Author(s): Zhi-Chao Dong, Cui-Ping Kuang, Yue Ma, Jie Gu
Linked Author(s): Zhichao Dong
Keywords: Qilihai lagoon, tidal inlet, hydrodynamic, water exchange, residence time
Abstract: Qilihai lagoon, located in Changli Gold Coast nature reserve, Qinhuangdao city, Hebei province, is one of the most typical and representative wetland lagoon in China. The tidal inlet of Qilihai lagoon is like an open channel with the length of 1700m and the geometry of tidal inlet is one of the key control factors of the lagoon system. Due to that, its changes will influence the system's hydrodynamic characteristics. Studying the influence of tidal inlet width on current and water exchange is carried out so that a hydrodynamic and conservation substance transport model can be established by MIKE21 to simulate four scenarios with different tidal inlet widths, i. e. , 100m, 200m, 300m and 400m respectively. Computed tracer mass is dealt with Eulerian method based on solving the convection-diffusion equation and least-squares method to fit nonlinear curve. Then the residence time is obtained to analyze water exchange capacity, which can provide a scientific basis for the tidal inlet design. The numerical results indicate that: 1) there is an anti-clockwise circulation inside Qilihai lagoon near the tidal inlet and the area of circulation is the largest for the moment of flood slack; 2) with the increase of inlet width, both flood and ebb discharge increase and the range of water level turns larger, however, the mean current speed from the tidal inlet into lagoon becomes smaller; 3) widening inlet width will reduce water residence time and enhance the water exchange capacity in the lagoon
Year: 2017