拟建鄱阳湖水利枢纽工程对长江干流流量影响的模拟

维系江湖关系的重要基础是江湖之间的物质通量,而江湖之间物质通量的核心内容是水的通量.规划中的鄱阳湖水利枢纽工程,以"一湖清水"为建设目标,坚持"江湖两利"的原则,按"调枯不控洪"方式运行.目前,国内学者对拟建的鄱阳湖水利枢纽工程可能导致湖泊影响方面的研究较多,但对该工程能否实现或维持"江湖两利"方面的研究较少.本文采用二维水动力模型,针对拟建的鄱阳湖水利枢纽工程和规划中的水位调度方案,分别从湖泊丰水期和枯水期两个时段,选择鄱阳湖丰、平、枯3种典型年型,在无枢纽与有枢纽两种情景模拟的基础上,定量分析丰、平、枯3种典型年枢纽工程的水位调度方案对长江干流流量的可能影响.模拟结果表明:在一个鄱阳湖水利枢纽工程水位调度周期中,无枢纽状态与有枢纽情景下湖泊外排到长江干流的径流总量差异很小,从模拟的年份来看,有枢纽外排减少量在0.2%~0.7%之间变化,基本维持了有枢纽与无枢纽状态下的水量平衡,但在一定程度上改变了湖泊外排长江干流水量的分配时间,使不同年型丰水期的湖泊外排水量有所减少,而在湖泊和长江低枯水期,对长江流量则有一定的增排作用,且增排效果为枯水年型平水年型丰水年型,不同年型的增排比例在2.1%~17.0%之间变化;在丰水期湖泊水位偏低,且枢纽位置的实际水位严重不足9 m的年型情况下,按照枢纽工程的水位调度方案要在9月15日将湖泊水位提升至14~15 m是难于实现的,现有的枢纽工程调度方案在这种情况下缺乏可操作性,有进一步细化和优化的空间.

Simulation of impacts of Poyang Lake Hydraulic Project on the flow of the Yangtze River using an EFDC model

Mass flux is an important basis for maintaining the relationship between lakes and rivers, while the key of mass flux is water flux. Aiming to a goal of constructing a clear water that are conducive to both the Yangtze River and Poyang Lake, the Poyang Lake Hydraulic Project (PLHP) in planning will be operated according to a proposed water level regulating scheme in the view of ecology, in which is controlling over the lake level in the dry season instead of the wet season. By using two-dimensional hydrodynamic model, this paper conducts a quantitative analysis concerning the potential impacts of the water level regulating scheme of PLHP under three typical hydro-years (wet, normal and dry years) on stream flow of the Yangtze River. According to the simulation results, during a PLHP water level regulating period, the difference, the discharge from the lake to the Yangtze River is very small, only varied from -0.2% to -0.7% compared with two modeling scenarios (with or without the PLHP). The discharge under those two scenarios is basically maintained in a balanced state, though the seasonal distribution time from the lake to the Yangtze River is changed. During the dry season, the project has minor impact on the flow of the Yangtze River, or even increases the amount of water discharges. The dry year has a maximum effect of the increased discharge, followed by normal year and the third by wet year. The increased discharge in different hydro-years varies from 2.1% to 17.0%. In normal year and dry year, the lake level before the beginning of the PLHP regulation is much lower than the highest regulated water level of 9 m, so that the existing PLHP regulation scheme, which proposes to regulate the water level to 14-15 m on September 15, has obvious defects and need a further optimization.