| Mountain flood disaster is one of the most important natural disasters in China.With the increase of population density and social economy,mountain flood disaster has brought more and more harm to Shandong province and caused more and more economic losses.Therefore,it is extremely urgent to improve the accuracy of mountain flood warning.However,there are still serious technical problems in the current flood control situation and the application of early warning indicators: Critical rainfall calculation method to choose can’t adjust measures to local conditions,calculation parameter selection is not enough precise,different early warning time of disaster prevention objects can’t be effective early warning on regional whole,so this article mainly from the "how to calculate the warning index,what rules on warning index,index early warning system for different stages of an area to unify" three aspects to study.By using different methods,the early warning indexes of typical disaster prevention objects are determined comprehensively after comparative analysis.The sensitivity and correlation analysis were carried out for the main parameters involved in the calculation process to determine the influence degree of parameter change on the early warning index.Using the power function fitting method,the early warning indexes of some time periods under the same soil moisture condition are interpolated and extended to achieve the purpose of unified time series.The main achievements are as follows:(1)Taking the Shuyuan watershed of Qufu city as the main research area,two typical early-warning villages were selected and relevant parameter values were determined.The critical rainfall under the soil moisture conditions of 0.2Wm,0.6 Wm and 0.8 Wm were calculated by different methods.The comparative analysis showed that the calculated value of the same frequency backward method was small and the calculated value of the model analysis method was large.On this basis,the early warning index of disaster prevention object is determined comprehensively.(2)Involved in the process of early warning indicators calculation of main parameter sensitivity and correlation analysis,and use quantitative research results reflect the single factor the influence degree of the critical rainfall of mountain flood disasters,so as to determine the antecedent soil moisture,confluence parameter m,roughness n are negatively related with critical rainfall,CN value is mainly influence the flood peak discharge and flood volume,The lag time t LAG mainly affects the peak time,and different function relationships are used to fit the warning index value,which proves that the power function has the best fitting effect.(3)After comprehensive consideration of all aspects of the principle,the unified warning period is determined to be 0.5 hour,1 hour,3 hours,6 hours,12 hours,24 hours.The power function fitting method is used to carry out the time conversion for all the warning villages in Qufu City,taking the historical mountain flood disaster as the standard.The mean values of correlation coefficient R2 and Nash coefficient Ens were calculated to be 0.85 and 0.86,respectively,confirming the applicability of power function fitting.By analyzing and studying the period conversion of early warning index,this paper lays a foundation for realizing the unification of regional early warning index time series,which has a good application prospect in concrete flood control practice. |
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