水电能源科学

为深入分析沱湖流域的水动力特性，从定量和定性角度出发掌握有无风场作用下沱湖的水体更新能力，基于MIKE21软件建立研究区域二维水动力模型，利用2018、2021年樊集和山西庄闸水位过程进行率定验证，并模拟流场分布；进一步耦合水体换水周期数值模拟方法，采用2018、2020、2021年汛期资料进行换水周期计算，对比风场作用和无风条件下沱湖水体更新时间均值的空间变化，选取湖区6个采样点，提取各采样点随时间变化的浓度序列，分析沱湖水质各特征部位的水体更新变化规律。结果表明，风是决定沱湖流场形态的重要因素，风的作用一定程度上改变了该湖区的流场结构；沱湖水体更新能力具有空间异质性，西部湖区水体更新速度快、东部湖区水体更新速度慢；在无风条件下，山西庄闸边界附近水体更新速度要明显快于南部湖心，尤其在大水年(2020年)水体更新时间最短，污染物运移速度最快，表明怀洪新河入流对西南部湖区有正向作用，增强了湖区的水动力条件，促进了西南部水体的对流和混合，减少了西南部湖区的水体更新时间；有风条件下，2018、2020、2021年湖泊水体更新时间空间分布均值分别比无风时减少了27、2、6 h,说明风速场是影响沱湖污染物运移的重要驱动力。研究结果旨在丰富沱湖流域水动力特性和水体交换能力方面的相关研究，为后续沱湖水质改善措施和调水方案优化提供依据。

To deeply analyze the hydrodynamic characteristics of the Tuohu Lake Basin, the water body renewal capacity of Tuohu Lake with and without wind field effects was investigated from quantitative and qualitative perspectives. A two-dimensional hydrodynamic model of the study area was established based on MIKE21 software. The water level processes at Fanji and Shanxizhuang Sluices in 2018 and 2021 were used for calibration and verification, and the flow field distribution was simulated. Furthermore, the numerical simulation method of water exchange cycle was coupled, and the flood season data of 2018, 2020, and 2021 were adopted to calculate the water exchange cycle. The spatial variation of the mean water body renewal time of Tuohu Lake with or without wind field action was compared. Six sampling points in the lake area were selected to extract the concentration sequences of each sampling point changing with time, and the water body renewal variation law of each characteristic part of Tuohu Lake water quality was analyzed. The results show that wind is an important factor determining the flow field pattern of Tuohu Lake, and the action of wind changes the flow field structure of the lake area to a certain extent. The water body renewal capacity of Tuohu Lake has spatial heterogeneity, with the water body renewal speed in the western lake area being fast and that in the eastern lake area being slow. Under windless conditions, the water body renewal speed near the boundary of Shanxizhuang Sluice is significantly faster than that in the southern central lake. Especially in the high-flow year(2020), the water body renewal time is the shortest, and the pollutant migration speed is the fastest, indicating that the inflow of the Huaihongxin River has a positive effect on the southwestern lake area, enhances the hydrodynamic conditions of the lake area, promotes the convection and mixing of water bodies in the southwestern part, and reduces the water body renewal time in the southwestern lake area. Under wind conditions, the average values of spatial distribution of lake water body renewal time in 2018, 2020, and 2021 are reduced by 27, 2, and 6 hours respectively compared with those under windless conditions, indicating that the wind speed field is an important driving force affecting the pollutant migration in Tuohu Lake. The research results aim to enrich the relevant research on the hydrodynamic characteristics and water body exchange capacity of the Tuohu Lake Basin, and provide a basis for the subsequent water quality improvement measures and optimization of water diversion schemes in Tuohu Lake.