Simulation of the Impact of Breakwaters on HydrodynamicEnvironment in Laizhou Bay, China

The construction of two sand breakwaters in Guangli Port might cause changes to the marine environment of Laizhou Bay. Tidal flow field and conservative substance transport are simulated by a two-dimensional hydrodynamic model MIKE21 to assess the impact of breakwaters on the hydrodynamic environment. The results show that the construction has minor influences on the tidal currents. The changes mainly occur in the region near the port (about 20 km² in area). The directions of currents during flood tide and ebb tide veer less than 20 degrees, and a maximum change in speed of (0.87 ± 0.1) m s⁻¹ occurs in between the breakwaters during ebb tide. However, the self-purification ability of Laizhou Bay is significantly reduced according to the conservative substance transport model, especially in the southwest (about 100 km from the Guangli Port to the estuary of Xiaoqinghe River), where the water exchange rate decreases by 10% – 20%. The breakwaters slow down the northward current during ebb tide, which causes the accumulation of pollutants.