珠江磨刀门河口径潮动力耦合条件下余水位的多时空尺度分析

Investigation of temporal-spatial distribution patterns of residual water level under the influence of tide-river interaction in the Modaomen Estuary,Zhujiang River

本文通过构建径潮动力耦合条件下潮波传播的一维水动力解析模型,从理论机制上探讨珠江磨刀门河口径潮动力非线性作用下余水位的多时空尺度变化。结果表明:余水位变化呈现明显的大小潮和洪枯季变化,枯季余水位大小潮的变化幅度介于0~0.4m,而洪季余水位与上游径流紧密相关,增幅大枯季一个量级(介于0~6m);解析模型可分离控制余水位变化的3个主要因素,即径流、潮流和径潮相互作用因子,计算结果表明河口不同区段余水位的主控因素有明显的洪枯季变化,上游段,枯季余水位受径潮相互作用因子控制,洪季受径流因子控制;枯季下游段余水位受潮流控制,而洪季余水位主要受径潮相互作用因子控制。

In this study,the temporal-spatial distribution patterns of residual water level under the influence of nonlinear tide-river interaction in the Modaomen Estuary was explored by means of a one-dimensional analytical model for tidal river hydrodynamics.Model results showed that the distribution patterns of residual water level were characterized by an apparent spring-neap cycle and a dry-flood change.In particular,for the dry season,the residual water level was featured by significant spring-neap cycle,with values ranging between 0 and 0.4 m.On the other hand,the magnitude of residual water level in the flood season is one-order larger than that in the dry season（ranging between 0 and 6 m）and is closely related to the freshwater discharge imposed at the upstream end.With analytical model,it is possible to decompose the residual water level into different components,linking to tide,river and tide-river interaction,respectively.It was shown that,during the dry season,the residual water level was mainly controlled by the tidal forcing in the downstream reach of the Modaomen Estuary,while it was impacted by both the tide and river flow in the upstream part.For the flood season,the model results showed that the residual water level was mainly determined by the river flow for the whole estuary.