In recent years, global climate change has resulted in longer typhoon season, sharply increasing cloudburst precipitation, drastically different river water flow between wet and dry seasons, and typhoon seasons causing more severe river erosion. Thus, after typhoon seasons, strong sunlight causes the areas of exposed land in downstream riverbed regions to increase, which create dust when blown by strong winds.
Accordingly, since 2011, the Environmental Protection Administration has coordinated with the Water Resources Agency, Council of Agriculture, and local governments to co-plan dust prevention and control operations. Different ministries and councils shoulder different powers and responsibilities and carry out varying work content and improvement goals. In 2013, 2017, and 2020, the Executive Yuan approved the River Dust Prevention, Control, and Improvement Plan (2012–2015), Air Pollution Control Action Plan, and Air Pollution Control Action Plan (2020–2023), respectively. In compliance with the action plans, the Water Resources Agency continues to engage in exposed riverbed land improvement-related operations. For example, in 2020, the agency added 258.85 ha of green cover, 1,649.7 ha of water cover, 788.36 ha of other cover (e.g., rice straw and xanthan gum cover) and methods, and 54.99 ha of new windbreaks, equating to a total improvement area of 2,750 ha and a 10% increase in improvement area compared with that in 2019.
This project referenced domestic and foreign dust prevention and control methods and proposed suitable and feasible methods after considering the characteristics of the domestic rivers. Additionally, the Environmental Protection Administration helped convene two project meetings and organize six onsite surveys; worked with relevant units to conduct onsite surveys; and, through conferences and coordination platforms, coordinated with all units to confirm the division of labor before and after flood seasons, determine the prevention and control methods as well as operation schedules for locations prone to generate dust, and review the river dust prevention, control, and improvement results.
On Apr. 23, 2021, the Environmental Protection Administration hosted the River Dust Prevention and Control Demonstration and Exchange Forum based on the theme of “river dust prevention and control-related challenges and innovations.” The goals were to provide an opportunity for river dust prevention and control-related units (i.e., the Water Resources Agency, Forestry Bureau, and local governments) to share their knowledge and experience in river dust prevention, control, and improvement, and survey the dust prevention and control measures adopted by the Zhuoshui River to serve as references for subsequent river dust prevention and control practices.
By analyzing river dust event-related suspended particulate matter concentrations and weather history, referencing professional meteorological data, and making judgment based on factors such as seasonal and meteorological conditions, the Environmental Protection Administration established dust forecast mechanisms. Moreover, by taking into account river characteristics and seasonal changes, the Environmental Protection Administration provided 1-day, 3-day, and 7-day dust forecasts during peak dust periods at the Zhuoshui River, Beinan River, Gaoping River, and Liwu River.
In 2020, 17 dust events were recorded, where the Zhuoshui River and Gaoping River accounted for nine and eight of such events, respectively; no dust events were recorded in any other rivers. Although the number of dust events in 2020 decreased by 17 times compared with that in 2019, the number of dust events at the Gaoping River was at a record high. Between Jan. and Sep. 2021, only one dust event took place (at the Zhuoshui River), which was a decrease of eight times compared with the same period in 2019.
Phase 1 of the Zhuoshui River Dust Prevention, Control, and Improvement Action Plan (2018–2020) decreased the number of dust events at the Zhuoshui River from 59 times in 2017 to only nine times in 2020, signifying a decrease of 85% and showing that by adopting the three methodologies (i.e., hydraulic engineering, forestation, and disaster prevention and responses) and by considering the time and location characteristics of the rivers, the Environmental Protection Administration was able to introduce dust improvement measures that were effective.
Because of the southwesterly flow and circulating currents in typhoons’ peripheries, in 2020, eight dust events occurred at the Gaoping River, which was a historic high. Therefore, the Environmental Protection Administration referenced the experienced gained by managing the Zhuoshui River and, on Jan. 4, 2021, came to the resolution to implement the Gaoping River Dust Prevention, Control, and Improvement Action Plan. In addition, the administration performed onsite surveys and held meetings to keep track of all units’ action plan implementation situations and difficulties that they had encountered.
