Regional Synthesis Of M Value Of Confluence Parameter In Yulin Area Of Northern Shaanxi

There are few hydrological and meteorological stations in the north of Shaanxi,the density of hydrological station network is small,and the hydrological data is insufficient.In addition,in recent years,the construction of a large number of water conservancy projects and water and soil conservation projects in the north of Shaanxi has seriously affected the climate change and the underlying surface conditions of the basin,changed the law of production and concentration,and damaged the consistency of the obtained flow data series to different degrees,making it difficult to restore,and aggravating the problem The lack of data increases the difficulty of design flood calculation.The m-value of the confluence parameter is an important parameter in the inference formula.There are many factors that affect the m-value of the confluence parameter.In addition to the natural geographical factors of the basin,the confluence parameter is also restricted by the confluence duration and peak discharge.Due to the lack of clear understanding of its physical mechanism,there are some difficulties in the application of the reasoning formula method in the area without data.The calculation results are often with large errors and sometimes without solutions.Therefore,this paper analyzes and synthesizes the confluence parameters,further clarifies its physical significance,determines its single station comprehensive law and regional comprehensive law,so as to improve the reasoning The accuracy of design flood is calculated by formula method.The main conclusions are as follows:(1)Based on the understanding of zengshan experimental phenomenon,the flow mechanism of slope confluence is clarified.Combined with the flow velocity formula in hydraulics and the flow velocity empirical formula in traditional hydrology,the confluence parameters are deduced,and the physical mechanism of m value is further clarified.(2)Because the consistency of the flood peak flow sequence is destroyed,according to the idea of "tracing reconstruction method",the m-value formula is processed to deduct the influence of the runoff producing area,so that the flood peak sequence can be recovered smoothly,and the m-value formula suitable for Yulin area is further determined.(3)In this study,nine typical hydrological stations in Yulin City are selected to analyze and calculate the rainfall and flood data,plot and fit the relationship curve between peak discharge and concentration parameter m,and determine the single station comprehensive law and regional comprehensive law of concentration parameter.(4)The results show that after the improvement of m value of confluence parameter,the peak discharge calculated by the reasoning formula method is more close to the measured peak discharge,and the unsolved situation of the traditional reasoning formula method is solved at the same time.This method is more suitable to the actual situation and convenient to calculate.It can be used as a reference for the design flood calculation of small watershed without data in Yulin city.