云南蒋家沟黏性泥石流输沙的涨落特征

间歇性阵流是山区小流域发生的黏性泥石流活动的基本形式,其输沙特性表现出一定的间歇性和涨落特性,其涨落可达均值的2~4个数量级。利用Hurst指数分析了蒋家沟近50年的数千阵泥石流观测资料,发现间歇性阵流的流量、径流量、输沙量序列的Hurst指数均大于0.5,说明序列具有一定程度的长程关联性。同时,对比阵流序列与洪峰序列,发现泥石流阵流的长程关联性强于洪峰序列。另一方面,输沙量的累积百分比均满足统一的指数分布形式:P(S)=CS~(-μ)exp(-S/S_c),其中μ越大意味着序列中输沙量较小的阵次越多;S_c表示的是阵流输沙的涨落情况,即S_c越大,阵流输沙的涨落越大。

Fluctuation of sediment transport by viscous debris flow in Jiangjia Gully

Viscous debris flows usually move by a series of surges in mountain watershed,which transport sediment with temporal intermittency and magnitude fluctuation.In Jiangjia debris-flow gully in Yunnan Province,the discharge of surge fluctuates as high as up to four orders of magnitude within an event of debris flow.The Hurst exponents are used to analyze magnitude fluctuation and size-frequency distribution of sediment discharge data in recent 50 years from Jiangjia Gully.Result shows that the Hurst exponents are much bigger than 0.5,indicating that intermittent surge sequences have long-range correlation.The autocorrelation of intermittent surges is stronger than annual flow peak series.In addition,a distribution can be used to show the accumulated sediment discharge.