黄土丘陵沟壑区岔巴沟下游泥沙传输 时间尺度动态研究

泥沙动态研究目前仍然不够完善, 尤其是在黄土丘陵沟壑区, 有关泥沙传输时间动态的 研究论文还不多见。本文利用岔巴沟下游长达8 年的水沙资料, 探讨了该区不同时间尺度( 洪水 内、月和季节及年际尺度) 上泥沙传输动态。结果表明, 在洪水内时间尺度上, 洪峰超前于沙峰的 事件占洪水事件总数的63.2%, 洪峰和沙峰同时发生及洪峰落后于沙峰的洪水事件则各占 18.4%左右。受高含沙水流的影响, 洪水事件产流量- 含沙量呈现逆时针滞后环, 而与洪峰和沙峰 出现的先后顺序无关。在月和季节尺度上, 存在着可蚀物质“储备- 释放”的过程, 即在晚秋(10 和 11 月份)、冬季和春季可蚀物质是一个积聚过程, 在夏季和早秋( 9 月份) 是泥沙输出流域的释放 过程。在年际尺度上, 含沙量和产沙量年际变化大, 主要与年内发生的洪水事件次数和幅度有关。

Resear ch on the Dynamics of Tempor al Sediment Tr anspor t in a Gullied Loess Basin: the Lower Chabagou Cr eek on the Loess Plateau

Suspended sediment dynamics are still imperfectly understood,especially in loess hilly region on the Loess Plateau with strong temporal variability,where few studies heretofore have been conducted.Using the dataset up to eight-year long in the Lower Chabagou Creek,the variability in suspended sediment load at different temporal scales(within-flood variability,monthly-seasonal and annual) were analyzed in this paper.The results show that,within-flood scale,most of the sediment peaks lag behind peak discharges independent of the occurring sequences of the peaks of sediment and discharge,all the events could present anti-clockwise hysteresis loop resulting from the influence of hyperconcentrated flows on suspended sediment concentration.At monthly and seasonal scales,there is a "store-release " process,i.e.sediment is prepared in winter,spring and late autumn,and exported out in summer and early autumn.At the annual scale,the high-variability in concentration and sediment yield are highly correlated with water yield,resulting from the number and magnitude of floods recorded yearly,since almost all the suspended load is transported during these events.