Taiwan's Yuanshanzi Tunnel Activated for First Time This Year Amid Heavy Rains

Taiwan's Yuanshanzi Flood Diversion Tunnel initiated its first operation of 2026 early Tuesday morning, responding to significant rainfall impacting the Keelung River basin.

The diversion system activated at 6:30 AM after the Keelung River's upstream accumulated rainfall surpassed 300 millimeters. Water levels reached the 62.5-meter warning mark at 6:20 AM, prompting the diversion of floodwaters through the tunnel. This marks the 66th activation of the system since its completion in 2004, according to the Water Resources Agency's 10th River Management Office.

Lin Zhen-zhe, deputy director of the 10th River Management Office, stated that the heavy rains, influenced by the outer bands of Typhoon Mikla, saturated the upstream soil and caused river levels to rise rapidly. The management center's flood control personnel were deployed in advance to initiate the diversion mechanism. Preparations included thorough inspections of all diversion facilities, electromechanical equipment, the diversion tunnel, and the automatic gates for the sediment discharge channel, ensuring all systems were operational.

The management center will closely monitor the diversion process and provide real-time updates to the water resource center. Warning messages will be broadcast to residents and facilities in the surrounding areas via public address systems and electronic billboards to mitigate flood risks. The agency emphasized its commitment to ensuring the safety of nearby communities and infrastructure.

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The upstream mountain soil is already saturated and the water level is high. We dare not take it lightly and are on high alert.