Mon, Oct 06, 2025 page8

• Properly using floodwash material

  • By Chen Wen-ching 陳文卿
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  Heavy rains from Super Typhoon Ragasa on Sept. 23 caused a barrier lake in Hualien County’s Mataian River (馬太鞍溪) to burst, with the mud from the floodwaters piling up like mountains and spreading over several kilometers. The proper management of this mud is a critical issue.

  The mud that surged out of the barrier lake and was cleared from the river channel and surrounding areas came from landslides of rocks and soil from the mountains. Taiwan’s eastern region has many cement factories, because it is difficult to extract the raw materials needed for cement production in the west, making Yilan and Hualien counties sources of material. Mining requires permits from local governments that regulate mining duration, area and extraction volume.

  Ragasa washed down tens of millions of tonnes of debris, which could supply cement factories with raw materials for several years.

  This is similar to what happened after Typhoon Morakot in 2009, when a massive amount of sand and gravel washed into Pingtung County’s Donggang (東港) and Laonong (荖濃) river basins. Afterward, many sand and gravel quarries were established in the Pingtung and Greater Kaohsiung areas, becoming major sources of construction materials for central and southern Taiwan.

  The government should implement the following measures to manage the mud and debris from the barrier lake.

  First, suitable locations should be selected as centralized storage sites for soil and rock resources, then equipped with facilities such as fences and drainage systems. This would not only prevent materials from being washed back into roads or rivers and cause secondary pollution, but also allow for the proper management and reuse of these resource materials. Unauthorized people should not use these materials without permission.

  Second, qualified sand and gravel operators should be selected to manage the sites. After removing waste, the soil and rock should be properly classified and sifted before being sold at public auction.

  Local cement factories with mining permits should be encouraged to purchase and use these materials. Cement and concrete production should also prioritize using these disaster-created soil and rock, and limit the volume of new extraction. Cement factories and construction materials companies could also label their products as made from post-disaster resources, thereby aligning with environmental, social and governance principles, and contributing to the development of environmental sustainability.

  Last, the government should prioritize using building materials produced from these post-disaster resources during public construction projects. This could be a “heavenly compensation” in the aftermath of a natural disaster.

  Chen Wen-ching works in environmental services.

  Translated by Kyra Gustavsen
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