鄱阳湖流域水沙周期特征及其影响因素

Periodic Properties and Its Implications of the Sediment Load and Runoff Changes of the Poyang Lake Basin

采用交叉小波变换与小波相干方法分析了鄱阳湖流域＂五河＂控制站1955~2005年径流量与输沙量周期特征,结果表明：径流量和输沙量存在2~4 a的周期,径流量周期强烈振荡变化主要发生在20世纪60年代末至70年代中期以及90年代;而输沙量显著周期主要发生在20世纪60年代末至70年代中期.径流量的周期变化主要受降雨量的影响,而输沙量周期变化主要受到径流量的影响,同时还受森林覆盖率和水利工程的影响;20世纪60到70年代森林覆盖率降低,同时期径流量的周期变化显著引起输沙量的强烈震荡;20世纪90年代径流量周期震荡强烈并没有引起输沙量显著的周期变化,这是因为流域内的森林覆盖率提高以及水利工程的修建,而水利工程是输沙量周期变化不显著的最主要原因.

The annual runoff and its suspended sediment loads at five hydrological stations located in the five tributaries of the Poyang Lake basin are analyzed using the continuous wavelet transform,cross wavelet and wavelet coherence techniques.The results indicate that：the runoff and sediment load changes are of 2-4 years periods.The significant wavelet spectrum of runoff fluctuations is observed mainly from 1960s to mid 1970s and 1990s.However,the significant periods of the sediment load are detected mainly in the late 1960s to mid 1970s.Periodicity properties of runoff changes are mainly due to the precipitation variations,and they are also heavily influenced by forestation,deforestation and hydrological regulations of the hydraulic facilities.The forest coverage decreased during 1960s and 1970s,which greatly increased the sediment load and hence the large-magnitude sediment load fluctuations.However,the significant variability of the runoff changes does not trigger significant periodic changes which should be attributed to the increased forest coverage and increasing number of hydraulic facilities within the Poyang Lake basin.In addition,hydrological regulations of the hydraulic facilities should be responsible for the insignificant periodicity of the sediment load changes.