In order to better control the water quality and quantity data of the tributaries of the Donggang River Basin, the project team monitor partial drainage of Donggang River, including the upstream and downstream water bodies of the Forward-Looking Infrastructure Project (Niuchou River drain, Longjing River drain, Hsinghuabu River drain), as well as water bodies that do not meet water quality standards over the years, installing additional monitoring points for possible pollution sources (Meiji River drain, Hsinyuan drain and Hsichou River drain) to find out the source of pollution and carry out quality and quantity testing of branch drain, to establish and improve environmental monitoring and investigation. The data can be used as the basis for subsequent evaluation operations such as pollution reduction and pollution improvement effectiveness analysis. Based on the monitoring results of mainstream river water quality in Donggang River over the past 5 years, the project aims to set up 26 water quality detection points and 13 water quantity measurement points in polluted hot areas of key stations. During the period of project implementation, 141 water quality tests, 2 times each during the high and low water level period, and a total of 52 water measurements have been completed. According to the sampling results, biochemical oxygen demand (BOD), chemical oxygen demand (COD), and ammonia nitrogen of Niuchou River have a clear upward trend after the Chingliu Bridge, showing that organic pollutants lead to a decrease in the dissolved oxygen level in the water, which may be affected by the industrial wastewater. Escherichia coli also increased in Liucuo Bridge in August, which may be caused by sewage discharge, and suspended solid (SS) is roughly the same. There was an increase in Changhsing Bridge in June, which may be an engineering impact, biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solid (SS), and ammonia nitrogen increased in November after crossing Guanggou Bridge in Guangming Road. It indicated that organic pollutants lead to a decrease in the dissolved oxygen level in the water, which may be affected by livestock wastewater. Escherichia coli increased in the Northwest Second Bridge and the Guangming Road anonymous bridge, which indicated that livestock wastewater was discharged into the North Second Bridge and the Guangming Road anonymous bridge. According to the water quality test results of Longjing River, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were increased in Chaochou Bridge in June, showing that organic pollutants lead to a decrease in the dissolved oxygen level in the water. SS was increased in Chaochou Bridge, which may be affected by the engineering project. Escherichia coli was increased in the Wanluan Bridge, which may be caused by livestock wastewater. The impact caused by ammonia nitrogen pollution is about the same. The water quality test results in the Meiji River indicated that dissolved oxygen (DO), chemical oxygen demand (COD), chemical oxygen demand (COD), suspended solid (SS), ammonia nitrogen, and Escherichia coli have increased in the Minzu Bridge, showing that organic pollution has been discharged into the area after the Maolin Bridge, and the pollution is mainly caused by domestic sewage. According to the water quality inspection of Hsinghuabu River drain and Hsinyuan drain, biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia nitrogen and other pollutants are all high, showing that regional livestock wastewater and sewage pollution are severe problems. Niuchou River basin has two different monitoring sections between two different bridges. The first section is responsible for Niuchou River basin water purification engineering’s water quality, which is located between Fengnan Bridge and Changhsing Bridge. The second section is responsible for interception pipeline engineering’s water quality project in killer creek river in Pingtung City, which located between Chingliu Bridge and Liucuo Bridge. Water quality monitor indicated that suspended solid (SS) components have been changing over 15% between upper stream at Fengnan Bridge area and downstream at Changhsing Bridge. On the other hand, in the comparison of ammonia nitrogen percentage between Liucuo Bridge and Chingliu Bridge in the second section that indicated ammonia nitrogen elements have been detected higher amount about 15% higher at downstream at Liucuo Bridge. Furthermore, the biochemical oxygen demand (BOD) elements partially have been increasingly higher about 15 % at Liucuo Bridge more than Chingliu Bridge; however, not only due to the dramatically changes of biochemical oxygen demand (BOD) project but also, which domestic sewage disposal into stream would be major affected factors as well. Also, dissolved oxygen in water elements have been showed nothing changed. “Hsinghuabu Drainage Water Quality Purification Project” is responsible for high nitrogen wastewater treatment from Hsinghuabu River through local relevant equipment. According to the water quality monitor indicated suspended solid (SS) elements are 15% higher on the Gantang road, located at downstream anonymous bridge than upper stream on the Hsiawa Road, located at nameless bridge. As a result, it showed suspended solid (SS) quality is in unstable condition in this river. Besides July, 2019, in ammoniacal nitrogen part, there is more ammoniacal nitrogen found on the Hsiawa Road, anonymous bridge more than Gantang road, nameless bridge. There are also other major reasons that blowdown wastewater into the river from animal agriculture industries. Moreover, it would affect water quality monitoring; however, the quality of biochemical oxygen demand (BOD) have been changed in higher percentage in Gantang road, located at anonymous bridge more than on the Hsiawa Road, located at anonymous bridge. Dissolved oxygen in water quality has changed nothing in the condition. Longjing River drain, contained Longjing River and Wanluan River water quality purification project, which based on high riverbank’s water purification facility, collecting water quality samples from Longjing River and Wanluan River through the ditch. According to Water quality monitor indicated that suspended solid (SS) components have been changing over 15% between upper streams, located at Wanluan Bridge and downstream, located at Chaochou Bridge. Furthermore, the results of contamination degree of SS components are relatively low, which located in areas 1 and 2 in access roads, anonymous bridge. After the project began, it showed contamination degree of suspended solid (SS) components is very high to the river’s water quality. In ammoniacal nitrogen part, it’s test value numbers are 15% higher in downstream’ area at Chaozhou bridge more than upstream area’s at Wanluan Bridge, showing that the cause of its NH3-N deterioration mainly comes from the impact of livestock wastewater. Due to the rain impact erosion to make rain splash animals’ dung from farm to the river, which caused the whole river’s water quality has been changed badly. According to pollution reduction estimating based on QUAL2K simulation results, it indicated that Hsinghuabu drainage and Hsinyuan drainage’s contamination degree already meet the highest numbers, which archived three different contamination levels, low, medium and high levels. According the database of Hsinghuabu drainage and Longjing River’s agriculture industries resources that showed dissolved oxygen (DO) would be increased when ammonia nitrogen and the biochemical oxygen demand (BOD) reduced from water. After reduction of ammonia nitrogen and the biochemical oxygen demand (BOD), a river pollution index (RPI) calculation would not include dissolved oxygen (DO). After two rivers have already applied water treatments, which Longjing river flood diversion basin would be in uncontaminated condition, and Hsinghuabu drainage would only achieved low contamination degree in water pollution.

Donggang River, Niuchou River, Longjing River, pollution source, River water quality