Pollutant sources investigation and remedial strategies development for the Kaoping River Basin, Taiwan

The Kaoping River Basin, located in southern Taiwan, flows through approximately 171 km and drains towards the South Taiwan Strait. It is the largest and the most intensively used river basin in Taiwan. Based on the results from the pollutant sources investigation and water quality analysis, the main water pollution sources of the Kaoping River were livestock wastewater from hog farms, municipal wastewater, industrial wastewater, leachate from riverbank landfills, and non-point source (NPS) pollutants from agricultural areas in the upper catchment. Concern about the deteriorating condition of the river led the Government of Taiwan to amend the relevant legislation and strengthen the enforcement of the discharge regulations to effectively manage the river and control the pollution. The following remedial strategies have been taken to improve the river water quality since 2001: (1) hog ban in the upper catchment of the Kaoping River Basin, thus, 510 thousand hogs have been removed/relocated; (2) removal of riverbank landfills; (3) enforcement of the industrial wastewater discharge standards; (4) sewer system construction in five cities along the river corridor; (5) application of best management practices for NPS pollutant control; (6) application of natural wastewater treatment systems (e.g. land treatment, constructed wetland, overland flow, riverbank sedimentation/aeration pond) for domestic wastewater treatment in rural areas; and (7) construction of the watershed geographical information system (GIS) and real time water quality monitoring system to effectively monitor and manage the watershed. Recent water quality investigation results indicate that the biochemical oxygen demand (BOD) and nutrient loadings to the Kaoping River have been significantly reduced and the water quality has been improved after the implementation of the remedial strategies described above. Results and experience obtained from this study will be helpful in designing the watershed management strategies for other similar river basins.