Variation Trends Of Runoffs In The Middle Yellow River And Its Response To Climate Change

Because of global warming,precipitation distribution and human irrational development and utilization of water resources,making the middle reaches of the Yellow River Runoff great changes have taken place,has caused a series of restricting human survival,ecological environment sustainable development.Therefore,it is significant to analyze the trend of runoff change to realize the sustainable development and utilization of water resources.According to the trunk stream of the middle reache of the Yellow River Hydrological control stations(Tou Dao Guai,Long Men,San Men Xia and Hua Yuan Kou)from 1952 to 2008 annual natural runoff data,combined with San Men Xia-Hua Yuan Kou section 18 meteorological station from 1961 to 2011 years of meteorological data,by using the method of linear tendency estimate,Kendall rank correlation test,R/S analysis,Mann-Kendall nonparametric slide a rank correlation test,T test,the cumulative departure method and Morlet wavelet analysis,the trend analysis of natural runoff in the middle reaches of the Yellow River,mutation point and the main cycle analysis,analysis of the runoff variation trend in the middle reaches of the Yellow River and its response to climate change.The main research achievements are as follows:The middle reaches of the Yellow River hydrological station control natural runoff has obvious decreasing trend,Hua Yuan Kou runoff decreasing trend is most obvious,the average annual linear decline rate of about-4.225 billion m3,the four sites similar trend overall trends,have peaked around 1964 runoff,runoff to the minimum in 2002;According to Kendall rank correlation coefficient,| Z | values in excess of 2.32 indicate runoff decline more intense;Observe the Hurst index,are within the range of 0.7-0.85,show the trend of the future,will continue to downward trend.Mutations in the time of the four main hydrological station is generally showed consistency,turn head of natural runoff mutation time occurred in 1974 and 1974,Long Men,San Men Xia and Hua Yuan Kou mutation of natural runoff time took placein 1974 and 1991.The change trend between main hydrological sites in the middle reaches of the Yellow River has roughly 5 a,11 a,22 a three main oscillation period.In San Men Xia-Hua Yuan Kou interval,nearly 51 years of study period,qualitatively analyzes the climate elements in rainfall and temperature effects on runoff.