The water exchange capacity of a shallow coastal lagoon is sensitive to its environment and hydrodynamics. In this study, the responses of hydrology and climate change on the water exchange characteristics of such a shallow environment are investigated in the Qilihai lagoon. Water circulation and transport are simulated by a numerical model and the water exchange capacity is evaluated by the water flushing and residence time. Our analysis reveals that water exchange with seasonal characteristics is the strongest in summer due to large runoff and is the weakest in winter due to ice roughness. The shallow terrain variation influences water exchange, which is more obvious for the transverse rather than longitudinal direction. Without an ice cover, runoff is the most significant influence on water exchange. This effect is nonlinear and in accordance with a two-terms exponential formula. Water transport time can be significantly reduced by the presence of wind. Westerly winds accelerate water exchange the most. The influence of mean water level on water exchange can be separated into two phases dominated by bathymetry. Ice dominates water exchange and mainly influences the shallow area during winter. Furthermore, the presence of chlorophyll-a positively correlates with water exchange dominated by hydrodynamics. The distribution of sedimentary heavy metal contamination has no direct link with water exchange, which mainly occurs in tidal inlets and the river mouth, and is controlled by source loading. Our results support the current understanding of what mechanisms influence water exchange capacity and establish a theoretical foundation for environmental protection in global shallow coastal lagoon regions.

沿海浅水泻湖的水交换能力对其环境和流体动力学敏感。在这项研究中，调查了七里海泻湖中水文和气候变化对这种浅层环境的水交换特征的响应。通过数值模型模拟水的循环和输送，并通过冲洗和停留时间评估水交换能力。我们的分析表明，具有季节性特征的水交换在夏季由于径流量大而最强，而在冬季由于冰的粗糙度最弱。浅层地形变化影响水交换，这在横向而不是纵向上更为明显。没有冰盖，径流对水交换的影响最大。此效应是非线性的，并且符合两项指数公式。有风可以大大减少水的运输时间。西风最大程度地促进了水交换。平均水位对水交换的影响可以分为两部分，以测深法为主。冰在冬季占主导地位，主要影响水交换。此外，叶绿素a的存在与水动力主导的水交换正相关。沉积物中重金属污染的分布与水交换没有直接关系，水交换主要发生在潮汐口和河口，并受水源负荷控制。