嫩江江桥站水沙变化特征及驱动因素分析

Runoff and Sediment Dynamics and Driving Factors in Jiangqiao Hydrological Station of Nunkiang River

采用线性关系外推法、小波分析和Mann—Kendall检验法对嫩江江桥站控制区1955—2006年期间年降水、径流和输沙序列变化特征进行了分析。结果表明,受人类活动影响之前,输沙序列震荡不明显,输沙和降水量不具相关性,受人类活动影响之后,输沙序列出现震荡特征,输沙和降水量之间的相关性达显著水平。采用线性关系外推法计算了人类活动和降水对径流、输沙量的影响,与基准期相比,研究区年均径流量减少了7.900×109 m3,其中,降水减少占4.130×109 m3,人类活动影响占3.770×109 m3;同时,受降水影响减沙3.329×105 t,受人类活动影响增沙3.899×105 t,年均总输沙量增加了5.700×104 t。总之,人类活动是研究区径流减少量和输沙量增多的重要驱动因素。

Linear regression method,wavelet analysis and sequential Mann—Kendall test analysis were applied to characterize runoff and sediment time series collected at Jiangqiao hydrological station of Nunkiang River from 1955—2006.The results show that during 1955—1966,a period with little human activities,sediment yields remained relatively stable and no correlation between sediment and rainfall was found significant.In contrast,strong sediment fluctuations and a close correlation between sediment and rainfall were identified in 1967—2006,mainly owing to reinforced human disturbances.Linear regression method was adopted quantify the effects of rainfall and human activity on runoff and sediment.Comparing with base period,total runoff volume of the research area reduced by 7.90×109 m3 per year,within which 3.770×109 m3,4.130×109 m3 were affected by human activity and rainfall,respectively.During 1967—2006,the sediment reduced at a rate of 3.329×105 t per year given the decreased rainfall;however,human activity resulted in a sediment increase of 3.899×105 t per year.In summary,human disturbance,rather than rainfall variations,was the driving factor for the decline of runoff and the increment of sediment in the research area during the study period.