Taiwan reservoir saves $16 million in desilting costs with new tunnel

Taiwan's Shimen Reservoir is extending its operational life and saving millions thanks to the Amuping desilting tunnel. Since its completion in February 2023, the tunnel has been activated six times, most recently during Typhoon Mikra in June, removing a total of 1.06 million cubic meters of sediment.

Officials estimate that these desilting operations have saved the reservoir NT$530 million (US$16.1 million) by avoiding costly traditional methods like dredging, land excavation, and truck transport. The tunnel operates on a principle similar to a bathtub drain, creating an outlet at the reservoir's bottom to flush out sediment during typhoons and heavy rainfall.

The Amuping tunnel, a key component of Taiwan's Forward-looking Infrastructure Development Program, not only slashes desilting expenses but also offers significant environmental and safety benefits. It increases the reservoir's flood discharge capacity by 600 cubic meters per second and improves its overall flood control safety. Additionally, the flushed sediment replenishes downstream riverbeds, mitigating erosion and protecting coastlines.

Completed in November 2017 and finished in February 2023, the tunnel's design allows it to discharge sediment while simultaneously releasing floodwaters. This dual function is crucial for maintaining the reservoir's storage capacity and prolonging its service life, ensuring a more stable water supply for the region.