Numerical Modeling of the Seasonal and Interannual Variability of the Water Transport Through the Bohai Strait

Based on a high-resolution unstructured-grid numerical model, the multiscale temporal variation characteristics of water transport through the Bohai Strait was systematically analyzed. The water transport through the Bohai Strait exhibits obvious seasonal and interannual variation except the long-term trend, and inflow and outflow exhibits alternative spacial distribution. Temporal variation of the net flux in southern part of the strait coincides with that of the Yellow River’s runoff, while in the central and northern sectors, the correlation is not significant. Seasonal transport shows a “bimodal” pattern with higher volumn transport in autumn and winter, which is influenced significantly by strong winds, water level gradient across the strait, and seasonal variation of the Yellow River runoff. From 2003 to 2008, variations in water transport were primarily controlled by local wind fields and water level gradient across the strait. The water transport variation in the main inflow channel along 38°36′N modulates the water exchange across the strait. Notably, in 2005 and 2012, the water transport through the strait reached its lowest volumn, which decreased by approximately 6.3×10³ and 6.2×10³ m³/s respectively from the average. During that period, the inflow in the main channel near 38°36′N increased by about 5.5×10³ and 1.2×10⁴ m³/s respectively compared to the average inflow in the northern Bohai Sea, while outflow in the central and southern parts of the strait increased by about 1.1×10³ and 4.2×10³ m³/s, respectively, with the change in outflow being much less than that in inflow.