Silt muddies drought-relief plan

Removing silt from reservoirs is a more effective way to solve water shortages than building new large reservoirs, Kuo Yao-chi (郭瑤琪), executive-general of the Cabinet's drought disaster-relief center, said yesterday.

But finding somewhere to put the silt is a problem, water resources officials said.

Kuo, who yesterday inspected the Shihmen Dam (石門水庫) in Taoyuan County, which supplies water to Taipei and Taoyuan counties, stressed the importance of maintaining reservoirs.

"We can't solve the problems if we keep demanding new reservoirs rather than maintaining existing ones," Kuo said.

Kuo urged water-resources officials to take advantage of the drought to remove as much silt as possible from behind the dam, saying that increasing the reservoir's effective capacity was the priority.

The drought in northern Taiwan has perplexed officials supervising major reservoirs.

By yesterday afternoon, the water level behind the dam had fallen to 199.39m, the lowest level since the dam was completed in 1964 and equivalent to just 3.43 percent of capacity.

Officials are hoping that a weather front expected to arrive today or tomorrow will bring heavy rain.

Lee Tieh-min (李鐵民), head of the North Water Resources Bureau under the Water Resources Agency (水利署), reported to Kuo about the maintenance of the dam, saying that about 55.46 million cubic meters of silt had accumulated in the reservoir since the dam was completed, of which 10.4 million cubic meters had been removed.

The dam's authorities are hoping to remove 700,000m3 of silt by the end of the year at a cost of NT$160 million, but a permanent site to dump the silt has not been found.

Lee told the Taipei Times that wet silt removed from the dam in the past had been sent to a pool to settle. The water is then drained from the pool into rivers and the dried silt placed at a temporary site near the dam.

"We proposed to the Taoyuan [County] Government early this year that dried sediment could be dumped in areas where soil had been excavated illegally, but we have received no response," Lee said.

Lee said refilling excavated sites was a good idea because it would prevent those sites from being polluted by illegally dumped hazardous waste.

Kuo said that the problem would be one of the topics for further discussion at a meeting being held today.

The current drought has prompted Control Yuan members, legislators and water experts to criticize the government for allowing too much silt to build up in reservoirs, reducing their capacity.

The Water Resources Agency, therefore, allocated NT$260 million to emergency projects to remove 45.2 million cubic meters of silt from the country's reservoirs.

"Offering funds is only the first step in removing the silt." Lee said. "We have never been told where we would be allowed to dump the sediments."

According to information provided by lawmakers last month, soil erosion caused by poor land management in mountainous areas has brought large amounts of silt down into the nation's reservoirs.

Recent statistics show that 277 million cubic meters of silt have accumulated in Taiwan's reservoirs. By the end of last year, lawmakers said, only 29.7 million cubic meters of silt had been removed.