Experimental Study On Typical Ground Runoff Genernation Process In North China Plain Area

Based on rainfall—runoff—irrigation and drainage in Hebei University of Engineering site as the backing,with the collected precipitation station of Handan city many years short duration heavy rainfall data for artificial rainfall simulation basis,in proving ground runoff plot scale analysis of the North China Plain are typical underlying surface runoff process of surface runoff and soil grains and its regularity,and build a runoff prediction model,test the conclusion can be further for the study of the North China Plain river basin scale hydrological process to provide the reference and basis,is also in the region of river basin runoff module of distributed hydrological model a beneficial attempt.The main results are as follows:(1)The average annual rainfall in the study area is 523.40 mm.Most of the rainfall occurs during the flood season in May and October,and the rainfall is more than 10mm/d in one year.The rainfall patterns of 292 sites were analyzed and concluded that the rainfall types in the study area were roughly divided into two types,heavy rain,short duration and long duration,and the probability of the former was about 3.5 times that of the latter.(2)According to the hydrologic data statistics and analysis of Handan city for many years as a result,this study selected the 0.77 mm/min,1.22 mm/min,1.56mm/min,and 1.78 mm/min four typical rainfall intensity and 53.6 min and 85.4 min and 127 min three typical rainfall duration,a total of 12 kinds of rainfall for artificial rainfall simulation experiment research.Calculation in 12 rainfall average rainfall evenness was 82.4%,of artificial rainfall simulation of rainfall by splash raindrop diameter research shows that the test of rainfall raindrop size distribution,meet the best raindrop size distribution function of a = 3.15I0.147 n = 3.27I-0.134.(3)Based on the actual measured data obtained by artificial simulated rainfall,a set of experiences of P+Wa?R rainfall runoff was established in accordance with the typical bedding surface of North China Plain.The empirical relationship between runoff coefficient(a)and rainfall(P),rain intensity(?)and rainfall early soil moisture(Wa)was established by regression equation.a = 0.006P + 0.180i+ 2.666Wa-0.950(n=12,R2 = 0.91)(4)Calculated by the measured data of artificial rainfall simulation rainfall reached a total of four field soil steady infiltration rate,although different times the initial infiltration rate,but the stability of soil infiltration rate tend to be about 0.10 mm/min.(5)It can be divided into two categories of the water withdrawal constant k in the North China Plain,and the channel runoff and surface runoff can be classified into one category,and the range of k values is 0.77-0.89,and the average value of k is 0.85.The average value of k was 0.92?0.98,and the average k value was 0.95.(6)By using the Horton infiltration model to describe the surface soil infiltration process and the Tank model to describe the underground runoff process,the overall fitting effect is better after the measured data verification.It can provide reference and basis for the study of the hydrologic process of the typical bedding surface of North China Plain.