Simulation Analysis Of The Influence Of Water Control Project On Water Exchange Cycle In Poyang Lake Based On EFDC Model

Poyang Lake is a lake connected to the Changjiang River,There is a complex river and lake relationship with the Yangtze River,which presents a highly dynamic change of water situation.The proposed Poyang Lake water conservancy project will inevitably lead to the change of the hydrological situation in Poyang Lake.The water exchange cycle is an important ecological and hydrological variable.In this paper,the twodimensional hydrodynamic model of Poyang Lake constructed by the EFDC model is used to simulate the scenario of 2000(flat water year),2004(dry water year)and 2010(year of rich water)respectively according to the planned water control project scheduling scheme,and the simulation results are used.The water depth,water level,dry and wet,and flow rate are calculated in Poyang Lake,and the effects of different water conservancy projects on the water exchange cycle are analyzed.(1)In the flat water year,the construction of Poyang Lake water control project will slow down the water exchange cycle in Poyang Lake.The annual average water exchange period of the hub will increase by 1.5 days than that of the non hub annual water exchange period,and the speed of water renewal is slowed by 11.1%.Especially during the impoundment period,the hub water transfer cycle increased by 10.3d,which increased by 53.2%.In the year,the fluctuation range of the water exchange period is very large,the water exchange cycle is two times more than 70 d,the minimum value of the water exchange period is only 4.3d,the difference is 65.7d,and the ratio is 16.3 times.(2)In the dry year,the average annual water exchange period of the hub is 19.7d,which is 3.2d more than the non hub water exchange period,and the speed of water renewal slows down by 19.4%.In the low water period,the key storage period,the storage period of the Three Gorges Reservoir and the adjustment period of the Three Gorges reservoir,there is an increase in the water transfer cycle of the hub.In particular,the water exchange cycle increases by 26.9d under the hub situation,and the increase of the water exchange period is more obvious.(3)In the year of abundant water,there is a whole rise in the water transfer cycle of the hub,but there is a local decline.The annual average water exchange period and the annual average water exchange period of the hub are 12.5d and 14.3d,respectively,increasing by 1.8d,and increasing by 14.4%.The water control project has a great influence on the water transfer period of the hub and the reservoir water storage period.In the low dry season and the compensation regulation period,the water exchange cycle has little influence.(4)From the whole year of the whole,the average annual water exchange cycle of the flat,dry and plentiful is increased by 1.5 days,3.2 days and 1.8 days,respectively,11.1%,19.4% and 14.4% respectively.In the year of abundant water and the water conservancy project,the water exchange cycle has a relatively small influence on the water exchange period,and the water transfer project in the dry water year is changed to Poyang Lake.The effect of the cycle is more obvious.(5)From the different dispatching period analysis,in the low water period,the water control project has a great influence on the water exchange cycle in the dry water year,and the water exchange cycle in the flat water year has the smallest influence.In the river and lake connection period,the water control project has no influence on the water exchange cycle of the flat,dry and rich hydrologic years.The influence degree of the water cycle is the dead water year,the flat water year and the rich water year respectively.In the Three Gorges reservoir water storage period,the water transfer cycle of the hub has the corresponding shortening trend,but it has the greatest influence on the water exchange cycle of the flat water year;in the period of compensation adjustment,the water transfer project has a great influence on the water exchange cycle of the dry water year and the water exchange in the year of the flood season.There is no effect on the cycle.