黄河口海洋动力输沙能力分析

Analysis on sediment transporting capacity by sea power in the Yellow River Estuary

采用数学模型和资料分析的方法对清水沟时期黄河入海泥沙的输移扩散规律进行了分析研究。通过数模计算得出:随着河口三角洲的演变,河口海洋动力输沙能力也相应变化,河口沙嘴突出岸线的程度越大,海洋输沙能力越大,输入外海的泥沙越多;对于特定的岸边界,海洋输沙能力的变化取决于入海水沙搭配关系,在入海沙量相同条件下,来沙系数越小,输送至外海沙量越多,反之亦然。通过实测资料分析指出:黄河口海洋输沙十分复杂,涉及岸边界、各种持续和偶发的动力等诸多因素。实测的冲淤分布往往是诸多因素综合作用的结果,很难分离出某种因素单独所起的作用。实测数据显示,河口泥沙冲淤分布与来水来沙条件相关性不强。但总的看来,黄河改道清水沟以来,1977-2000年间,来沙量偏少,输入外海泥沙的比例比其它流路时期偏大,排沙比达54%,平均每年输入外海泥沙的绝对量为2.83亿t。但具体到各个年份,不论是排沙比还是绝对量,年际间差异都很大,每年输入外海的沙量并不局限在2-3亿t。

The law of sediment transport in the period of Qingshuigou channel of the Yellow River Mouth has been studied by using the mathematical model and analysis of field data in this paper. The knowledge based on calculated results is as follows： the sediment transporting capacity changes with the evolution of the Yellow River Delta; the more the sand spit of river mouth protrudes out of coastline, the more the sediment load is transported into deep sea; the sediment transporting capacity depends on the relation of the water-sediment ratio for a specified coastline. For the same sediment amount in the incoming flow, the smaller the ratio of sediment concentration to the flow discharge, the more sediment load will be transported into the deep sea, and the reverse is also true. The analysis of the field data indicates that the factors affecting the sediment transport in the Yellow River Mouth are very complicated, including coastline boundaries, various continuous and accidental powers, and so on. The measured distribution of erosion and deposition in the estuary are often resulted from various facts. It is difficult to identify the role of one certain factor from the others. The field data show that the distribution is less related to the incoming water and sediment. In general, the incoming sediment amounts during the period of Qingshuigou channel （1977 - 2000） are comparatively low, but he proportion of transported sediment into the deep sea is greater than ones during other periods. The percentage of the sediment load transported into the deep sea to the incoming sediment amount is 54%, the average annual sediment amount transported into the deep sea is 283 million tons. However, whether the percentage or the sediment amount in different years may have a big difference.