黄土高原暴雨产沙路径及防控——基于无定河流域2017-07-26暴雨认识

Paths and prevention of sediment during storm-runoff on the Loess Plateau:Based on the rainstorm of 2017-07-26 in Wuding River

黄土高原大规模生态建设显著降低黄河输沙量,但暴雨条件下,黄河典型支流输沙量仍然维持在高位。2017年7月26日无定河普降暴雨,白家川站洪峰流量达4 480 m3/s,最大含沙量达837 kg/m3,为1975年建站以来最大洪水。暴雨后,笔者对典型小流域侵蚀输沙特征进行调查,暴雨情况下,小流域土壤侵蚀模数仍然很高,但是由于坝系拦蓄,流域泥沙输移比显著降低。暴雨条件下,黄土高原丘陵沟壑区产沙路径为梯田下部田坎→坡耕地→土质道路→沟壁→淤地坝垮坝→沟道及河道堆土。针对产沙路径,笔者提出新形势下黄土高原土壤侵蚀5条防治对策:1)完善小流域→一级支流→黄河干流三级输沙通道,保障排沙畅通;2)持续推进退耕还林(草)和坡改梯工程,加强坡耕地治理;3)加强农村道路建设和坡面径流调控能力建设,防治道路和沟壁侵蚀;4)加强梯田管护;5)加强生产建设项目监管,管控建设项目弃土。

[Background] The large-scale ecological construction of loess plateau has significantly reduced the amount of sediment transport in the Yellow River,but the amount of sediment transport of some typical tributaries is still high in the rainstorm condition. On July 26,2017,heavy rainstorm hit the Wuding river,the peak discharge reached 4 480 m^3/s,maximum sediment concentration was 837 kg/m^3,which is the maximum recorded value since the construction of Baijiachuan hydrologic station.[Methods] After rainstorm,we carried on an investigation on the erosion and sediment transport characteristics in typical watershed. [Results] Under rainstorm,the soil erosion modulus of the small watershed is still very high, while due to the check dam system, the sediment delivery ratio is significantly reduced. In the background of the large-scale ecological governance,the main path of sediment transport in hilly gully region of Loess Plateau was terraced fields →sloping farmland →road →gully→check dam break→spoil in channel. [Conclusions] In view of the sediment transport path,theauthor puts forward five countermeasures for the prevention and control of the Loess Plateau under the new situation： 1） Improving the small watershed→a tributary→the mainstream of the Yellow River sediment transport channel,to ensure sediment transport fluently; 2） Keep promoting the Grain-for-Green Project and sloping to terrace project to strengthen the management of sloping farmland; 3） To strengthen the construction of rural road and control the capacity of slope runoff,prevention of road and gully erosion;4） To enlargement the management of terraces; 5） To enhance the construction of project supervision,control construction projects spoil.