Ecosystem Health Assessment Of Main Inflowing Rivers Of Taihu Lake

River, which is an important pathway of water cycle on earth and a necessary for the survival and development of human beings, has a crucial impact on the transmission of material and energy. With the vigorous development of industry-agriculture production and social economy, excessive utilization and unreasonable allocation of water resources lead to a serious shortage of water resources, river atrophy, destruction of water quality and a sharply fallen self-purification ability. With severe environmental problems, river ecosystem will directly influence the safety of the human life as well as the healthy development of social economy. Therefore, river ecosystem health assessment is useful for river ecological management, and can provide a scientific basis for achieving the sustainable utilization of river water resources and effective management of rivers.In this study,15main inflowing rivers health assessment were studied by the field investigation and data collection. Based on normal method of ecosystem health following the Stream Health Index (Index of Stream Condition, ISC) and River Health plans (River Health Program, RHP), the index system and the River Health assessment standards were established, the index system including:river hydrology, morphology, the condition of riparian zone, physical and chemical parameters of river water quality and aquatic biological indicators. A health assessment level standard was divided into four types, they were health, sub-health, sick, poor respectively according to a combination of quantitative analysis and qualitative analysis. AHP is used for determining the weight coefficient of each evaluation index. Means of equal addition and fuzzy comprehensive evaluation model were chosed to use for comprehensive evaluation of river water environmental health.The field investigation indicated that economic development, high density cultivation and industrial and agricultural emissions had a strong impact on river hydrology, morphology, the condition of riparian zone, river water quality and aquatic biology.Evaluation results showed that40%of15main rivers were sub-healthy,53%of15main rivers were poor, the others were pathological. Taige canal has the highest score of33.66, belonging to sub-healthy level; Liangxi river has the lowest score of16.22, belonging to poor level. This evaluation results demonstrated that approximately half of rivers were in a sub-health state. Accordingly, it’s necessary to strengthen river basin environmental management, to restore damaged river ecosystem and to develop a good circulation of river basin ecosystem which can promote the sustainable development of society.