372 / 2024-02-29 22:42:47

The effect of multi-factors on water exchange in the Bohai Sea

Bohai Sea,water exchange,wave,water age

Subtheme 3: Eco-hydraulics and Environment > Topic 2: Water Eco-environment Monitoring and Simulation

    Bohai Sea is a typical semi-enclosed shallow sea, because of the developed economy and large population, it is under great environmental pressure. In order to protect and improve the water environment in the Bohai Sea, the characteristics and mechanism of water exchange have received extensive attention and continuous research. The effects of different factors such as tide, wind and wave on water exchange in the Bohai Sea have been studied, but the comprehensive understanding of the contribution and mechanism of multi-factors to water exchange in the Bohai Sea are insufficient. Considering the influence of tide, wind and wave, a coupled hydrodynamic model of the Bohai Sea was constructed in this study, and the water age model was set up on this basis. The spatial distribution of residual current and water age were obtained from the simulation results. Based on the topography and wind statistical characteristics of the Bohai Sea, the influence of wave on water exchange was analyzed, especially during the storm surge. The results show that: 1) Combing the influence of tide, wind and waves, the trend of residual current in the central basin of the Bohai Sea is anticlockwise and there are several small-scale vortexes in other three bays. The overall circulation characteristics of the Bohai Sea with and without wave driving force have little difference. 2) Under the influence of tide, wind and waves, the water age in the Bohai Sea is concentrated in the Bohai Bay and the top of the Liaodong Bay, while in the Laizhou Bay and the central of the Bohai Sea is relatively small. The effect of waves on water exchange in the Bohai Sea are restricted to local region. 3) Through the analysis of wind speed, wind fetch and topography conditions, the mechanism of waves on water exchange in the Bohai Sea is revealed. High wind speed and long wind fetch will lead to wave accumulation, while the influence of topography is complicated. In the offshore area with deep water depth, waves have no significant effect on water exchange, but in the nearshore area, the impact of waves is obvious due to wave breaking caused by the shallower topography.