The Analysis And Application On Region Flood Frequency In North Slope Of Tianshan.

Up to now,there is few widely agreeable or acceptable methods for resolving hydrological frequency analysis for an ungauged site.The density of hydrographic station network is so little that there isn't enough long series data even no hydrographic stations on some streams.With the development of society,we need to construct lots of small and medium hydraulic engineering,highway and bridge culvert projects spread over a considerable extent.However,enough hydrological data are usually in short even hardly any rainstorm information.Therefor to research calculation methods of design flood is of great significance.In this paper,flood frequency analysis on Tianshan north slope Xinjiang province is done with region frequency analysis combined index flood method aimed at the few information of this area and achieved good results.Based on previous studies,first attemption is made at fuzzy clustering in this area indexed by 3 statistical parameter reflected basin hydrological characteristics(namely liner average,liner dispersion coefficient and liner variation coefficient).This region is divided into two subareas where discordancy and homogeneity measure are made.To do regional flood analysis in the two subareas which have passed its discordancy and homogeneity test.The analysis estimate parameter of Pearson type III frequency distribution with L-moment method,getting regional growth curve.Then compare the two design results got by respectively observed data and regional flood frequency analysis,The results indicates that the reliability of regional flood frequency analysis is good. Evaluating index floods is needed for design site if you apply regional flood frequency analysis at ungauged area,so how to calculate index flood of design site at ungauged area is discussed.First,build the regression equation of total region to estimate the index flood briefly,then correct the preliminary result by displacing reference site.Finally calculate the design flood through regional growth curve and the index flood.The results indicates that regional flood frequency analysis method based liner moment is an effective way to evaluate design flood for ungauged site,which is worth of study carefully and spreading.