Combined Effect of Tides and Wind on Water Exchange in a Semi-Enclosed Shallow Sea

Jiancheng Shang,Lei Tao,Yuanyi Li,Zhenhua Nie,Rui Chen,Haiying Liu,Jian Sun,Dekui Yuan

doi:10.3390/w11091762

Abstract

The Bohai Sea is a semi-enclosed shallow sea in China, where the tides and wind are the dominant factors contributing to the water exchange with the Yellow Sea. However, existing studies on this water exchange primarily consider only the effect of tidal action, neglecting the contribution of wind. In this study, numerical models were used to simulate the hydrodynamic processes and tracer transport, with the consideration of both tides and wind. Based on the models, the two time scales, age and half-life, are applied to study the water exchange in the Bohai Sea quantitatively. The results show that the age and half-life decrease significantly when wind is included in the simulation, revealing that wind is an important contributor to the water exchange in such a semi-enclosed shallow sea. Under the combined forcing of tides and wind, the water transport in the Bohai Sea becomes clockwise, in contrast with the counterclockwise transport driven by the tides only. The seasonal-varying wind leads to a fluctuation of water exchange in an annual cycle, with the stronger water exchange in the northern (Liaodong Bay) and the western (Bohai Bay) regions of the Bohai Sea in winter and in the southern part (Laizhou Bay) in summer.

Highlights

Regions around semi-enclosed seas are generally less hazardous for shipping traffic and are home to a large portion of the world’s population
Due to its semi-enclosed nature, water exchange with the Yellow Sea and the larger Pacific Ocean is weak leading to a buildup of land-based pollution [11]
The tide is an important factor relating to the water exchange in the

Summary

Introduction

Regions around semi-enclosed seas are generally less hazardous for shipping traffic and are home to a large portion of the world’s population. These large populations generate high levels of pollution, which is discharged into the ocean and can have significant effects on the natural environment. Semi-enclosed seas around the world often face environmental problems [1,2,3,4,5,6,7,8,9,10]. Due to its semi-enclosed nature, water exchange with the Yellow Sea and the larger Pacific Ocean is weak leading to a buildup of land-based pollution [11]. The reduction of the pollution load is one of the important measurements of the water quality improvement, knowing the water exchange rate, which is an intrinsic condition determining the physical self-purification ability and water quality, is necessary to protect the Bohai Sea from water quality degradation

Methods

Results

Conclusion