Modeling the tidal dynamic changes induced by the bridge in Jiaozhou Bay, Qingdao, China

Cross-bay bridge is familiar in the world. However, few works have been conducted on the environment change due to bridge construction. Jiaozhou Bay (JZB) Bridge, Qingdao was built in 2011, with the length of 26.75 km and total piers length accounting for 10% of the bridge length. A numerical model was established with actual pier size, gap and location, thus fine grids, to study the tidal dynamics change due to the bridge pier construction. In the model, piers were recognized as islands to simulate the actual tidal condition. Model results indicated that the tidal current changed obviously around the piers while unobvious 200 m far from the piers. Although tiny impact due to a single pier, accumulated blockage effect of the whole bridge could induce the tidal change in the bay entrance. Due to the bridge construction, the difference of tidal elevation between the inside water and outside water increased. Whereas, both tidal current and residual current decreased significantly in the bay entrance. During spring tide, tidal prism decreased by 1.7% induced by the pier blockage effect, which equals to 140 times more than the piers bulk in the tidal range.