ABSTRACT Lake Urmia, located in northwestern Iran, a hypersaline lake, divided into north and south basins by a causeway. The lake has been facing a serious environmental crisis, due to water mismanagement in the basin. To address this problem, an analysis of the hydrodynamic behavior and of salinity distribution is important. The three-dimensional numerical model MIKE 3 Flow Model FM was employed in this study. Model sensitivity analyses revealed that wind speed, friction coefficient, and vertical eddy viscosity are effective parameters on both flow velocities and salinity distribution, while bottom roughness height has minor effects on surface velocities. Reduced value for vertical eddy viscosity improves the simulation of the velocity field and has an adverse effect on salinity distribution. The UNESCO density function leads to an overestimation of density. Yet, final model results are accurate enough to reproduce the salinity distribution over the lake, revealing that the salinity difference between North and South basins of Lake Urmia increases significantly in the wet season, due to southern rivers inflows by snowmelt. For the simulated periods of 1986–1987 and 2004–2005, natural and man-induced drought hydrological conditions, the direction of flows was from south to north, with a much lower net flow in the latter period. This decrease in the exchanged flows causes higher salinity difference among basins. Results indicate that the present model could be run for any time period in both normal and drought conditions and can satisfactorily simulate the hydrodynamic characteristics and salinity distribution of Lake Urmia for management purposes.

中文翻译：

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研究 MIKE 3 流动模型 FM 模拟高盐度湖泊的流体动力学和盐度分布的能力：以乌尔米亚湖（伊朗）为例

摘要乌尔米亚湖位于伊朗西北部，是一个高盐度湖泊，被堤道分为南北盆地。由于流域的水资源管理不善，该湖一直面临着严重的环境危机。为了解决这个问题，对水动力行为和盐度分布的分析很重要。本研究采用三维数值模型 MIKE 3 Flow Model FM。模型敏感性分析表明，风速、摩擦系数和垂直涡粘性是流速和盐度分布的有效参数，而底部粗糙高度对表面速度的影响较小。垂直涡流粘度值的降低改善了速度场的模拟，并对盐度分布产生了不利影响。联合国教科文组织的密度函数会导致对密度的高估。然而，最终的模型结果足以再现湖泊的盐度分布，表明由于融雪流入南部河流，乌尔米亚湖南北盆地之间的盐度差异在雨季显着增加。模拟的1986-1987年和2004-2005年，自然和人为干旱水文条件下，水流方向由南向北，后期净流量低得多。交换流量的减少导致流域之间的盐度差异更大。