Numerical Simulation Of Hydrodynamics Of Liaohe Estuary Under The Conditions Of Runoff And Tide

Located in the transfer zone between the sea and the land,the offshore and the estuary area are the belt of urban key construction,population gathering,as well as speedy industrial and economic development.The growing population base,the influx of large amounts of pollutants,and the impact of various aspects have led to the ecological environmental deterioration of this region.The change of natural environment and the influence of human activities have facilitated significant variations in the hydrodynamic conditions in the offshore and estuary area.This change also has a crucial impact on the advancement and preservation of the offshore biodiversity.Therefore,it is of great significance to conduct the two-dimensional simulation study on hydrodynamics of the offshore and estuary area.Firstly,based on the Danish hydrodynamic software MIKE21 and the collected offshore terrain and hydrology data,and combined with the on-site measured water level and tidal currents data,the hydrodynamic characteristics of the Beidaihe sea area of the Bohai Sea were simulated,the calculation results turned out to be well consistent with the measured values,and the ebb and flow tidal currents field features of the research sea area were also analyzed in detail.Secondly,based on the data on on-site measured water level,tidal currents and water depth,the numerical simulation study on Liaohe estuary in Liaodong Bay was conducted.MIKE21 HD model was adopted to simulate the changing process of water level and tidal currents,with the impact of the estuarine shoal on the ebb and flow tidal currents field of Liaohe estuary analyzed.The results showed that MIKE21 HD model could accurately simulate the water level and tidal currents process of the research area,and the water depth of tidal flat,with simulation error within the allowable range.The estuarine shoal divides the ebb and flow tidal currents into three flows,the major tidal inlet lying in the northeast of Gaizhou shoal.Wind stress and upstream river runoff are important contributors to estuarine hydrodynamics variation.Based on the impact of wind stress and runoff on tidal currents,numerical simulations were done to the Liaohe Estuary and tidal flat with the MIKE21 model.The simulation results showed that under the influence of wind the hydrodynamic characteristics of the tidal flat area change obviously,and the influence of wind on hydrodynamic conditions was closely related to wind direction.Since the selected measuring sites in this experiment are located in the scenic area of Red Beach National Scenic Corridor,far from the estuary,all of the sites are hardly affected by runoff.In the simulation study on water retention time,it was found that Xuanyan Corridor had the longest water retention time,followed by Taxia Manbu site,and Langqiao Aimeng site had the shortest water retention time,shorter than Qingrendao site.The research results show remarkable guiding significance for the analysis on the degradation of Suaeda salsa vegetation.