糯扎渡水电站不同调度下下泄低温水改善效果研究

Research on the improvement effect of low outflow temperature under different reservoir operation at Nuozhadu Hydropower Station

【目的】大型水库下泄低温水影响及相应的减缓措施效果受到水库运行、取水方式等因素的影响,各因素之间彼此联系、相互作用。明晰水库运行方式对下泄水温的影响及其对叠梁门分层取水改善效果,可为大型水库的叠梁门分层取水效果评估及优化调度提供参考。【方法】以糯扎渡水电站为研究对象,建立糯扎渡立面二维水温数学模型,探讨水库运行方式对下泄水温及叠梁门分层取水效果的影响。【结果】结果显示:(1)水库修建后下泄水体存在明显的冬季高温水、夏季低温水现象,单独运行时,10月—次年2月水温较天然水温平均偏高2.0℃,4—6月偏低2.9℃。(2)与单独运行相比,糯扎渡水电站在梯级联合运行下的下泄水体升温效应更强,10月—次年2月水温平均升高2.5℃,3—8月水温平均升高1.4℃。(3)使用叠梁门后,4—8月下泄水温较单层取水时平均提高1.9℃,水温达到18℃的时间平均提前78 d。【结论】结果表明:澜沧江下游梯级联合运行对高温水产生叠加影响,对低温水表现出削弱影响;叠梁门抬高了取水流动层位置,对下泄水温有较好的改善作用,其改善效果与淹没水深、运行时段有明显的关系。

[Objective]The impact of low outflow temperature from large reservoirs and the effects of corresponding mitigation measures are affected by factors such as reservoir operation and water intake method,and all factors are connected and interact with each other.Clarifying the influence of the operation mode of the reservoir on the outflow temperature and the improvement effect on the selective condition of the stop log gate can provide a reference for the evaluation and optimal scheduling of the strati-fied water intake effect of the stop log gate in large reservoirs.[Methods]Taking the Nuozhadu Reservoir as the research object,a two-dimensional water temperature mathematical model of the Nuozhadu facade was established,and the influence of the reser-voir operation mode on the outflow temperature and the layered water intake effect of the stop log gate was discussed.[Results]The result showed that:(1)after the construction of the reservoir,there were obvious phenomena of high outflow temperature in winter and low outflow temperature in summer.When operating alone,the outflow temperature from October to February of the next year was 2.0℃higher than the natural water temperature on average,and from April to June is 2.9℃lower.(2)Compared with the single operation,the Nuozhadu hydropower station under the joint operation of cascades has a stronger heating effect of outflow,with an average increase of 2.5℃in outflow temperature from October to February of the following year,and an average increase of 1.4℃in March to August.(3)The application of the stop log gate raised the inflow layer,which had a good effect on improving the low outflow temperature.The average outflow temperature increased by 1.9℃from April to August compared to nonselective condition,and the time when the outflow temperature reaches 18℃is 78 days earlier on average.[Conclusion]The result show that the joint operation of cascades in the lower reaches of the Lancang River has a superimposed effect on high outflow temperature,and a weakening effect on low outflow temperature.The application of the stop log gate raised the inflow layer,which had a good effect on improving the low outflow temperature,and its improvement effect has a significant relationship with the submerged water depth and operating period.