Study On The Runoff Change Characteristic And Forecast Method Of The Yellow River

Water resource is one of the essential elements supporting human survival and sustainable economic growth,as an important source of water resources,rivers runoff dominates the change of water resources system.Due to the basin climate,natural geography,social development and comprehensive effects of human activity,its change present a nonlinear and non-stationary dynamic system.This paper uses on 73 year and 876 months of hydrological data of three representative stations in the middle and lower reaches of the Yellow River basin.The characteristics and regularity of the evolution of Yellow River runoff are analyzed on the basis of predecessors' research analysis.And to predict future changes in the Yellow River runoff by building the forecast model,these provide important basis for the Yellow River basin water resources optimal allocation and rational development and utilization.The paper main research content and achievements are as follows:(1)Through the analysis of basic statistical characteristics,annual distribution characteristics and the general characteristics of interannual changes of the Yellow River basin runoff,it is concluded that annual runoff distribution were positively,volume of runoff distribution is uneven within the year,the interannual change is larger.There are large variations of runoff within the year,annual runoff time series of the Yellow River in the 1980 s had a weak trend of increase,and later it began to present obvious downward trend.(2)Mann-Kendall Rank correlation test and Spearman Rank correlation test are adopted to analysis the tendency of annual runoff series at the three representative standing of the middle and lower reaches in the Yellow River.The results show that it presents a trend of fluctuations up and down overall.(3)The periodic analysis of runoff in the Yellow River basin is analyzed by wavelet analysis theory.The results show that the characteristics of the multitemporal scale of river flow in the middle and lower reaches of the Yellow River,the larger scale of the periodic change is nested in a smaller scale cycle,the periodic changes of 10-30 and 7-16 years have the same performance,the cycle performance of the smaller scale of 10 years has a slight difference in the middle and lower reaches 3 stations;the first major cycle of the middle and lower reaches of the Yellow River basin is 32 years.It shows that the river flow changes in the middle and lower reaches of the Yellow River are synchronicity.3 stations have different minor cycle,which has 22 a Minor Cycle,but in the role of the basin,such as 22 a cycle changes upstream and downstream of the Yellow River runoff changes more than in the middle reaches of the Yellow River to the influence of impact.(4)The transmutation of the annual runoff sequence in the Yellow River basin was analyzed by the Mann-Kendall mutation detection method and sliding T test method.The results show that the most obvious mutation points of the annual runoff in the Yellow River basin occurred in 1934,1936,1941 and 1965.(5)Based on wavelet analysis and artificial neural network prediction model(WANN)are adopted to forecast annual,monthly runoff flow of the Yellow River basin.The results show that the constructed WANN model is effective in the data prediction,and it can meet the practical requirements,which can be used in the forecast of the annual and monthly runoff flow of the Yellow River basin.(6)The natural flow data of the three stations in the Yellow River basin is predicted by the three-step Volterra adaptive filter prediction model.The prediction results show that the model can be used in the forecast of the annual and monthly runoff flow of the Yellow River basin.In comparison with the predicted results of WANN forecast model in the fifth chapter constructs,three-step Volterra adaptive filter prediction model in annual,monthly runoff flow of the Yellow River basin has better approximation ability,alignment is higher,relatively good prediction effect.