A new criterion for defining the breakpoint of the wetted perimeter-discharge curve and its application to estimating minimum instream flow requirements  

作　　者：MEN BaoHui LIU ChangMing LIN ChunKun 

机构地区：[1]National Engineering Laboratory,for Biomass Power Generation Equipment,Renewable Energy Institute,North China Electric Power University,Beijing 102206,China [2]Key Laboratory,of Water Cycle and Related Land Surface Process,Institute of Geographical Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China [3]College of Water Science,Beijing Normal University,Beijing 100875,China

出　　处：《Science China(Technological Sciences)》2012年第10期2686-2693,共8页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No. 50809027);the Fundamental Research Funds for the Central Universities (Grant No. 11MG15);the Open Research Fund Program of State Key Laboratory of Water Resources and Hydropower Engineering Science (Grant No. 2009B050)

摘　　要：The wetted perimeter method(WPM) is used in hydrology and hydraulics to calculate instream flows.The WPM requires few data.It requires only the values of the wetted perimeter,flow and water level,which can be obtained from the hydrologic stations of the river in question.In addition,the WPM is not limited by the impacts of human activities on the river runoff.Therefore,this method is generally suitable for the current conditions in China.However,the process of applying the WPM involves two key aspects:how to plot the curve describing the relationship between the wetted perimeter and the discharge and how to confirm the breakpoint of the wetted perimeter-discharge curve.The traditional method is to calculate the curvature or the slope of the wetted perimeter-discharge curve to obtain the minimum flow.According to this method,the minimum flow corresponds to the point of maximum curvature or to the point at which the slope of the curve is equal to 1.The wetted perimeter-discharge curve of a natural river is only part of the complete curve.Thus,the instream flow calculated by the traditional method is the minimum or maximum discharge.The new criterion for defining the breakpoint of the wetted perimeter-discharge curve is that the slope at the breakpoint is a relative maximum,the second-largest slope.The discharges at the breakpoints corresponded to the minimum flow levels required to maintain the ecological function of the river.The minimum instream flow requirements(MIFRs) of four typical reaches,Zhuba,Daofu,Ganzi and Zumuzu hydrological stations on the West Course of the First Stage Project of the South-North Water Transfer Project(WCFSPSNWTP),are calculated using an improved wetted perimeter method(IWPM).The results show that the MIFRs of Zhuba,Daofu,Ganzi and Zumuzu are approximately 9.06-14.5 m 3 s-1,20.7-43.5 m3 s-1,38.8-77.2 m 3 s-1 and 40.4-59.5 m 3 s-1,corresponding to 11.7%-33.9%,14.2%-37.6%,12.4%-28.4% and 17.5%-30.2%,respectively of the annual average flow(AAF).These MIFRs can maintain good ecological fun

关 键 词：wetted perimeter method SLOPE CURVATURE the West Course of the First Stage Project of South-North Water Transfer Project （WCFSPSNWTP） Tennant method 

分 类 号：TV133[水利工程—水力学及河流动力学] TM912.1[电气工程—电力电子与电力传动]