Study On The Method And Application Of Early Warning Index Inspection Review Of Mountain Flood Disaster In Small Watershed

The mountain flood disaster is one of the major natural disasters causing casualties,flash flood warning is an important method to prevent mountain torrents,critical rainfall is an important indicator of flash flood warning.Flood level?design rainstorm flood calculation method?the reasonableness of the selection of river roughness and ratio drop directly affects the calculation result of critical rainfall.To test the accuracy of critical rainfall,this paper from the four aspects of sensitivity analysis of mountain flood disaster parameters,inspection review of production and confluence flow,classification of small watershed,and review of critical rainfall,to carry out the research on the inspection and verification of the early warning index of mountain flood disaster in small watershed,and presents a systematic and complete system for the inspection and review of early warning indicators,and the application of some typical disaster prevention objects in Henan Province as research examples,obtained some research results with theoretical and applied value.The main contents and results of this paper are as follows:(1)Using Sobol sensitivity analysis method,the sensitivity of various parameters to the critical rainfall results in the water level flow inversion method was studied,and the influence degree of each part of the whole calculation system on the result of critical rainfall.Taking Hexigou Watershed in Anyang County as an application example,the results show that: the relationship between flow rate and water level flow has a greater impact on critical rainfall,the confluence part has less effect on critical rainfall.The results quantify the degree of impact of various factors,provide ideas for the inspection review method.(2)Based on measured rain and flood data,the applicability of typical small watershed runoff scheme is studied.Selecting the storage capacity distribution and runoff coefficient for the production flow calculation?standardized unit line for confluence calculation,building a higher precision production flow model for non data areas.Taking the PeiHe watershed in HeNan province as an example,the results show that: the constructed water storage capacity distribution flow model and standardized unit line confluence model,the calculation results are more accurate.This method is aimed at small watersheds with better data,re-determine the new production and distribution model,improve design flood calculation accuracy.(3)This paper proposes a verification method based on the K-means clustering analysis method in the no-data region production and convergence inspection.Select indicators that reflect the characteristics of a small watershed,by clustering indicator values,draw similar small watershed,the newly constructed confluence scheme parameters are transplanted to the missing data similar watershed,to test the accuracy of design floods.Taking Xinxian county of Henan province as an example,the results show that: the two kinds of results are more reasonable;in the classification results,Yuhe and Guanfan and Peihe Small Watershed belong to similar basins;apply the model to Yuhe River,by comparing the flow with the flood mark,the result of the constructed model is less error than the result of the analysis and evaluation method,it shows that the solution is feasible.This method solves the situation that the scheme of production and confluence can not be tested in the area where the mountain area is short of data,increased efficiency of inspection and review.(4)A method for determining the time for disasters and an inspection and verification method for early warning indicators based on disaster time are proposed,that is,the maximum amount of rainfall before the time of the recent flood disaster,analyze the degree of deviation from critical rainfall,direct inspection of critical rainfall accuracy;according to the field investigation,check the roughness and ratio,determine water level flow relationship,recalculate the confluence method after review,review Critical Rainfall Value.Using Yuhe and Guanfan Group as Application Examples,the results show that: the critical rainfall of 1h,2h and 6h in Yuhe group are all large;recalculation of critical rainfall value of Yuhe and Guanfan groups based on the rebuilt model and the relationship between water level and flow,and check it out,both deviations are significantly reduced,the critical rainfall is more accurate after review.In summary,the paper proposes a review system for early warning indicators for small watersheds,the technical route is correct,calculation method is feasible,the application results are reasonable,provided technical support for the inspection and verification of early warning indicators,have certain theory and practical application value.