基于GPS的洪泽湖水流流场质点示踪及数值模拟

Particle tracing and numerical simulation of flow field in Hongze Lake based on GPS tracer experiment

针对不同水文气象条件下湖泊真实流场描述的难题,通过在洪泽湖主要入口分别投放GPS示踪器,实现了对湖泊表层水流轨迹、方向的实时监测,形成洪泽湖初步流场图。野外示踪实验结果表明:流经湖泊中心区域的水流运动轨迹均为自西向东的曲线;入湖流量较小时水流难以进入湖泊中心流场,入湖流量较大时流速空间分布不均,流场较复杂;小流量入湖条件下水流运动受到湖泊表面风场的影响,流量较大时水流流动的主要影响因素为湖泊自身的流场。同时,构建了不同入湖流量条件下的洪泽湖二维水动力数值模型,水动力模型模拟的流场分布基本符合水流质点GPS示踪实验的结果,两者拟合较好。本次研究揭示了洪泽湖的真实流场,基于GPS的示踪方法可用于分析河流湖泊的水动力空间变化,为泥沙、污染物质的输移和扩散提供了重要参考依据。

To describe the real flow field of the Hongze Lake under different hydrologic and weather condition,GPS tracers were installed at the main entrances of the lake to visualize the real-time tracking of water surface trajectory and flow direction,and the preliminary flow field map of the Hongze Lake was formed.The field tracer experiments show that the water flow path in the center of the lake is a curve from west to east.When the inflow is small,it is difficult for water to enter the central flow field of the lake.When the inflow is large,the spatial distribution of flow velocity is uneven and the flow field is complex.It is also found that the water flow is affected by the surface wind field of the lake under the condition of small flow rate,whereas the main influencing factor of water flow is its own flow field when the flow rate is large.At the same time,a two-dimensional hydrodynamic model was built to simulate the flow field of Hongze Lake under different inflow conditions.The simulation result shows that the simulated flow field is basically consistent with the result of the GPS tracer experiment.GPS based tracking experiment method is applicable to the analysis of the spatial variation of hydrodynamic forces in rivers and lakes,it can also provide some insights for the transport and diffusion of sediment and pollutants.