Taiwan may seal 967 wells in attempt to save high-speed rail

TAIWAN - As many as 967 deep wells in Changhua and Yunlin counties along the high-speed rail system will have to be sealed within 10 years if the system is to maintain safe operation, Minister Lee Hong-yuan of the Cabinet-level Public Construction Commission (PCC) said yesterday.

Lee made the remarks when presenting PCC's action plan concerning how to counter land subsidence threatening the safety of the high-speed rail system, during a meeting with representatives from the Water Resources Agency (WRA) under the Ministry of Economic Affairs (MOEA), the Taiwan Joint Irrigation Association (TJIA), and Taiwan Water Corp. (TWC) yesterday afternoon.

Lee said that the PCC will give the action plan to the Cabinet for approval within one week, and the plan will be enacted if approved.

Under the action plan, Lee said, a total of 24 deep wells in Changhua and Yunlin counties will be sealed by the end of this year, and at least 416 wells will be blocked, with the goal of having 967 wells sealed by the end of 2021.

After the goal is accomplished, as many as 490 million tons of underground water for agricultural and industrial use can be slashed, eventually leading to an increase of 200 million tons of water for above-ground use, according to Lee.

At the moment, there are around 51.4 square kilometers of land subsidence area in Changhua County, central Taiwan, which are sinking about 5.3 centimeters per year. The area will drop to 30 square kilometers by the end of 2016, with the subsiding pace declining to 3 centimeters per year then.

In Yunlin County, southern Taiwan, the subsidence area now reaches 397.6 square kilometers, with an annual subsiding pace of 6.8 cm. And the action plan aims to have the subsidence area shrink to only 178.2 square kilometers by the end of 2021, with the subsiding rate also slowing to 3 centimeters.

Lee stressed that once the annual pace of sinking drops to 3 centimeters from the current 5.3 centimeters in Changhua County and 6.8 cm in Yunlin County, then the safety of the high-speed rail system operation can be assured.

He continued that the land subsidence in both counties has been closely related to the operation of deep wells, and therefore all the wells to be sealed are deep ones, instead of shallow ones.

Lee called for farmers not to worry about the possible sealing of 180,000 shallow wells they operate. "I don't see any relation between the land subsidence and shallow wells."

After the deep wells are sealed, the Hushan Reservoir can serve to supply substitute water, while the recycling of water released by manufacturing plants in the counties should also be enhanced to increase the supply of water needed, Lee said.

After the action plan is approved by the Cabinet, it will be put into practice by the Council of Agriculture and the Ministry of Economic Affairs, at a total cost of NT$52.83 billion (S$2.2 billion), according to Lee.