The Analysis Of Applicability Of The SIMHYD Model In Songhua River Basin

Rainfall-runoff process is a highly complex hydrological process.Because of uneven spatiotemporal distribution of rainfall and difference of underlying surface characteristics of the basin,simulation of rainfall-runoff process is very difficult.Floods always occurred in 6~ 9 months in the Songhua River basin,in recent years,the impact of climate change and human activities increased the difficulty of accurate forecast of hydrological processes,therefore,to provide scientific guidances in flood control and water resources planning in Songhua River basin,to explore reasonable runoff forecasting methods is quite important.Before simulation of hydrological process,the climatic characteristics and evolution rules of the basin should be cleared.The results show that rainfall and runoff during a year are mainly concentrated in the flood season(June ~ September),and the fluctuation of precipitation in flood seasons during the inter-annual is small,while runoff's is larger.The results of Mann-kendall Non-parametric Test,Sliding Average Method and Sen Slope Estimation Method show that the downtrend of precipitation of flood season in the study area is not significant.The downtrend of runoff in the catchment area of Shi Huiyao is significant while Baishan's is not,and the Correlation Curve Method and Pettitt Mutation Point Test Method are used to identify catastrophe point,and the point of abrupt change is around 1973.Based on the trend analysis and catastrophe point recognition,data of Shi Huiyao in 1955 ~ 2005 a and Baishan in 1958~2010a are divided in several time periods,the parameters for each period respectively use the SIMHYD model to calibration,results show that the model in Nenjiang upstream(natural period)during the four time periods(1960 ~ 1972 a,1960 ~ 1984 a,1985 ~ 1994 a,1985 ~ 1984a)where efficiency coefficient less than 0.5,total runoff relative error more than 10% in validation periods,the simulation precision are poor,SIMHYD model does not apply suitably;the three time periods of Baishan are 1971 ~ 1985 a,1986 ~ 1996 a,1986 ~ 1985 a,where the total runoff relative error less than 5%,and in verification of 1971 ~ 1985 a,efficiency coefficient is 0.756,simulation precision is good,the efficiency coefficient is 0.474 from 1986 a to 1996 a,the simulation accuracy is a bit poor,efficiency coefficient is 0.690 from 1997 a to 2010 a has good simulation precision,the applicability of the model applied in the second Songhua River upstream is nice,it can provide guides for exploitation and management water resources.As for Simulation of the model in the peaks,this paper select simulation effects of different times runoff processes during three validation periods in Baishan basin,the results show simulation values usually less than observed values when runoff depths more than 6mm,main reason lies in the model dose not considering the inhomogeneity of hydrological factors and underlying surface conditions;when the runoff depths less than 6 mm that qualified rates are 85.7%,62.5%,60.0% respectively during three periods,according to Standard for hydrological information and hydrological forecasting,they are grade a,c,c,the results are referable when qualified rate reached grade c,therefore,SIMHYD model can be used to provide references for runoff process forecast of the second Songhua River upstream,but there is a shortage in the simulation of big flood peaks.