Study on Characteristics of the Water Diversion Ratio and Impact of the Diversion Dyke at South and North Ports of the Minjiang River During Wet Season

The hydrodynamic processes in estuarine regions play a crucial role in the morphological and ecological stability of coastal zones. As a key hydrodynamic characteristic of bifurcated rivers, the water diversion ratio (WDR) influences flow distribution, sediment transport, and shoreline changes in estuaries. This study focuses on the lower Minjiang River and employs a MIKE 21-based two-dimensional hydrodynamic model to quantify the WDR variations between the South and North Ports on the scale of a tidal cycle during the wet season and to reveal the regulatory effects of diversion dyke length and angle. The results indicate that the WDR of the North Port exhibits significant variation with tidal stages. The WDR of the North Port increases with the length of the diversion dyke. The current 110 m-long dyke has little effect on regulating water flow between the North and South Ports, and its WDR remains unaffected by changes in angle. In contrast, a 450 m-long dyke is highly sensitive to angle variations. This study not only provides scientific support for channel regulation in the lower Minjiang River but also offers indirect insights into shoreline stability and ecological management under the combined influence of human activities and natural processes in estuarine environments.