珠江三角洲河网动力变化敏感因素分析

Analysis on Sensitive Factors of River Network Dynamic Changes in Pearl River Delta

近年,珠江三角洲河网出现一些变化,如河网分流比变化,出海口门段局部水位壅高,部分河网汊道行洪断面明显缩窄,水流不畅,河床冲淤变化等等。以上变化中,哪种变化对整个河网系统影响最大,或者最为敏感?这里借助数学模型作为研究工具,建立珠江三角洲河网一维数学模型,通过模拟计算与分析,得出:思贤滘分流节点对河网的影响最为敏感,具有全局性影响,直接影响河网各水道水流动力分布格局,进一步影响入海口门的分流与动力格局;河网内部局部汊道分流变化也会对部分水道或整个河网分流格局产生影响;局部、小幅度的潮位变化或河床冲淤变化对三角洲河网有影响,但影响有限,较大幅度的潮位变化或较大规模的河床冲淤变化也可能影响到整个河网分流与结构稳定。

In recent years,there have been some changes in river network in the Pearl River Delta,such as the change in the flow ratio of the river network,the water level in the exit of the outlet,the obvious narrowing of the flood section of some river channel branches,the unobstructed flow of the flow,the change of the riverbed and silt,and so on.Which of the above changes is the most sensitive or the most sensitive to the entire river network system?With the help of the mathematical model as a research tool,a one-dimensional mathematical model of the river network in the Pearl River Delta is established.Through the simulation and analysis,it is concluded that the influence of the shunting node on the river network is most sensitive and has a global influence,which directly affects the distribution pattern of water flow in each channel of the river network,and further affects the points of the entrance to the sea.The flow and dynamic pattern of the river network can also affect the distributary pattern of some waterways or the whole river network,and the local,small amplitude change of tidal level or the change of river bed erosion and siltation can affect the delta river network,but the influence is limited.The change of the large tidal level or the large scale of the river bed erosion and siltation may be also possibly affects the distribution of the whole river network and the stability of the structure.