升钟水库和灌渠水温观测分析及分层取水效果研究

Change of Temperature in Shengzhong Reservoir and Its Irrigation Canal and Feasibility Analysis of Stratifyingly Taking Water from the Reservoir

【目的】水库升温期泄放低温水灌溉是大中型水利工程普遍面临的环境问题,探讨西南山区大型水库和灌渠热状况的时空演变规律以及水库分层取水措施对下泄低温水的改善效果。【方法】2012年5月对升钟水库库区和灌渠水温进行现场观测并分析了其变化机理。【结果】库表水温达到23.3℃,表层温跃层厚15 m,温度梯度达到0.93℃/m,距库表15 m深以下均维持9.3~9.8℃的低温;库区水体流动弱,主库及支库同高程水温基本相同;采用分层取水措施后,渠首取水水温为18.0℃,较暗渠对应高范围内程平均水温高8.0℃;干渠沿程增温幅度为0.8℃/100 km,支渠、斗渠的增温效率大于干渠。【结论】升钟水库调节性能强,受气象条件影响,库区水温分层明显,分层取水效果显著,单宽流量是渠系沿程增温率的主要影响因素,同时支渠和斗渠的增温效果不可忽略。

【Objective】Low temperature in reservoir water taken for irrigation is an environmental issue facing large and medium-size hydraulic engineering projects during temperature rising period. The objective of this paper is to analyze the spatiotemporal temperature change in reservoir and irrigation canal, as well as the feasibility of stratifingly taking water from the reservoir.【Method】We measured and analyzed the water temperature in Shengzhong reservoir and one of its canals in May 2012.【Result】The surface water temperature in the reservoir was 23.3℃ with the thermocline at the depth of 15 m, below which the temperature remained within 9.3 to9.8 ℃. The water flow in the reservoir was weak, and at the same altitude, the temperature in the main reservoir and its branches was approximately the same. The water temperature measured at the head of the canal was18.0 ℃, 8.0 ℃ higher than the culvert average temperature. The increase in temperature downward the main canal was 0.8 ℃/100 km and the increase in the temperature downward along the branch and lateral canals was faster than that in the main canal.【Conclusion】The self-regulation in Shengzhong reservoir was strong. Impacted by meteorological change, there was a noticeable temperature stratification in the reservoir. It is hence feasible to stratifingly take water from it. The flow rate was the main factor affecting the temperature rise along the canal, although the impact of the branch and lateral canals cannot be overlooked.