River Water Quality Assessment in Selected Yangtze Tributaries: Background and Method Development

Water pollution is among the most severe environmental problems in China, particularly in the vicinity of residential and urban areas. In almost all Asian countries, river monitoring is predominantly based on the analysis of chemical data. However, biological data are a worthwhile addition for the determination of the long-term ecological status of rivers and are particularly well-suited in case of steep pollution and disturbance gradients. A tool for river water quality assessment using benthic invertebrates has been developed for selected tributaries of the middle reach of the Yangtze River. Site selection was supported by a preclassification considering physico-chemical and hydromorphological conditions. Following a stratified sampling design, 34 samples were taken in small and large streams in the subtropical mountainous area of western Hubei (湖北) (China) covering a pollution gradient, accompanied by an extensive field protocol on stream characteristics and (physico-) chemical water analyses. The proposed assessment system is computed as an average score per taxon. The challenge to further consider the additional impact from global change into the development of such tools is discussed.