潮波运动对珠江三角洲分流的影响

感潮河段内节点分流受潮波作用的影响,其分流过程与非感潮河段节点有所不同。本文以河网密布且潮波作用强烈的珠江三角洲为研究对象,利用二维水动力模型在“无径”、“无潮”和“径潮”三种条件下进行模拟,引入分流不均匀系数定量描述流量分配,量化了潮波对感潮河段节点处分流的影响。结果表明,潮波改变了珠江三角洲区域径流在河道分支内的分配,特别是在枯季。整体而言潮波的作用是抑制无潮情况下的不均匀分流,枯季时西江下游节点处潮波作用可以逆转径流单独作用时的影响。敏感性分析表明,对节点处分流影响最大的是M2分潮,其次是K1,O1和S2。另外,长期密集采砂造成的水深增加进一步加强了潮波作用的影响。

Tidal impacts on the flow division at the bifurcation in the Pearl River Delta

The discharge distribution is influenced by the tidal behavior at tidally affected junctions. A 2D hydrodynamic model covering the entire PRD has been established and applied to quantify the tidal influence on subtidal flow division at the tidal junctions. The discharge asymmetry index is introduced to quantify the subtidal discharge division. The results show that the tidal wave changes the allocation of river discharge in distributary branches, especially in dry season. Generally, the effect of tidal wave is to restrain the uneven diversion without tides. In dry season, the effect of tidal wave at junctions in the lower reaches of Xijiang river can reverse the effect induced by river discharge only. Sensitivity analysis shows that tide component M2 makes the largest contribution on flow division at junctions, followed by K1, O1 and S2. In addition, the effect of tidal wave is further strengthened by the increase of water depth caused by long-term and extensive sand excavations.