Abstract: River health comprehensive assessment index (RHCAI) is integrating the  conditions of river, such as hydrology, physical morphology,riparian zone, water quality parameters and aquatic organisms,for assessment of  health status of rivers. Compared with river hydrology index and other indices, the index of aquatic organism is too simple to quantify the health status of complex river ecosystem. Hereby  EPT (Ephemeroptera, Plecoptera and Trichopter) relative abundance index and family biotic index are added as secondary indices of aquatic organism index. Both the original and modified RHCAIs were used to  evaluate river health of Changjiang River for comparison.Results show that the river was generally good in health with all scores>60 and all the observation sites were either in good health or subhealth.However,it was also found that the health condition of the river declined significantly with the flow from the upstream to the downstream of Changjing River and its major tributary--Donghe River.All the three sites being the lowest in RHCAI scores were found in the main stream of Changjiang River,while the sites being the highest in RHCAI scores were located in the headwater region.These findings demonstrate that the modified RHCAI is able to show slight diferences between the observation sites in health status,and fully and objectively reflect health condition of rivers.    

Key words: river health comprehensive assessment index(RHCAI), Changjiang River, river ecosystem, aquatic organism