Taiwan’s steep terrain and fast-flowing rivers make it difficult to retain water resources. In addition, rainfall distribution varies significantly across time and space. To enhance water resource utilization efficiency and mitigate uneven spatial distribution of rainfall, strengthening regional water source allocation has become a critical task to ensure stable water supply.
In the past, interregional pipelines have already been constructed, including: in northern Taiwan, water transfers from Taipei to Keelung and Banxin, diversion of Dahan River water southward to Taoyuan, and water transfers from Taoyuan to Hsinchu via trunk lines; in central Taiwan, water transfers from Taichung to Changhua, and from Yunlin to Changhua and Chiayi; and in southern Taiwan, water transfers from Tainan to Chiayi, as well as Tainan and Kaohsiung implementing joint water utilization through regional allocation pipelines.
In recent years, as climate change has intensified, the risk of drought has increased. For instance, during the severe drought from 2020 to the first half of 2021, no typhoons passed through Taiwan during the wet season, and average rainfall from June to September in major reservoir catchments reached only 20%–60% of the historical average. By the end of May 2021, the storage levels of three major reservoirs—Yongheshan, Liyutan, and Techi, which are crucial for supplying water to Hsinchu, Miaoli, and Taichung—had all dropped below 5%, resulting in extremely severe water supply conditions. Fortunately, the completion of the Taoyuan-to-Hsinchu trunk pipeline in February 2021 proved effective during the drought, ensuring water supply stability in the Taoyuan–Hsinchu region.
To address intensifying climate risks and build a resilient supply network, this Branch, in coordination with the Water Resources Agency (WRA), is advancing the Western Taiwan Water Supply Corridor String of Pearls Initiative, aimed at creating a stable nationwide water supply network. This includes north-to-south water diversion, bidirectional transfers in central Taiwan, and south-to-north water diversion. The related projects are as follows:
Northern Region Projects: Xizhi–Keelung interconnection pipeline (ongoing), Sanchong and Luzhou regional water supply network improvement (under construction), Second Phase of the Banxin Area Water Supply Improvement Plan (completed), Shimen Reservoir–Hsinchu raw water interconnection pipeline (under construction), and Taoyuan–Hsinchu trunk pipeline (completed).
Central Region Projects: Liyutan Water Treatment Plant northbound pipeline to Miaoli (under construction), Da’an–Dajia River interconnection pipeline (completed), Taichung–Yunlin regional water allocation pipeline improvement (under construction), and Zhuoshui Main Line–Northern Main Line interconnection (completed).
Southern Region Projects: Zhuoshui Main Line–Northern Main Line interconnection (completed), Zengwen–Nanhua interconnection pipeline (completed), Tainan–Kaohsiung interconnection pipeline (completed), and Nanhua–Gaoping interconnection pipeline (completed).
Cross-Basin Joint Operation of Water Sources: These measures will enhance the overall benefit of regular water supply, improve flexibility in allocation through raw and treated water interconnection pipelines, reduce supply risks, and ensure greater stability of the entire system (Fig. 1).