very hard to say," Chen Shen-hsien (陳伸賢), spokesman and deputy director of the Water Resources Agency (水利署), told the Taipei Times.

"The drought emergency might be lifted if the heavens give us three days of torrential rain concentrated in watersheds."

At the Shihmen Dam (石門水庫) in Taoyuan County, one of the major reservoirs in northern Taiwan, water levels are falling close to the "dead storage" level, below which water has to be pumped out to supply to consumers.

Agency officials expect the reservoir to reach its dead storage level next month if no rains come. The dam has never reached its dead storage level since it was opened in 1964.

"We will be safe if the water levels remain above the dead storage level at the major reservoirs by the middle of June, when the dry season ends," Chen said.

But for this to happen, the country needs rain, and a lot more than it has been getting so far this year.

The average rainfall from January to April this year was only 30 percent of the average for this period. The Central Weather Bureau has forecast that rain will not come until the middle of this month.

Not like other natural disasters

Unlike other natural disasters, such as floods or earthquakes, drought creeps across the nation slowly, gradually affecting people's daily lives.

When a drought emergency is announced, officials said, all that people can do is consume the available water as slowly as they can.

"That's why we need to save water during the rainy season to cope with times of drought," Tyan Chau-ling (田巧玲), a senior engineer at the agency's Water Resources Division, told the Taipei Times.

"This is Taiwan's chief operating principle in water-resources management."

In the south, 90 percent of the total rainfall comes during the wet season, from May to October. In northern Taiwan, 60 percent falls during this season.

Taiwan's topography, however, makes it difficult for water-resource agencies to collect water during the wet season. Rivers originating in the Central Mountain Range are short and steep, causing runoff to flow rapidly out to the sea.

According to the agency, based on data collected between 1989 and 1998, Taiwan receives an average of 89.15 billion tonnes of rainwater a year.

However, only a small percentage of this can be retained.

A little over 24 percent of the rainfall evaporates before it can be collected. Of the water that remains on or in the ground, 4.257 billion tonnes are collected at reservoirs, 7.503 billion tonnes are diverted from rivers and 6.281 billion tonnes are pumped from under the ground.

"Accumulating as much water as we can is absolutely essential for Taiwan," Tyan said.

Taiwan already has about 40 reservoirs. But officials still argue that Taiwan has no choice but to build more reservoirs to trap rainwater.

The opportunities for developing new supplies in Taiwan, however, are becoming fewer.

The cost of a new reservoir is increasing because the number of appropriate sites is decreasing, officials said. Moreover, environmental awareness has become a more important factor in building reservoirs.

New tactics

"Building large reservoirs will not be as easy as before. So we have to adopt new ways to develop water resources, such as desalinating seawater and building artificial lakes" Chen said.

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