Research On River Health Assessment And Ecological Operation Based On Essential Hydrologic Factors

Rivers are providing various important ecosystem services to human society,such as water resources,hydropower and so forth.However,riverine ecosystems are among the most fragmented,degraded and threatened ecosystems worldwide resulting from widespread human disturbances over the recent past.With growing concerns about riverine ecosystems,river health conservation has become an increasingly hotspot science.The quantification of river health status is one of the key issues of river health conservation.The interactions among components of rivers are often ignored in existing researches,resulting in the distortion of quantification.Ecological operation of reservoirs is an important way for river health conservation.However,the direct application of river health assessment metrics in ecological operation is very limited.On the basis of essential hydrologic factors of riverine ecosystems,river health assessment method and ecological operation model are explored in this dissertation.The achievements can benefit river health conservation both in theory and practice.Firstly,the social background of river health conservation in China is studied.The social concern about aquatic ecosystems from 1950~2000 in China is quantified.The results show that a good social background for river health conservation has been formed.Eco-compensation provides an important way for the public to participate in the conservation of aquatic ecosystems.The relationship among compensatory mechanisms in China and abroad is analyzed.This study reveals the defects of eco-compensation in China in responsibility fulfillment,effectiveness and so forth.The causes of defects are analyzed and suggestions for the future are posed.It is found that the function of eco-compensation in river health conservation has been impaired for the lack of quantization mechanism.To quantify the river health status,a fuzzy logic method for river health assessment and sensitive factor diagnosis is developed.After designing an index system of river health assessment,trend metrics are developed which represent both the historical trends and current status of original metrics to resist risks.The interactions among metrics are set as influencing factors of river health assessment through fuzzy logic.A fuzzy logic river health assessment model is built.It is proved to be very sensitive to the variation of single metrics.A river health restoration sensitive factor diagnosis method is developed to figure out metrics with the best short-term restoration effects.Afterwards ecological operation model focusing on river health is explored.The target of ecological operation is to minimize the hydrologic alteration in this dissertation.Fifteen discontinuous and nonlinear metrics,which can describe key features of flow regime,are used in ecological operation.Then,a two-stage two-level reservoir operation rule is designed to coordinate the water supply benefits of different periods and different water users,and reduce the computational complexity.A reservoir ecological operation model is built and solved successfully using the genetic algorithm.Finally,methods and models developed in this dissertation are applied in the Yellow River.The health status of the mainstream of the Yellow River in 2010 is assessed by the fuzzy logic river health assessment model,and the sensitive factor for restoration is diagnosed.An ecological operation model for the Wanjiazhai Reservoir is built to analyze the competitive relationship between social economic benefits and ecological benefits of water supply.The advantages of the reservoir ecological operation model are revealed with comparison to the standard operation policy and the open discharge policy.