Method of describing and diagnosing river health

摘要

River is a continual system from upstream to downstream and estuary, which is made up of riparian, water body and biocommunity in cross section. Every components of the system are interrelated and interacted on each other so that river system is an integrated dissipation system and has self-adjustment ability and self-suitable ability. However, the self-adjustment ability is limited because river system is an opening system which would be affected by many outside factors. When the influence degree of outside factors is larger than the capacity of river, river system would be ill. Only if every part of river system harmoniously operates, would river system be healthy. So healthy river system would be expressed by cooperation and order degree. It is obvious that calculating order degree is a kind of efficient way to diagnosing health of river system. In the method, it is the first objective to calculate the order degree of order parameters. Calculating the value of Index of Natural Structure Health and Index of Ecosystem Health and Index of social service Health is the second objective, which is obtained by use of Order Degree Model(ODM). Then index of general health would be reached by use of Entropy Method. As a case, health status of Anxi River has been diagnosed. It is result that health index of Anxi River is 0.713, belonging to Healthy state.