黄河三角洲孤东近岸海床冲刷平衡深度预判

Prediction of Seabed Scouring Equilibrium Depth in Gudong Coast of the Yellow River Delta

近年来,在流域来水来沙减少和河口尾闾不断改道变迁的情势下,黄河三角洲除现行河口口门附近外,其他区域都表现出不同程度的侵蚀。孤东海岸是黄河三角洲侵蚀最强烈的区域,海床冲刷演变过程与冲刷动力机制被广泛关注,但其冲刷平衡深度及冲刷极限深度却一直没有定论。基于尖点突变理论,针对近岸泥沙运动特征,推导出海床冲刷平衡深度预判公式;通过预判公式计算得到孤东近海海床冲刷平衡深度为6.5~7.5 m,与海岸剖面演变过程分析得到的冲刷极限深度6.8~7.2 m一致,证明了泥沙突变模型在预测海床冲刷中的适用性。预判结果表明:孤东海岸堤前海床还将持续冲刷2 m左右,加强海堤防护工程日常维护十分必要。

In recent years,with the decrease of water and sediment in the basin and the continuous diversion and change of the estuary tail,the Yellow River delta has shown different degrees of erosion in other areas except the current estuary entrance.Gudong coast is the area with the strongest erosion in the Yellow River delta.The evolution process and dynamic mechanism of seabed erosion have been widely concerned,but its scouring equilibrium depth and scouring limit have not been determined.Based on the cusp catastrophe theory,according to the char⁃acteristics of nearshore sediment movement,the sediment incipient model under the joint action of wave current and sediment was estab⁃lished,and the prediction formula of seabed scouring equilibrium depth was derived.Through the prediction formula calculation,the equilib⁃rium depth of seabed scouring in Gudong offshore was between 6.5-7.5 m,which was consistent with the scouring limit depth of 6.8-7.2 m obtained from the analysis of coastal profile evolution process,which proved the applicability of sediment catastrophe model in predicting sea⁃bed scouring.The prediction results show that the seabed in front of the breakwater of Gudong coast will continue to scour for about 2 m,so it is very necessary to strengthen the daily maintenance of the breakwater protection project.