Studies On The Runoff And Its Influencing Factors In The Upper Reachs Of The Minjiang River

Water Resources system and hydro-environment are vast,variant and nonlinear energy-system. the variance of runoff,which is main factor in the system and dominants the variance of the whole system,has important effects on social economy and environment of water resources of the district,because of the synthetic influence of weather,geography and human-mand development actions,runoff of the theupper reach of the minjiang riverbasin is complicated,multi-time-scale dependent,random,discontinuous,and non-linear etc.This thesis,under the support of Chinese National basic research development planning"973"(NO.2002CB111504),applies modern new theories(wavelet transformation)and traditional methods,to systematically study the variant characteristic of runoffs for the The Upper Reach of the Minjiang River by using the latest hydrological records.based on such analyses,this study forecasts the runoff change trend for the The Upper Reach of the Minjiang River.Principal findings are concluded as follows:Firstly,based on the natural annual runoff time series of hundreds years for the The Upper Reach of the Minjiang Rive basin,variance in multi-time scales of the series are probed with Morlet wavelet transform.Themajor periods of the runoff of the The Upper Reach of the Minjiang Rive are abort 4 years,8 years and 13 years,respectively,These major periods are dominant change trends of The Upper Reach of the Minjiang Rive runoff.Remove the part of the noise monitoring information,and to reveal the Upper Reach of the Minjiang River show lower with Daubechies wavelet transform.Secondly,The spatial analysis of vegetation pattern at a landscape scale shows the dominant vegetation are composed of conifer forests,shrub lands and grasslands.their areas accont for 30%.Analysis indicates that vegetation pattern has complicated relationship with aspect,elevation.The upper reaches deforestation of Maingjiang River presents passive correlation with the change in the runoff,the correlated data(r~2=-0.602).Thirdly,the analysis of meteorological shows runoff is correlated to elevation,radiation,temperature,precipitation and so on.Fourthly,The Upper Reach of the Minjiang Rive being established in the lesast-squares regression model return flow forecast models.Finally,in this study,modern new theories and methods were applied to the The Upper Reach of the Minjiang Rive to analyze and forecast the long-term variant characteristic of its annual runoff and its correlation with influencing factors.