Variation Characteristics Of Hydrometeorology Elements And Influencing Of Runoff In Karst Basin Under Changing Environment

Under the background of climate change and human activities,the temporal and spatial distribution of river runoff in China has changed significantly.In order to understand deeply the characteristics of runoff changes and its influencing factors can more rationally develop and utilize water resources,and at the same time provide certain theoretical guidance for relevant water conservancy departments.This paper takes" Variation characteristics of hydro-meteorology elements and influencing of runoff in the Karst Basin under changing"as title to carry out research.The main contents and results are as follows:(1)The evolution characteristics of hydro-meteorological elements in the Chengbi river Basin were studied by comprehensive trend analysis,comprehensive variation diagnosis and Morlet wavelet analysis and other methods.The results show that the precipitation and runoff have no significant downward trend in the past 55 years,and the rainfall has not mutation,the runoff has mutated in 1998 and 2014,the first main periods are 6a and 20a.The temperature,potential evapotranspiration and evaporation all have a significant upward trend,and have mutated in 1985,1993 and 1985,the first main periods are 20a,5a and 20a.The calculation results of Hurst exponent show that the meteorological factors will increase in the future,while the runoff will continue to decrease.(2)The annual distribution characteristics of runoff were analyzed by using the annual distribution ratio,concentration period,Gini coefficient and other methods in the Chengbi River Basin.The results show that the annual distribution of runoff is"asymmetrical single peak type".Runoff in summer and autumn accounts for 85%of the annual runoff,and runoff in flood season accounts for 90%of the annual runoff.The main reason for the uneven distribution of runoff in a year is the larger runoff in individual months.According to the trend analysis results of various characteristic indicators,the uneven distribution of runoff is getting lower and lower with the time goes on in the Chengbi River Basin,and gradually changes from uneven to relatively uniform.(3)The decomposition results of sunspot,ENSO events,oscillation index and monsoon index based on ESMD and HHT methods show that,there are multi-time scales and trends of climate factors,which are similar to the period of runoff in the Chengbi River Basin.The calculation results of cross-wavelet show that there are some positive correlation oscillation periods between runoff and climate factors.The results of correlation analysis show that there is a significant correlation between runoff and climatic factors in different degrees.These climatic factors can influence the runoff change in the Chengbi River Basin.(4)Budyko hydro-thermal Coupling model,SCRCQ and elastic coefficient method were used to quantitatively analyze the contribution rate of climate change and human activities to runoff change.The results show that the contribution rates of climate change and human activities to runoff change based by Budyko hydro-thermal coupling model are 46.33%and 53.67%.the contribution rates of climate change and human activities to runoff change based by SCRCQ method are 40.43%and 59.57%.the contribution rates of climate change and human activities to runoff change based on elastic coefficient method are 44%and 56%.The results of the three methods show that the contribution rate of human activities to runoff change is greater than that of climate change in the Chengbi River Basin.