Development of water and sediment quality management strategies for an urban river basin: a case study in Taiwan

The Love River basin is an important urban river basin in Kaohsiung City, Taiwan. The main cause of the river water quality deterioration is the discharges of municipal wastewaters into the river. In this study, river water analyses, sediment quality investigation, and water quality modeling were conducted to (1) evaluate the impacts of pollutant loadings on Love River and (2) develop basin management strategies. Geo-accumulation index and enrichment factor evaluation indicate that the sediments contained high concentrations of Cu, Zn, Ni, Cr, and Pb. Their concentrations were close to the effect range median implying heavy metals had adverse impacts on aquatics. The WASP (Water Quality Analysis Simulation Program) model was used to perform water quality modeling, and results indicate that sewage discharge from a sewage trench caused significant impairment of river water quality. An on-site aerated gravel-packed contact bed (CB) system was built in the riverside for 10% of river water treatment. The CB system could remove 52% of ammonia nitrogen (NH₃-N) and 64% of biochemical oxygen demand (BOD) from the influents. Modeling results show that an expansion of the CB system for 40% of river water treatment could further reduce NH₃-N and BOD concentrations and improve the water quality.