黄河上游“十大孔兑”高含沙洪水灾害过程与输沙特性

Routing Process and Sediment Transport of Hyper-concentrated Flow Disasters from the Ten Tributaries in the Upper Yellow River

黄河上游'十大孔兑'沙漠流域的高含沙洪水,是该区域季节交替的风水复合侵蚀作用的结果。以'十大孔兑'流域的典型支沟苏达拉尔沟为依托,基于野外原型观测,系统深入地分析了沙漠粗沙高含沙洪水(泥流)输沙特性与致灾过程。研究结果表明:该区域的高含沙洪水,由暴雨诱发,沿程叠加风力、水力、重力等侵蚀作用产沙,最终演变为高含沙洪水(泥流)灾害。降雨强度大于0. 27 mm/min且持续35~60 min以上的暴雨,大多可诱发高含沙洪水,含沙量可高达1 400 kg/m3以上。研究结果为开展'十大孔兑'沙漠流域风水复合侵蚀模型研究打下了坚实的理论基础;为干旱半干旱区沙漠流域水土流失防控与灾害治理提供了工程参考意见;对从流域侵蚀产沙角度出发,探究黄河河道水沙变化,维护黄河健康而言,亦具有重要的参考价值。

The hyper-concentrated flows from the Ten Tributaries in the Upper Yellow River are recognized as the result of severe and seasonal alternate aeolian-fluvial interactions.Here,based on the typical tributary i.e.,Sudalaer desert channel of the Ten Tributary watershed,the sediment transport process and the mechanism of hyper-concentrated(mud)flow disasters mainly composed of coarse aeolian sands were studied systematically by means of field observation.Our results indicate that the hyper-concentrated flows in the study area are always induced by rainfall,and ultimately develop into mud flow disasters under the coupling erosion effects of aeolian-fluvial interactions and gravitational erosion during the routing processes,with the critical value of rainfall intensity exceeding 0.27 mm/min,rainfall duration about 35~60 min,and sediment concentration exceeding 1 400 kg/m3.These main findings could provide a solid foundation for aeolian-fluvial interaction modeling research and may give some helpful advice on governing and mitigating water and soil erosion,and are even of great guiding significance for water sand sediment variability research as well as maintaining the health of the Yellow River from the perspective of watershed scale.