摘要
水温结构是湖库生态系统演化的重要基础,热分层稳定性对深水湖库水体物理、化学和生物演化具有重要影响,因此研究水体热分层特征及关键控制因素具有重要意义。本文运用DYRESM水动力模型模拟了红枫水库2014年全年的水温变化特征,并对影响水体热分层结构的关键控制因素进行了探究。结果表明:1) DYRESM水动力学模型可有效模拟红枫水库的水体热分层特征及时间演化规律,可准确预测水体热分层形成和消亡的时间及去分层强度。2)气温变化对水库水体热分层具有明显影响,增温可加速水体热分层的形成,造成温跃层下潜和去分层延迟;短波辐射的增强(<40%)不会对红枫湖水温结构造成明显影响,但可导致去分层发生时间后延;风速是水体热分层稳定性的敏感因素,当风速增加40%后,热分层演化发生较大变化,表现在6~9月份中层及底层水温大幅升高(从9℃上升到14℃),去分层时间提前30天,相应造成分层期缩短。
The vertical structure of water temperature is an important basis for the evolution of lake/reservoir ecosystem. The stability of thermal stratification has important impacts on physical,chemical and biological evolutions of deep-water lakes and reservoirs. Therefore,it is of great significance to study the characteristics and key control factors of water thermal stratification. In this study,the DYRESM hydrodynamic model was applied to simulate the water temperature variation of the Hongfeng Reservoir in 2014,and the key factors affecting the water thermal stratification were explored. Our results showed that: 1) the DYRESM model can effectively simulate the characteristics and time evolution of the water thermal stratification and can accurately predict the formation and extinction of the thermal stratification and the intensity of de-stratification. 2) the temperature changes have significant impacts on the thermal stratification,and the increasing temperature can accelerate the formation of the water thermal stratification,resulting in the thermocline submergence and the delay of de-stratification. The enhancement of shortwave radiation( <40%) will not significantly affect the water temperature structure,but may cause the time delay of de-stratification. The wind speed is a sensitive factor of the thermal stratification stability. When the wind speed increases by 40%,the water temperatures in the middle and bottom waters will increase significantly( from9 to 14 ℃) from June to September,and the de-stratification will occur 30 days earlier,correspondingly,the stratification period will be shortened.
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