一个用于瞬时单位线参数更新的递归公式的推导及应用  

Derivation and Appropriate Application of a Recursive Equation for Parameter Updating of the Instantaneous Unit Hydrograph

作　　者：董晓华[1] 刘冀[1] 邓霞[1] 薄会娟[1] 

机构地区：[1]三峡大学水利与环境学院,湖北宜昌443002

出　　处：《水文》2010年第2期36-43,共8页Journal of China Hydrology

基　　金：国家自然科学基金项目(40701024)

摘　　要：在应用瞬时单位线(IUH)进行流域汇流模拟时,需要先率定其2个参数:线性水库的个数n及调蓄系数K。研究表明,用传统的矩法率定得到的IUH,对地面径流的模拟精度较差,需要对参数进行更新。此前袁作新给出了一个用于参数更新的递归公式。本文推导了一个新的递归公式,并与袁作新公式的应用效果进行了对比。新递归方程的推导原理是针对地面径流过程线的2个特征值:洪峰流量和峰现时间,按模拟值与观测值之间的比来调整参数n和K,以使调整后得到的地面径流尽量接近观测值,调整的目标函数选取确定性系数(DC)和误差的均方值(MSE)。将新递归公式和袁作新公式应用于2个案例。结果表明,新递归公式在提高地面径流模拟精度上要优于袁作新公式,对于案例1,新递归公式能提高模拟精度,而袁作新公式则不能;对于案例2,新递归公式提高模拟精度的幅度要高于袁作新公式,DC值提高了1.1%,MSE值降低了14.2%。分析原因认为较大的参数调整幅度可能跨越最优点,而新递归公式对参数的调整幅度小于袁作新公式,从而使其能够找到最优点。应用本文的递归公式时,不宜调整次数过多,否则会降低地面径流模拟精度,对2个案例的最优调整次数均为2次,产生此现象的原因是增加调整次数虽然可以提高对洪峰流量和峰现时间的模拟精度,但不一定能提高对整个地面径流过程的模拟精度。Instantaneous unit hydrograph is the outflow from the instantaneous application of unit net rainfall over the catchment.The IUH is widely used for surface runoff simulation by using net rainfall as input.The IUH consists of 2 parameters,n and K,the determination of which is normally made by using the moment method.It was found in previous researches that the calculated surface runoffs based on the parameters from the moment method did not fit the observed ones well,an updating of the parameters is necessary.Therefore,the aim of this study is to firstly derive a recursive equation for parameter updating of the IUHs,and secondly investigate the appropriate number of updating times for applying the derived equation.As the most important characteristics of the surface runoff hydrographs are the peak discharge（Qp） and the time of the rising limb（of the surface hydrograph） to reach the peak（tp）,the recursive equation was deduced by adjusting the calculated Qp and tp repeatedly so as to try to be equal to the observed Qp and tp.When applying the deduced recursive equation,it was found that the number of updating times should be appropriate,for too many number of updating times will deteriorate the performance of the IUH for simulating the surface runoffs.2 flooding events were used for testing the recursive equation derived in this study.The results show that the appropriate number of updating times for both 2 flooding events are 2.After that number of updating times,the deterministic coefficient（DC） and mean squares error（MSE） between the calculated and observed surface runoffs will no longer be improved.The reason of the existence of this appropriate updating number is that,the updating targets：the Qp and tp,are actually indicating partial characterization of the surface runoffs.A precise convergence of the calculated Qp and tp to observed ones does not necessarily guarantee a monotonic improvement of the simulation for the overall course of the surface runoffs,which is indicated by the DC and th

关 键 词：瞬时单位线 参数更新 递归公式 

分 类 号：P338[天文地球—水文科学]