黄河调水调沙期间入海泥沙沉积动力过程的数值模拟

Numerical Simulating on Sediment Transportation in the Estuary and its Adjacent Areas During the Water and Sediment Regulation Period of the Huanghe River

本文根据2007年黄河调水调沙期间黄河三角洲及其毗邻海域的水文、泥沙调查数据资料,使用Mike 3三维水沙数值模型模拟了黄河调水调沙全过程(低流量、高流量、高含沙量)入海水沙输运过程,揭示了人造洪峰下水沙扩散范围和特征,分析了泥沙入海后的沉积动力学机制。研究发现:入海淡水和表层细颗粒泥沙主要以异轻羽状流形式向外海和河口两侧沿岸扩散,中、底层粗颗粒泥沙向外海扩散非常有限,有少量向河口两侧沿岸扩散,扩散范围小于表层;河口区在涨-落、落-涨潮流转换时刻分别存在着潮流切变锋,切变锋均形成在浅水区,而后向深水区移动,切变锋的发生对泥沙向外海扩散有着明显的阻隔作用。

Based on a synthetic survey which was carried out in the Huanghe estuary and its adjacent area during the water-sediment regulation period in the summer season of 2007, the MIKE 3 numerical model was applied to the Huanghe estuary and its adjacent areas. With the model, the transportation processes of the fresh water and suspended sediment were successfully simulated in the Huanghe estuar- y, and their dispersal patterns in different discharge phase （Low-flow, high-flow, high sediment concen- tration） were analyzed carefully. The results of numerical model showed that whether the river dis- charge was low or high, the fresh water could disperse in the surface layer as the hypopycnal flow. When the river discharge was low, river-delivered suspended sediment dispersed towards the offshore was mainly through the hypopycnal flow~ When the river discharge was high, the hypopycnal flow was also an important controlling factor for the dispersal of fine sediment, most of the coarse sediment de- posited in the nearshore area of the Huanghe estuary, a small amount of coarse sediment was transpor- ted along the coastline. Two types of shear front were identified in the offshore region near the river mouth at the conversion time of tidal flow, which was formed in the shallow water, and then moved to the deep water. Sediment was transported along the coast, the offshore transportation was significant constrained.