The Preliminary Study on Enhancement Strategy for Water Quality Management in Xiluo Irrigation Area of Taiwan
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3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41 THE PRELIMINARY STUDY ON ENHANCEMENT STRATEGY FOR WATER QUALITY MANAGEMENT IN XILUO IRRIGATION AREA OF TAIWAN Ke-Chun Lin1, Ying-Chun Lin2, Ching-Ru Tang2, Chong-Yuan Lin2 and Pi-Hui Suzi Chang3 ABSTRACT Yunlin County, known for its valuable agriculture and animal husbandry, is located at the south-central part of western Taiwan. Due to the geography, there is not enough surface runoff for irrigation purposes. Alternatively, the scheme of regional drainage reused for irrigation (RDRI) has been adopted by Taiwan Yunlin Irrigation Association (Yunlin IA) within certain irrigation areas, such as the Xiluo irrigation area, but some degradation of irrigation water quality occasionally happens. Aims of this study were (1) to understand how irrigation water quality was affected by RDRI, and (2) to propose enhancement strategies for Yunlin IA improving the irrigation water quality in the Xiluo irrigation area including the work-stations of Xiluo, Yinxi and Dayi. The affected areas of RDRI were accounted for 18.7% in Xiluo work-station, 31.1% in Yinxi work-station, and 100% in Dayi work-station, which was considered as the area seriously facing the problem of irrigation water quality deterioration. According to the industrial distribution in Yunlin County, animal waste could be the most influential sources polluting irrigation water. Since more than 80% of the livestock ranches in the Xiluo irrigation area were swine ranches, and many of them seemed not dealing with animal waste properly, the main pollution source might be the disposal of animal waste without appropriate pre-treatment. In conclusion, Yunlin IA should enhance the management on the discharge of animal husbandry waste via increasing waste pre- treatment, raising frequency of monitoring irrigation water quality, and cleaning irrigation ditch sediment while RDRI is applied. Along with the act of Taiwan Environmental Protection Administration on “livestock’s wastewater and solid waste recycling into the surrounding rural soils” started from 2017, co-operation between the livestock ranches and the surrounding agricultural land was strongly recommended to effectively promote the reuse of livestock waste and encourage farmers to practice recycling agriculture. Keywords: Regional drainage reused for irrigation (RDRI), Animal husbandry, Livestock waste, Swine ranch, Manure, Wastewater, Recycling agriculture 1. INTRODUCTION Yunlin County, located in the south-central part of western Taiwan, has an annual production value of agricultural commodities up to $2.6 billion, including$1.3 billion from crop farming and $1.1billion from animal husbandry (National Statistics, 2017). The total cultivated land area of Yunlin County is around 78,681 hectares, including 63,577 hectares of irrigation area managed by Taiwan Yunlin Irrigation Association (Yunlin IA) (Agricultural Statistics Yearbook, 2017; Taiwan Joint Irrigation Association, 1 Research Division III, Taiwan Research Institute on Water Resources and Agriculture (TRIWRA).19F, No.27-8, Sec. 2, Zhongzheng E. Rd., Tamsui Dist., New Taipei 251, Taiwan; E-mail: [email protected] 2 Irrigation Management Division, Irrigation and Drainage Section, Taiwan Yunlin Irrigation Association (Yunlin IA). 5F, No. 2, Xinghua St., Douliu City, Yunlin County 640, Taiwan; E-mail: [email protected] 3 Research Division III, Taiwan Research Institute on Water Resources and Agriculture (TRIWRA). 19F, No.27-8, Sec. 2, Zhongzheng E. Rd., Tamsui Dist., New Taipei 251, Taiwan; E-mail: [email protected] 1 3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41 2016).Because Yunlin County has long been one of the main sources for agricultural products in Taiwan, the quality of irrigation water supplied by Yunlin IA is supposed to be important to guard food safety and human health. Yunlin IA has already developed a mechanism to monitor and quickly respond to any pollution incident happening in irrigation water. The mechanism includes a regular monitoring network on water sources and specific sites along the irrigation ditches (Irrigation Water Quality Management Guidelines, 2017). Moreover, before any non-polluting waste water can be discharged into a ditch managed by Yunlin IA, a thorough application process must be completed and then approved (Agricultural Irrigation Water Quality Protection Act, 2013). During the period of discharging with permission, the discharged wastewater will be regularly checked by Yunlin IA in order to confirm that all standards of irrigation water quality have been complied with (Guidelines of Irrigation Water Quality Monitoring and Evaluation, 2017).These are good strategies to avoid most pollution incidents seriously affecting irrigation water quality. Due to the geographic conditions of Yunlin County, it is difficult for Yunlin IA to collect enough surface runoff for irrigation purposes. In order to meet with the requirement of irrigation, Yunlin IA applies the scheme of regional drainage reused for irrigation (RDRI) in certain irrigation areas, such as the Xiluo irrigation area, which is one of the major cultivated land areas in Yunlin County. Nevertheless, there are approximately 1.5 million swine as livestock in Yunlin County (Quantity Report of Swine in Taiwan, 2018), and in the Xiluo irrigation area, more than 80% of the livestock ranches are swine ranches (Registration and Management System of Livestock Ranches, 2019). As animal husbandry is one of the main sources of agricultural waste, both in water and solid types, the swine ranches have been considered to discharge an extremely large amount of waste into environment (The Green National Income Account, 2017).Although many of livestock ranches in the Xiluo irrigation area discharge their effluent into regional drainages rather than the ditches managed by Yunlin IA, the waste would still affect the downstream irrigation water quality and annoy the nearby residents (Gerendáset al., 1997). The risk of degrading irrigation water quality would be increased by RDRI. According to Yunlin IA’s long-term monitoring data of irrigation water quality, the Xiluo irrigation area has been one of the seriously influenced areas by RDRI. With the intention of clarifying the potential pollution sources and evaluating the influential level of RDRI in the Xiluo irrigation area, this study was carried out. The Xiluo irrigation area investigated in this study was composed of three work- stations including Xiluo, Yinxi and Dayi. Aims of this study were (1) to clarify how irrigation water quality was affected by RDRI, and (2) to propose enhancement strategies for Yunlin IA improving the irrigation water quality in the Xiluo irrigation area. Firstly, the area influenced by RDRI in the Xiluo irrigation area was evaluated by work-station. Secondly, the industrial distribution in the Xiluo irrigation area was analysed by industrial type. Thirdly, a series of sediment in Yunlin IA’s ditches was sampled and the heavy metals of arsenic (As), mercury (Hg), lead (Pb), cadmium (Cd), zinc (Zn), copper (Cu), chromium (Cr) and nickel (Ni) were examined to verify whether livestock waste causing degradation of irrigation water in the Xiluo irrigation area. Lastly, swine ranches within the Xiluo irrigation area were systematically selected and a questionnaire survey was conducted to give an overall picture of the on-site waste management there. From the results of this study, comprehensive enhancement strategies would be provided to improve irrigation water quality of RDRI in the Xiluo irrigation area. Hopefully, these enhancement strategies could also be applied to other areas of Yunlin I Ain the future. 2 3rd World Irrigation Forum (WIF3) ST-1.1 1-7 September 2019, Bali, Indonesia W.1.1.41 2. METHODS 2.1 Analyses of irrigation Water Quality A data set of five-year (from 2013 to 2017) monitoring of irrigation water quality in the Xiluo irrigation area, which included the work-stations of Xiluo, Yinxi and Dayi, was analysed. There were 209 monitoring points and 4,749 monitoring data of irrigation water indicators including water temperature (WT), pH value and electrical conductivity (EC).In this study, irrigation water quality monitoring data of Yunlin IA in 2013 and 2017 were screened out and calculated for annual averages of WT, pH and EC by work-station. The averages of each indicator in 2013 and 2017 were respectively shown on maps of the Xiluo irrigation area using the software of QGIS 2.18.13 (QGIS Development Team, 2016) and investigated changes in each work- station. 2.2 Analyses of Potential Pollution Sources According to the regulation in Taiwan, it is necessary to be approved by Irrigation Associations before any non-polluting wastewater can be discharged into a ditch managed by Irrigation Associations (Agricultural Irrigation Water Quality Protection Act, 2013). From the quarterly report updated in July 2018, there were161 dischargers allowed to discharge into the ditches in the Xiluo irrigation area. The register of industrial type” (i.e. manufacture, livestock ranch and domestic sewage) of these dischargers were analysed. In order to diagnose any potential access and pathway of pollution, the locations of the dischargers were shown on a map of the Xiluo irrigation area using the software of QGIS 2.18.13(QGIS Development Team, 2016). 2.3 Sampling of Sediment in The Irrigation and Drainage Ditches Due to the animal husbandry and livestock ranches could directly/indirectly discharge wastewater into neighbouring irrigation or drainage ditches managed by Yunlin IA, a series of sediment in ditches was sampled and analysed to serve as evidence of the influence of RDRI. 10 of the sampling sites either conducted RDRI or located along the main irrigation and drainage ditches in the Xiluo irrigation area were chosen:Xiluo drainage ditch (1M), Xinshe irrigation ditch (2M), Dinnan irrigation ditch (3M), Dayilun drainage ditch (4M), Dazhuang main irrigation ditch (5M), Xinzhuangzi main drainage ditch (6M), Central drainage ditch (7M), Bajiating main drainage ditch (8M), Nandayi main drainage ditch (9M) and Tianwei main drainage ditch- Xindian irrigation branch (10M).