不同类型水库对库区及河道水温的影响

Influence of Different Types of Reservoirs on Water Temperature in Reservoir and Its Downstream River

水库运行方式是引起河流水文情势和水体热量变化的人为可控因素。选取两个不同类型的调节型水库,通过对比它们的水温实测资料和水温模型模拟结果,分析了不同类型水库对水温的影响特征。研究表明,对多年调节水库而言,在枯水年高水位时,汛期库区垂向水温呈稳定的3层分布,底层水温变幅较小,受水库调节,下泄水体水温过程相比天然河道坦化作用明显,彻底改变了天然水温季节性高低分明的正弦分布规律;在平水年低水位时,非汛期水库垂向水温分布为混合型分布,汛期为两分层分布,底部没有恒温层,下泄水体对河道水温影响较小;丰水年中水位运行对水温的影响介于前两者之间;对于年调节水库而言,在丰水年和平水年对水温的影响基本一致,而在枯水年升温期下泄水体升温与前两者相比明显滞后。因此,应关注不同类型水库运行方式对水温的影响差异,通过设置合理的水库运行方式可以避免对下泄低温水的负面影响。

The operation mode of reservoir is one of the factors that can be controlled by human, and it will cause hydrology and heat changes in the river. The water temperature characteristics of different operation methods were analyzed based on the measured data and simulation results by taking two different types of regulation reservoirs as an example. The result indicated that when multi-year regulating reservoir running on a high-water level in the flood season of the dry year, there would be a stable three-layer of vertical water temperature phenomenon and small changes on the bottom cryosphere, also an obviously flat phenomenon of the discharged water temperature thoroughly changed the sine distribution rule of natural water varying with the season. The vertical temperature of reservoir was mixed distribution in the dry season and dual stratifica tion distribution in the flood season without cryosphere in bottom when the reservoir running on a lower water level in the average year. Meanwhile, the discharged water had little impact on the down-stream river water temperature. Moreover, the effects on water temperature are between the former two while the reser- voir running on a middle-water level of the flood year. As to the multi-year regulating reservoir, there were little differences on water temperature distribution in the flood year or the average year, but an obviously de- lay of the discharged water temperature in the warming up time of the dry year. Therefore, different opera- tion modes should he taken into consideration and the negative effect of cold water can be avoided by setting the reservoir on an appropriate operation mode.