Study on the impact of South-to-North Water Diversion Project on the exchange characteristics of the lower level lake water of Nansi Lake
[Objective]The South-to-North Water Diversion Project utilizes Nansi Lake as a water transmission channel,and the flow field changes in the lower level lake water of Nansi Lake are more complicated after the project is in operation.The purpose of this paper is to study the effects of the water transfer project on the exchange characteristics of water in the lower level lake wa-ter of Nansi Lake and various subdistricts.[Methods]Based on the collection of topography,rainfall,evaporation and wind data of the lower level lake water of Nansi Lake,a convective diffusion model of the lower level lake was constructed,and the model rate was determined and verified.At the same time,a total of three flow conditions,namely,50 m3/s,the actual flow during the water transfer period in 2020-2021,and the design flow of 125 m3/s,were selected for simulation and analysis.[Results]The model result show that the water level difference from Hanzhuang Station of the lower lake to the secondary dam under the three flow conditions is 0.06 m,0.12 m,and 0.36 m,respectively,for 148 days of water transfer.The water level specific declines from Hanzhuang station to the secondary dam were 1.0×10-6,2.1×10-6,and 6.2×10-6 respectively.Lower lake mean flow ve-locity increased by 0.15 cm/s,0.54 cm/s,and 0.87 cm/s,respectively.The percentage of stagnant and stagnant water area has been decreasing,and the mobility of the lake's water bodies has increased significantly.Case 2 simulated a total of 660 mil-lion m3 of water into the lower lake and 630 million m3 of water out of the lower lake,with 67%of the old body of water in the lower lake and 33%of the water transferred from outside.[Conclusion]Lower lakes have progressively longer water renewal times from south to north and from east to west for the same flow conditions.The renewal times of the lower lake water body under the three flow conditions were 77 d,78 d,and 53 d,respectively.The result of the study help to quantitatively analyze the exchange process of the lower lake water under the water transfer situation,which is a reference for the scheduling and operation of the Nansi Lake section of the South-to-North Water Diversion East Route Project.
numerical simulationhydrodynamic characteristicswater exchangeupdate timeflowlower lake of Nansi Lake
国家科技期刊平台
NSTL
万方数据
