2007-2017年府谷-龙门段河道冲淤特征及其动力机制

目的]河道演变是水流、泥沙与河床边界相互作用的结果，对水利工程的安全、洪涝灾害的防控有显著的影响。黄河中游府谷—龙门段位于晋陕峡谷地带，以黄土高原沟壑侵蚀地貌为主，流经的黄土高原地区是黄河泥沙的主要来源，因此研究该河段的河道冲淤特征及影响因素对控制黄河中游水土流失有重要意义。方法]基于府谷、吴堡、龙门3个典型水文站径流泥沙及河道断面数据，分析了2007—2017年府谷—龙门段河道冲淤特征及相关影响因素。结果](1)近11年来府谷—龙门段河道整体表现为冲刷，其中府谷—吴堡段表现为河道冲刷量逐渐减小，吴堡—龙门段表现为河道冲刷逐年加剧。(2)府谷—吴堡段呈水减沙增的趋势，吴堡—龙门段整体表现为水多沙少，两河段河道冲淤量与水流含沙量变化同步。(3)府谷—吴堡段悬移质泥沙中值粒径呈增加趋势，河道冲刷变缓；吴堡—龙门段悬移质泥沙中值粒径呈减小趋势，加剧河道侵蚀。(4)府谷站入黄泥沙量增加，河道侵蚀力降低，河道冲刷变缓；吴堡站入黄泥沙量减少，河道侵蚀力增强，河道处于冲刷的状态。结论]径流泥沙的变化在很大程度上影响了府谷—龙门段河道冲淤。在生态环境有所改善的背景下，研究该河段河道冲淤特征及动...

Characteristics and Dynamic Mechanism of River Channel Souring and Silting in the Fugu-Longmen Section During 2007-2017

Objective]River evolution is the result of the interaction between river flow and riverbed boundaries, and has a significant impact on the safety of water projects and the prevention and control of flooding. The Fugu-Longmen section of the middle reaches of the Yellow River is located in the Jin-Shan canyon, and is dominated by gully erosion landform of the Loess Plateau. Riverbank erosion is the main source of sediment in this area. So it is important to study the characteristics and influencing factors of river channel souring and silting in this section to control soil erosion in the middle reaches of the Yellow River. Methods] Based on data of runoff, sediment and river cross-section in three typical hydrological stations, Fugu, Wubu and Longmen, the characteristics of channel erosion and siltation, and the related influencing factors in Fugu-Longmen section from 2007 to 2017 were analysed. Results](1)The channel exhibited erosion in Fugu-Longmen section in the past 11 years, with the channel in Fugu-Wubu section exhibiting a gradual decrease and the channel exhibiting an increase in Wubu-Longmen section.(2)The Fugu-Wubu section showed a trend of decreasing water and increasing sediment, while the Wubu-Longmen section showed an overall trend of more water and less sediment. The amount of channel erosion and siltation in the two sections was synchronized with the change of sediment content in the water flow.(3)The median size of suspended sediment in the Fugu-Wubu section increased, then river scour became slower. The median size of suspended sediment in the Wubu-Longmen section tended to decrease, exacerbating river erosion.(4)The amount of incoming yellow sediment in the Fugu-Wubu section increased, the erosive force of the river weakened, and river scouring became slower. The Wubao-Longmen section was in a state of scouring due to human intervention, which reduced the amount of sediment entering the Yellow River and increased the erosive force of the river. These results are consistent with the pattern of channel evolution in both river sections. Conclusion] The change of runoff and sediment have greatly affected the siltation of the Fugu-Longmen section. Under the background of improved ecological environment, it is significance to study the characteristics and dynamic mechanism of river channel dredging in this section of the river to further reduce soil erosion in the middle reaches of the river and prevent flood disasters in the middle and lower reaches of the river.