Study On Theoretical Framework And Diagnosis System Of River Health

River health is an essential condition to support life existing and developing. Research on river health is a key project that closely relates to orderliness, health and sustainable development of human society. The theoretical framework and diagnosis system of river health have been studied in the paper based on the concept of river system. The main works and conclusions are as following:(1) The theoretical framework to river health research was established. That river system should be looked as study objective of river health was proposed based on the analysis of the existing concepts of river health, and a new definition of river health on river system was introduced. Its connotation and characteristics were analyzed. The temporal and spatial scales of river health research were put forward. The diagnosis system framework to river health was established which based on the category of influence factors, and research contents and methods were summarized.(2) The comprehensive assessment indicator system to river health was established. Its spatial scale was river segment and the principles used to river division were proposed. The indicator system was established which includes four levels, i.e. aim level, standard level, index level and variable level. Twenty-eight indices were chosen on the base of endogenous factors of river health. The assessment contents included river construction, ecological and environmental function and social service function. The methods used to collect index data were sum up.(3) The comprehensive assessment model to river health was established. Analytic Hierarchy Process and grey relation analysis method were used to establish the model on the base of analyzing the common multiple criteria comprehensive assessment method and weighting method, in which grey relation analysis method was improved, a new expression of grey relation coefficient was presented and its rationality was analyzed. The health threshold values of the indicator were proposed.(4) The model on main influence factor analysis to river health was established. The indicator system used to main influence factor analysis was established and the function relations of the model were determined based on the analysis of exogenous factors and the relation between endogenous factors and exogenous factors. Partial least-squares regression was used to establish the model. A table was designed to express the result of main influence factor analysis. A simplified method of the model was deduced which could be used to determine main influence factors in a catchment corresponding to assessing river section.(5) The application research of the diagnosis system on river health carried out. The system was applied to diagnose the river health condition and main influence factors of the Lancun-Yitang reach in the middle Fenhe River which include comprehensive assessment model and main influence factors analysis model. The control measures were proposed.