湘江下游流域-河网-枢纽的水文水动力模拟北大核心CSCD

应用自主开发的集成模型搭建了考虑长沙航电枢纽高频调度的湘江下游流域-河网系统水文水动力计算系统,采用区域2016—2021年80余站高频监测(1次/5~60 min)、30 m精度土地利用和详细河道水下地形等数据对模型进行配置、检验和验证,对比计算有、无枢纽调度下的河网水动力和淹没差异。结果表明:水位流量计算值与高频实测值吻合优良,在湘潭、朗梨等站的纳什系数大于0.91;调度造成回水区枯水期水位抬升和流速降低,改变了河网水位和流量小尺度波动节律,在浏阳河等支流下游局部时段出现反向流动;计算出了1%、50%、99%等来流频率下河网水位和流速分布,调度增加了上游干支流回水区心滩、边滩的平、枯季淹没频率。本研究为科学评估枢纽高频调度对上下游河网水动力影响提供依据。

Integrated modelling of hydrological and hydrodynamic processes in watershed-rivers and navigation-hydropower project system of lower Xiangjiang River

An integrated hydrological and hydrodynamic model is developed and applied to the watershed and river network system of the lower Xiangjiang River, coupled with high-frequency operations of the Changsha navigation-hydropower project. It is configured, validated and verified using detailed riverbed topography, high-frequency data collected from nearly 80 stations at the time interval of 5 to 60 min during 2016-2021, and land use data with a resolution of 30 m. And the hydrodynamics and inundation processes with and without the project are calculated and compared. The results show the calculated water levels and flows in the rivers agree well with the high-frequency measurements, and the Nash Sutcliffe efficiency (NSE) is greater than 0.91 from the verification of Xiangtan, Langli, and other stations. The project operation and scheduling raised the water level and reduced the average flow velocity significantly in the backwater sections of the main river and its tributaries in the dry season, so that small-scale fluctuations in water level and flow were intensified and even reverse flows occurred in certain sections of the lower Liuyang and other rivers. For the incoming hourly flow at the frequencies of 1%, 50% and 99%, the calculations of water level and flow velocity in the river network reveal that the project scheduling increased the frequency of inundation in the sections of sand shoals and point bars in the upstream of the main river and its tributaries in the normal and dry seasons. This study demonstrates a new method and its application for quantitative assessment to the impacts of high-frequency scheduling of dams on the river system.