He Wei, Zhang Xuetong, Huangjin Yaxuan, Ren Yufeng, Bi Yonghong
National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing 210098, China; College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China; Cooperative Innovation Center for Water Safety & Hydro Science, Hohai University, Nanjing 210098, China; College of Future Technologies, Hohai University, Nanjing 210098, China.
National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing 210098, China; College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China; Cooperative Innovation Center for Water Safety & Hydro Science, Hohai University, Nanjing 210098, China.
Sci Total Environ. 2025 Aug 20;991:179858. doi: 10.1016/j.scitotenv.2025.179858. Epub 2025 Jun 20.
Understanding the effects of a hydrological regime on the eco-environment of a tributary in a river-type reservoir is essential because reservoir regulations substantially change the freshwater ecosystem in the tributary. The construction of cascade reservoirs upstream of the Yangtze River has significantly altered the water regime and impacted reservoir ecosystems. However, the effects of water level rising (WLR) on the temperature-nutrient-phytoplankton aspects lack research. A three-dimensional model, covering the Three Gorges Reservoir (TGR) and one of its tributaries, the Xiangxi River (XXR), was built based on the Environmental Fluid Dynamics Code (EFDC). The model was calibrated and validated using measured data during 2018 and 2019 and adopted to determine the associations between reservoir operation and the tributary eco-environment. The spatiotemporal distributions of hydrodynamics, temperature, nutrients, and phytoplankton biomass were numerically analyzed under various WLR scenarios during the flood season. The results indicated that WLR intensified mid- and bottom-layer reversed-density currents, decreased water temperature, and, hence phytoplankton biomass, which increased total nitrogen (TN) and total phosphate (TP). 5-m WLRs of 15-day duration reduced Chl-a concentrations by up to 6.18, 2.53, and 0.83 μg/L, in June, July, and August, respectively. Higher magnitudes and shorter durations enhanced the reduction effect of WLR on Chl-a. A 1-m WLR over 15 days resulted in a 0.72 μg/L reduction. These findings suggest WLR as a viable strategy for phytoplankton biomass regulation and algal bloom control in river-type reservoirs.
了解水文情势对河流水库支流生态环境的影响至关重要，因为水库调度会显著改变支流中的淡水生态系统。长江上游梯级水库的建设已显著改变了水流情势，并对水库生态系统产生了影响。然而，水位上升（WLR）对温度-营养物质-浮游植物方面的影响缺乏研究。基于环境流体动力学代码（EFDC）建立了一个涵盖三峡水库（TGR）及其支流之一香溪河（XXR）的三维模型。该模型利用2018年和2019年的实测数据进行了校准和验证，并用于确定水库运行与支流生态环境之间的关联。在汛期不同水位上升情景下，对水动力、温度、营养物质和浮游植物生物量的时空分布进行了数值分析。结果表明，水位上升加剧了中层和底层的逆密度流，降低了水温，进而降低了浮游植物生物量，增加了总氮（TN）和总磷（TP）。持续15天的5米水位上升分别使6月、7月和8月的叶绿素a浓度降低了6.18、2.53和0.83μg/L。更高的幅度和更短的持续时间增强了水位上升对叶绿素a的降低效果。15天内1米的水位上升导致叶绿素a浓度降低0.72μg/L。这些发现表明，水位上升是调节河流水库浮游植物生物量和控制藻华的一种可行策略。
