Study on the Impact of Water Temperature of a Large Reservoir and Its Irrigation Area in Yunnan Province

A large reservoir in Yunnan is a seasonal regulation reservoir. The distribution of reservoir water temperature and the discharge water temperature and the water temperature along the main irrigation canal in typical normal year were analyzed and predicted using the vertical two-dimensional water temperature mathematical model with average width. The water temperature structure of the reservoir presented transitional water temperature structure and seasonal water temperature stratification phenomenon. The surface thermocline existed from February to May,and the stratification phenomenon was obvious. The maximum vertical temperature difference was 3. 3℃. The operation of the reservoir has a certain impact on the downstream water temperature process,such as low-temperature water in spring and summer. The maximum temperature drop is 2. 3℃ and the average annual discharge water temperature is 0. 2℃,which is lower than the time before the dam was constructed. The analysis showed that the irrigation water temperature in each growth stage of rice was within the normal water temperature range,and the normal growth of rice has not been affected. The research results would provide technical reference for related environmental management.