Flood Frequency Design In The Lower Of Yellow River By Regional L-Moments Method

With our economic development, loss of flood disaster will become more and more serious. However, methods of design flood don't have updated when hydraulic engineering projects are more than ever.L-moments are a new system based on "probability weighted moments (PWM)," and they are more robust than commom moments. NOAA/NWS/Office of Hydrologic Development-Hydrometeorological Design Studies Center (HDSC) in U.S.A. uses regional L-moments analysis to design precipitation and get many appropriate results.The paper expatiates on theory about L-moments and regional L-moments analysis method. Using regional L-moments analysis method designs flood frequency in the lower of Yellow River. For annual maximum series (AMS), screening of the data has been carried out by employing Discordancy measure (Di) in terms of the L-moments. Homogeneity of the region has been tested using the heterogeneity measure (H) by carrying out 500 simulations using the four parameter Kappa distribution. Because H is negative, the 8 sites are correlated. As a result, we adopt 5 sites as a regional and design flood values are in 5% scope with value of design flood at 8 sites. Therefore, we still adopt the region of 8 sites.It has been observed that the data of 8 sites constitute a homogeneous region. Comparative five distribution, GEV, GNO, GLO, GPA, PE3, it has been founded that GEV distribution is the robust by regional L-moments analysis studies.For partial duration series (PDS), the 8 sites still compose one homogeneous region. Comparative the result with outcome of annual maximum series, there's a connection between the results of two different series. The ratio is among 1.0~1.3.Finally, it gets some conclusion and gives some suggestion.