黄河入海泥沙输运及沉积过程的数值模拟

以利津站代表的黄河入海径流和泥沙数据驱动ECOMSED模型,对黄河入海泥沙悬移输运过程的逐月时空变化、输送通量以及海底沉积效应进行了数值模拟实验。分析结果表明,在忽略再悬浮作用条件下,黄河入海泥沙的输运扩散过程具有明显的季节变化规律,且这种变化具有年际相似性。黄河泥沙入渤海后总体朝向辽东湾西侧海岸扩散,而主要沉降区域是黄河口附近,且随着距离的增大,沉积通量迅速降低。模拟沉积速率一般在0.5￣0.1mm/年左右,与实际调查结果非常接近。海底地形等高线向渤海海盆西部、渤海湾南部,以及渤海海峡方向突出,也反映了泥沙通量的输送方向。从黄河入海泥沙悬移扩散过程的季节变化特征及其海底沉积效应来看,渤海海域泥沙悬移输运过程受潮汐动力、余流和和底层流场等因子的制约。除了黄河河口地区以外,各月悬浮泥沙高浓度区基本一致,集中分布在潮流能量最强的海域,潮流水平动能的大小与悬沙浓度大小分布基本一致。泥沙悬移输运方向与模拟获得的渤海三维风驱—潮致Lagrange余流的方向具有明显的相关关系,泥沙扩散的方向和强度明显受余流方向和强度的控制。

Numerical Simulations on Transportation and Deposition of SPM Introduced from the Yellow River to the Bohai Sea

A 3D diagnostic model including a suspended sediment transport module,ECOMSED, driven by the monthly discharge and sediment load of the Yellow River, wasapplied to the Bohai Sea during 1983-1984. The simulations on temporal-spatial variety ofSPM (Suspended Particular Matter) concentration, sediment flux, and deposition rate werecarried out. It could be discerned that, the SPM concentration presented distinctly seasonalvariety, and the variability characteristic was similar in two years. Some of the fine sedimentof the Yellow River extended to the western bank of the Liaodong Bay, but most of thesediment deposited around the estuary of the Yellow River, and the deposition fluxprogressively decreased with the distance to the estuary increasing. The deposition kept at arate of 0.05-0.1 mm/a, which is close to the in situ data. There were two areas of high SPMconcentration in the Bohai Sea, one of which can be attributed to the Yellow River discharge,and another one located at the seas with intensive resuspension power may be due to the tidalcurrent energy. The sediment poured from the Yellow River was transported mainly along thetrack of the Lagrange residual circulations. In one word, the suspended load transport wasbasically attributed to the wind-driven and tidal-forcing Lagrange residual circulations. Theresuspension flux was related to the bottom currents: the larger the current speed, the morethe sediment resuspended.