State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610065, China.
Guizhou Academy of Water Conservancy, Guiyang, 550002, China.
Environ Sci Pollut Res Int. 2018 Sep;25(25):24975-24991. doi: 10.1007/s11356-018-2535-8. Epub 2018 Jun 22.
Considering the highly complex flow structure of saltwater lakes during freshwater supplementation, a three-dimensional numerical model was developed to simulate suspended sediment transport in saltwater lakes. The model was validated using measurements of the salinity and sediment concentration during a pumping test at Yamdrok Lake. The simulation results were in quantitative agreement with the measured data. The observed and simulated results also indicated that the wind stress and vertical salinity gradient have a significant influence on salinity and sediment transport in a saltwater lake. The validated model was then used to predict and analyze the contributions of wind, the supplement flow rate and salinity stratification to the sediment transport process in Yamdrok Lake during continuous river water supplementation. The simulation results showed that after the sandy river water was continuously discharged into the saltwater lake, the lateral diffusion trends of the sediment exhibited three stages: linear growth in the inflow direction, logarithmic growth in the wind direction, and stabilization. Furthermore, wind was the dominant factor in driving the lake flow pattern and sediment transport. Specifically, wind can effectively reduce the area of the sediment diffusion zone by increasing the lateral sediment carrying and dilution capacities. The effect of inflow on the lake current is negligible, but the extent of the sediment turbidity zone mainly depends on the inflow. Reducing the inflow discharge can decrease the area of the sediment turbidity zone to proportions that far exceed the proportions of inflow discharge reductions. In addition, the high-salinity lake water can support the supplemented freshwater via buoyancy forces, which weaken vertical mixing and sediment settlement and increase lake currents and sediment diffusion near the surface.
考虑到淡水补给期间盐水湖水流结构高度复杂，开发了一个三维数值模型来模拟盐水湖中悬浮泥沙的输运。该模型使用羊卓雍错抽水试验期间的盐度和泥沙浓度测量数据进行了验证。模拟结果与实测数据定量吻合。观测和模拟结果还表明，风应力和垂直盐度梯度对盐水湖的盐度和泥沙输运有显著影响。验证后的模型随后用于预测和分析在连续河水补给期间，风、补给流量和盐度分层对羊卓雍错泥沙输运过程的贡献。模拟结果表明，当含沙河水持续排入盐水湖后，泥沙的侧向扩散趋势呈现出三个阶段：沿入流方向呈线性增长、沿风向呈对数增长和稳定。此外，风是驱动湖水流动模式和泥沙输运的主导因素。具体来说，风可以通过增加侧向泥沙携带和稀释能力，有效地减少泥沙扩散区的面积。入流对湖水流动的影响可以忽略不计，但泥沙浑浊带的范围主要取决于入流。减少入流排放可以使泥沙浑浊带的面积减少到远超过入流排放减少比例的程度。此外，高盐度湖水可以通过浮力支持补充的淡水，这会减弱垂直混合和泥沙沉降，并增加表层附近的湖流和泥沙扩散。
