Fri, Jul 16, 2004 - Page 2 News List

Kompasu won't bite, but plan for land use urged

EROSION Geologists say that the 921 Earthquake loosened so much gravel and stone that the nation needs to develop a plan to let the land stabilize itself

By Chiu Yu-Tzu  /  STAFF REPORTER

With the threat posed by Tropical Storm Kompasu lessening yesterday, the Central Weather Bureau lifted land and sea warnings related to the storm. However, recent flooding has prompted scientists and other experts to call for a well-designed national land-use plan.

The bureau, though lifting warnings yesterday, reminded residents in the central and southern parts of the country to be alert to possible damage that could be caused by heavy rain.

Meanwhile, geological experts suggested that people in central Taiwan, which was hit hard by the devastating 921 Earthquake, should be more alert to dangers posed by rain. At a public forum on damage resulting from Tropical Storm Mindulle, experts said that landslides and mudflows in central Taiwan, whose geological structure became much looser after the 921 Earthquake, might be common in the near future when heavy rains come.

"Millions of tonnes of unstable gravel and stones remain on slopes. It's normal for rainwater to flush it all down," said Hongey Chen (陳宏宇), a professor of geology at National Taiwan University (NTU).

Chen yesterday released the results of research about the amount of sediment that is carried away by rainwater. Taking as an example the Tachia River (大甲溪), which destroyed six power plants and numerous orchards on July 2, Chen said that before the 921 Earthquake the river carried about 8 million tonnes of sediment downstream each year. However, since the earthquake, the amount has increased to about 35 million tonnes.

After analyzing sediment erosion in several major river basins, Chen stressed that the public and the government must realize that the 921 Earthquake harmed the land in central Taiwan badly.

According to Chen, the Chuo-shui River (濁水溪) each year used to flush away 54 million tonnes of gravel and stone. But in 2001, the year Typhoon Toraji hit central Taiwan, about 143 million tonnes of gravel and stone were carried downstream.

After Typhone Herb in July, 1996, devastating landslides and mudflows created a considerable amount of sediment. Due to the 921 Earthquake, geological structures became more unstable. After Typhoon Toraji, thousands of tonnes of gravel and stones remained on slopes.

"It's time to give the mountains a rest," Chen said.

According to Wang To-far (王塗發), a professor of economics at National Taipei University, a national land-use planning project should be based on ecological equilibrium, generational justice, regional balance, tribal harmony and ways to mitigate tensions between humans and nature.

"To let the damaged land breathe, the government should provide a basis for limiting human activities in certain areas in the mountains and regulating land reserved for Aboriginals," Wang said.

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