Government agencies take action to ensure water storage facilities provide a clean and stable supply of the invaluable resource.
Dredgers and excavators busily remove sediment from Zengwen Reservoir in southern Taiwan’s Chiayi County, a job picking up pace at artificial lakes across the country that face a growing risk of silting up. By the end of 2019, approximately 26 percent of Zengwen’s 748 million cubic meter capacity was choked with unwanted materials despite the largest water storage facility in Taiwan having cleared out an average of 2.43 million cubic meters of sediment annually from 2017 to 2019, up from 1.39 million cubic meters during the 2009-2016 period.
“It’s quite difficult to build new reservoirs today, so the focus is on ensuring the longevity of existing ones,” said Chien Chao-chun (簡昭群), Conservation Division chief of the Water Resources Agency (WRA) under the Ministry of Economic Affairs. “Concern over environmental damage caused by dam construction has grown over time, and relocation of people living on land slated for flooding has become more challenging,” the official said.
Desilting efforts like those at Shihmen Reservoir in northern Taiwan are picking up pace at water storage facilities around the country. (Photo by Jimmy Lin)
Taiwan has 95 reservoirs and weirs—the majority of which are managed by the WRA and state-owned entities like Taiwan Water Corporation and Taiwan Power Company, the country’s largest providers of the respective utilities—but no dams have been constructed since Hushan Reservoir in the western county of Yunlin began operating in 2016. Maintaining the health of these facilities is no easy task as the region is prone to natural disasters like typhoons and earthquakes, which can wreak havoc on infrastructure.
In 2009 Typhoon Morakot alone brought 91 million cubic meters of sediment into Zengwen, prompting the government to build a desilting tunnel that commenced functions in 2018. Similarly, Typhoon Soudelor caused a record high level of turbidity in 2015 in Nanshi Creek, which converges downstream with Beishi Creek to form Xindian River, the primary source of drinking water for Taipei City and much of New Taipei City. In response, Taipei Water Department (TWD) began construction on a tunnel bringing water directly from Beishi to treatment facilities.
To reverse the degradation of reservoirs and ensure stable water supplies, the government launched the Forward-looking Infrastructure Development Program (FIDP) in March 2017. A comprehensive initiative aimed at meeting Taiwan’s development needs for the next 30 years, the program speeds up desilting efforts at facilities countrywide. Among other projects, it has allocated NT$800 million (US$28.1 million) to finance the NT$2 billion (US$70.2 million) tunnel at Beishi. “The climate is set to become more extreme in the future, so this is definitely money well spent. Each suspension of water due to weather takes a considerable toll on the economy,” said Chen Wei-cheng (陳維政), deputy superintendent of TWD’s engineering division.
A dredger sets to work on Chiayi County’s Zengwen Reservoir in southern Taiwan. With a capacity of 748 million cubic meters, the reservoir is the largest in the country. (Photo courtesy of Southern Region Water Resources Office of the Water Resources Agency)
Proactive Measures
Conserving watershed areas—which cover 1.2 million hectares, or 34 percent of Taiwan’s land—is another major component of FIDP. Much of the task is performed by the Cabinet-level Council of Agriculture (COA), whose Forestry Bureau and Soil and Water Conservation Bureau (SWCB) are respectively responsible for woodland along the upper reaches of rivers and slopes above the timberline.
The agencies primarily focus their energies on reforesting collapsed areas, shoring up replanted locations with nets and wattles to boost chances of successful regrowth. “This is the most farsighted job when it comes to bringing a reservoir back to health,” said Lin Jen-yang (林鎮洋), director of the Water Environment Research Center at National Taipei University of Technology. “A watershed with good forest coverage retains soil that would otherwise wind up in reservoirs and is capable of storing large amounts of water.”
According to SWCB, 29,000 hectares of land currently await restoration, a portion of which is highly inaccessible terrain. While the government previously relied on the forces of nature to return such areas to their original states, the COA has launched an experimental project utilizing unmanned aerial vehicles to speed the process up. From April to June 2019, the Forestry Bureau sent out single-rotor drones to distribute 210 kilograms of seeds over a collapsed forest deep in the mountains of northern Taiwan’s Yilan County. A survey conducted in August 2020 showed the vegetation coverage rate in the area has risen from 31 to 53 percent. Based on these encouraging results, the bureau is drawing up plans to upgrade the mission with more sophisticated equipment.
A tunnel under construction at Beishi Creek downstream from Feitsui Reservoir will greatly reduce the risk of weather-induced water shortages for Taipei residents. (Photo by Chin Hung-hao)
COA agencies also perform the essential task of preventing sand in waterways from migrating downstream. This is primarily accomplished through the construction of groundsill works, elevated structures spanning a river to slow the current in line with ecological engineering concepts. The most recent example is a set of structures completed in 2020 by SWCB on Alibudong Creek, which feeds Jiji Weir in central Taiwan’s Nantou County. Featuring five groundsills and ecofriendly pathways for animals, the project has already successfully prevented 60,000 cubic meters of mud from reaching Jiji’s reservoir, thus protecting water resources for farms, households and factories in neighboring Changhua and Yunlin Counties.
Ensuring Purity
While the health of all reservoirs is important, particular attention is paid to the 22 that chiefly provide drinking water to households. Since 2017 water quality is tested on a monthly basis, an increase in frequency from the previous quarterly standard. To ensure water meets criteria for human consumption, agencies at the national and local levels are taking steps to minimize potential sources of pollution.
The civil engineering project on Alibudong has effectively prevented over 60,000 cubic meters of silt from entering Jiji Weir. (Photo courtesy of Nantou Branch of Soil and Water Conservation Bureau)
Leading the charge is Taipei Water Management Office (TWMO) under the WRA, which is responsible for jointly managing Feitsui Reservoir’s 717-square kilometer watershed with the COA as well as the Cabinet-level Council of Indigenous Peoples and the Ministry of Finance’s National Property Administration. In the late 1980s, TWMO took major steps toward improving the reservoir’s water quality by banning pig farming and boating around the lake. At the same time the government began working on sewage pipelines connecting households in the area to treatment facilities. Homes in remote locations were equipped with mini-systems for processing their own wastewater. Today, sewage produced by 75 percent of all residences in Feitsui’s watershed is treated before being released into waterways, with the goal of reaching 100 percent in the near future.
Reducing contamination from agriculture is also high on the agenda for TWMO. It is now promoting the installation of systems using natural materials like vegetation or pebbles to filter runoff containing fertilizer and pesticide residue that leaches from fields during heavy rainfall. “We’ve also been encouraging people to adopt organic farming. The use of chemicals harmful to the human body has already been banned, but we’re sparing no effort to further improve water safety,” said Chou Wen-shang (周文祥), director of TWMO. As a result of the agency’s efforts, levels of phosphorus and nitrogen—two major culprits of eutrophication—have been greatly lowered.
Wushantou Reservoir in southern Taiwan’s Tainan City is a beneficiary of government efforts to ensure water storage facilities can provide clean and stable supplies. (Photo by Chin Hung-hao)
Feitsui Reservoir has become a model example of water resource management in Taiwan. Meanwhile, the WRA has completed its 2020 survey on reservoir conditions around the country, using seven newly adopted indicators aimed at thoroughly assessing a body of water’s health, including forest coverage in watershed areas, sediment accumulation rate and the level of eutrophication.
“The government used to focus mainly on the structural safety of dams, but since the mid-2000s it’s paid growing attention to whether reservoirs can provide a steady supply of clean water,” Chien said. The findings of the latest survey have been sent to the relevant authorities so they can draw up plans to address any weaknesses.
With the stability of reservoirs ensured by a range of proactive approaches—from desilting and forest restoration to comprehensive health checks—the country has every reason to anticipate a worry-free future regarding water supply. “Taiwan is moving in the right direction,” Lin said. “It’s good to take action after something happens that alerts us to the vulnerability of our water sources, but it’s truly wise to take preventive measures.”
Write to Oscar Chung at mhchung@mofa.gov.tw