鄱阳湖枯水水位及流速时空分布模拟

TEMPORAL AND SPATIAL SIMULATION OF WATER LEVEL AND VELOCITY DURING LOW WATER LEVEL STATISTICAL YEAR IN LAKE POYANG

大型通江湖泊鄱阳湖水文节律独特,水位和流速是其生态系统功能维持的关键因子。为探究其水位和流速时空特征,基于EFDC(Environmental Fluid Dynamics Code)模型,利用五河及湖口水文数据、气象数据及湖底高程作为输入条件,模拟出鄱阳湖的枯水水文统计年(2010-07-01~2011-06-30)水位和流速时空变化过程。模拟结果表明:(1)星子等4个站点拟合程度较好(r2>0.85),达到了复杂湖库水动力模拟的精度。(2)高水位期,湖区水位空间分布无明显差异,水深直接受湖底高程影响,自上游至下游呈逐级递增;低水位期,鄱阳湖水位在空间上出现明显差异,湖区外缘水位至入江水道逐级递减,水深分布空间差异不大,仅入江水道处水深明显高于其他水域。(3)流速也包括一系列时空变化特征,如高水位时期流速小于低水位时期;除大水面时期外,深水道流速大于主湖区;高水位时期上游流速略高于下游,但其他月份,北部入江水道流速均大于南部湖区等。(4)流速与水位关系密切,且不同水位对应流速大小及分布有所差异。鄱阳湖枯水水位和流速模拟分析可为大型湖库枯水水情管理提供科学参考和辅助决策支持。

Lake Poyang,as a large lake naturally connected to the Yangtze River,owns different hydrological characteristics.Water level and velocity are the key environmental driving factors to maintain ecological function of the lake aquatic ecosystem.In this paper,EFDC（Environmental Fluid Dynamics Code） was constructed to simulate the water level and water velocity changes in Lake Poyang during the low water level statistical year（from June 30,2011 to July 1,2010）.And the hydrological data including water level and discharge from five inflow rivers and Hukou station,meteorological data and DEM were as input files to run the model.The paper drew the following conclusions,（1） The simulation results of four hydrological stations showed great fit（r^2〉0.85）.（2）During the high water level period,there was no obvious spatial difference among water levels in Lake Poyang.Thereby the water depth was mainly determined by lake＇s elevation and increased gradually from upstream to downstream.During low water level period,spatial difference of water level existed and water level decreased from lake＇s boundary to channel connected to Yangtze River.The distribution of water depth was not heterogeneous,excepting in narrow channel where water depth was higher than other lake zones.（3）Water velocity in Lake Poyang had series of characteristics,for instance,water velocity during high water level was slower than during lower water level period;the water velocity in narrow channel was significantly faster than in other region,excepting in high water level period.The water velocity in the northern zone was faster than southern area in majority of months.（4） The flow velocity was closely related to water level and different water level would drive different distribution of flow velocity.The water level and velocity simulation research laid a foundation for water management during dry period of large water bodies lately.