Water crisis drives new research into reservoir turbidity


Sat, Sep 11, 2004 - Page 2

With officials expressing relief that a two-week interruption of the water supply had ended, the Ministry of Economic Affairs yesterday demanded the creation of an alarm system that would point to fluctuations in the turbidity of water destined for human consumption.

Turbidity is a measurement of drinking-water quality. The recent water crisis in Taoyuan has been attributed to the abnormally high turbidity of untreated water in Shihmen Reservoir.

According to Joses Wu (吳約西), the secretary-general of the Water Resources Agency, the pioneering research might take a long time.

"We will firstly suggest establishing a monitoring system for water quality in the upper reaches of the reservoir," Wu told the Taipei Times.

The agency said that between Aug. 23 and Aug. 26, Typhoon Aere brought about 973mm of rain, or half the annual average, to the reservoir. The amount of water that flowed into the reservoir came to about 700 million tonnes, three times more than its capacity.

Agency officials said the National Central University's an-alysis of satellite pictures taken after the typhoon indicated that 295 hectares of land in mountainous areas had collapsed since late last month. It was also estimated that more than 20 million cubic meters of silt, mud, driftwood and other debris was washed down to the reservoir. That amount was about 14 times the annual amount of silt deposits for the reservoir, officials said.

The turbidity of raw water at the reservoir increased dramatically to between 70,000 and 120,000 nephelometric turbidity units. However, the existing water-supply system can only deal with raw water with turbidity levels below 5,000 units. On Aug. 25, the water supply for residents in southern Taoyuan therefore began to shut down.

Although the government claimed that the water supply to Taoyuan Country was fully operational on Thursday, about 13,000 households on higher ground were still without water yesterday.

Wu said that Taoyuan residents require about 1 million tonnes of tap water a day. Yes-terday, the temporary water supply system set up since the typhoon struck remained 140,000 tonnes short of the target.

The Taiwan Water Supply Corp is continuing to provide water to affected users by truck.

Wu said yesterday that water resources around the country would be reviewed in the near future to stabilize water supply to not only homes but also the industrial sector. A task force will be set up soon to gather opinions from industry experts, academics and local governments.