水电开发对大渡河瀑布沟以下河段的水温影响

Influence of hydroelectric development on water temperature downstream the Pubugou hydropower station of the Dadu River

为探究水电开发对大渡河水温过程的影响,采用原型观测和数学模型相结合的方法,对比分析了瀑布沟电站开发前后下游河道的水温时空变化特性。研究成果表明,与天然情况相比,现阶段瀑布沟下游沿程水温出现了明显的均化效应和延迟效应以及春夏季低温水、秋冬季高温水现象,最大降温2.4℃出现在4月的龚嘴尾水断面,最大升温3.3℃出现在12月的瀑布沟尾水断面;瀑布沟下游小型水库均未出现水温分层现象,但形成的蓄水体对沿程升温有一定的弱化,沿程增温率由天然状态的0.8℃/100 km降至现阶段的0.5℃/100 km;采用考虑了机械能转化的数学模型能较好地模拟瀑布沟下游河道的水温过程,率定得到的"机械能—内能"转化率为55%。

To research the influence of hydroelectric development on water temperature of the Dadu River,a comparative analysis was done to describe the characteristics of temporal and spatial water temperature changes downstream river reach after and before completion of the Pubugou hydropower station by means of prototype observation and numerical simulation. The study showed that compared with natural condition,the current water temperature downstream the Pubugou reach had clear features of both averaging and delayed effects,as well as the phenomena of low temperature water in spring and summer and high temperature water in autumn and winter with the biggest drop of 2. 4 ℃ at Gongzui tailrace in April and the biggest rise of 3. 3 ℃ at Pubugou tailrace in December. The temperature stratification didn＇t occur in small lower reservoirs downstream the Pubugou reach,but the reservoir water weakened the water temperature rising along the reach. The water temperature process downstream the Pubugou reach was simulated well by the model that took the mechanical energy conversion into consideration,and the conversion rate of ＂mechanical energy and internal energy＂came to 55% after calibration.