人工采沙及航道整治对珠江三角洲水流动力条件的影响

本文借助数值计算,运用"三级联合解法"对圣维南方程组进行求解,对1990年和2005年实测地形条件下珠江三角洲动力条件进行复演,研究了在高强度、大范围人工采沙和航道整治等人类活动作用下,三角洲航道网内部水流动力条件的变化。研究结果表明:由于河床的下切,导致同流量水位下降明显,一级分流节点思贤站的百年一遇流量水位下降达2.68m;同时,由于河槽容积增加,航道网内部潮汐动力增强,该站的年均潮差从1990年的0.35m增加到2005年的0.53m。河道断面面积的剧烈变化,引起了航道网内部及口门处水量的重新分配,其中洪奇门和磨刀门流量增加显著,其余6个口门均有不同程度的减少。珠江三角洲航道网内部水流动力条件的变化,亦是近年来珠江三角洲咸灾频发的主要诱因之一。

Impact of sand excavation and waterway regulation on hydrodynamics of Pearl River networks

The established mathematical model for hydrodynamics of Pearl River networks is applied to numerically study the flow under the conditions of the topographic measured in 1990 and 2005 respectively. It is found that the water levels of the hydrological stations in the river networks decrease obviously in this period due to mankind activities including high intensity sand excavation and waterway regulation.The water level at the Sixianjiao Station which is the important control node of the river networks reduces by 2.68m during the flood with the probability of 0.01.Owing to the increase of channel volume the tidal dynamics of the river networks is enhanced,so that the annual tidal difference increases from 0.35m to 0.53m.As a result of the intensive change of river cross section the discharge in the river networks and river mouths is redistributed.The discharge of Hongqi River Mouth and Modao River Mouth increases significantly,but the discharge of other six river mouths decreases.The change of internal hydrodynamics of the river networks also induces the saline intrusion problem happened in the recent years.