Study Of Eco-Envirobmental Flow For Medium And Small Mountain Rivers In Yunnan Province

With the proliferation of population and the rapid development of economy,water requirements of human beings are increasing fast. In order to exploit potentialwater resources, many regions began to manage rivers through hydrological control.These behaviors resulted in the degradation of river systems and triggered theresearch of eco-environmental flow. As to say Yunnan Province, where there are alarge number of hydrological projects constructed on medium and small mountainrivers, it is essential to evaluate the eco-environmental flow requirements to maintainan acceptable river condition.This dissertation discussed the concept and meanings of Eco-environmentalFlow and held the point that a minimum flow fails to ensure the health of riverecosystems. The magnitude, duration, frequency, timing and variability are essentialfactors of eco-environmental flows. There exit more than 200 eco-environmental flowmethodologies which were developed by different nations, therefore, each approachhave its own advantages, disadvantages and suitability. To calculate theeco-environmental flows of rivers in Yunnan Province, we have to develop or choosethose methodologies which are suitable to the characteristics of mountain rivers andset reasonable objectives.Eco-hydrological regionalization is the basement of eco-environmental flowevaluation. This dissertation analyzed its differences compared with ecologicalregionalization and water resources regionalization. Taking into consideration of thenatural and social features, this study conducted cluster analysis to Yunnan Provinceand did eco-hydrological regionalization by means of SPSS softwares. To developeco-environmental flow methodology for medium and small rivers in YunnanProvince, a case study was conducted to Yanggong River. A so-called CombinationApproach was developed and used to calculate eco-environmental flow requirementsof Yanggong River. Results were compared with those by Tennant, Q90 and GEFC methods and it is proved that Combination Approach is reasonable. And it beat othermethods by taking into consideration of both total amount and monthly flowdistribution.