Study On Variation Characteristics Of Runoff And Sediment And Their Quantitative Relationship With Influence Factors In Changting Section Of Tingjiang River Basin

Study on the change of runoff and sediment is not only an important field but also research focus in hydrology.Research on the variation characteristics of runoff and sediment as well as their influence factors is significant for soil erosion control.Nowadays,the study of variation of runoff and sediment is concentrated on big rivers in north or central regions mainly,and is few in southern part which has abundant rainfall.Meanwhile,the main influence factors of the variation of runoff and sediment are the precipitation factor and human activities factor,and other complex factors are seldom involved.Changting section of Tingjiang River basin was chosen as the study area of this paper,and hydrological monitoring data,meteorological data,remote sensing data,and humanistic data were used to study on the variation of runoff and sediment and their quantitative relationship with influence factors were performed.The main contents and results of this paper are as follows:(1)Analysis of variation characteristics of runoff and sediment.The runoff data of Changting section of Tingjiang River basin at two hydrological stations(Guanyin bridge&Shanghang)from 1982 to 2014 as well as sediment rate time series data were used.The cumulative anomaly method was used to analyze the variation trend about runoff and sediment of Changting section of Tingjiang River basin over the past 30 years.The wavelet transform method was used to analyze the variation trend monthly and annually of sediment as well as periodic characters.The runoff and sediment of Changting section of Tingjiang River basin distributed unequally annually,runoff and sediment are mainly concentrated in 3-6 months;there is a sudden change of the runoff and sediment in 1991 and 2000;the trend of runoff and sediment at each station shows the same trend,the runoff of Guanyin bridge increased firstly,then decreased,while the runoff of Shanghang increased slowly and then decreased fast.The runoff and sediment of series show multi-scale periodicity,the first main cycle of the two hydrological satstion annual runoff sequence is 25 years,The first main cycle of the two hydrological satstion annual sediment sequence is 24 years,The first main cycle of the two hydrological satstion monthly sediment sequence is 18 months.The main cycle of the monthly runoff sequence between Guanyin bridge and Shanghang is different,Guanyin bridge'sfirst main cycle is 44 months,Shanghang's first main cycle is 18 months.(2)Correlation analysis of runoff and sediment change.The climatic factors and human activities factors have been chosen as the independent variables and various factors of runoff and sediment change have been chosen as dependent variables.Pearson correlation analysis was used to filter suitable independent variables and dependent variables for proving the influence of runoff and sediment changes.The rainfall and runoff and sediment shows strongest correlation while vegetation cover and governance fund taking second place.Temperature and evaporation has week correlation with runoff and sediment.Runoff difference and sediment difference have shown the correlation between runoff and sediment change and natural factors as well as human activity better.(3)Quantitative study on influencing factors of runoff and sediment change.The cumulative slope change rate comparison method and the multiple linear ridge regression method were respectively used to quantitatively calculate and analyze the contribution rates of each factor to runoff and sediment change.The results of multiple linear regression method were more reasonable.During 1982-2013,rainfall factor has its maximum effect of all the influence factors in Changting section of Tingjiang River basin,with the contribution rate of more than 50%while the temperature has its minimum effect with the contribution rate of less than 10%.The proportion of vegetation cover and government funds is about 10%?15%,and the vegetation cover and government funds and other human activities should be greater than the runoff on the effect of sediment.