向家坝灌区水温改善措施效果研究

水温是影响灌区农作物灌溉效果的重要因素。为明确特定水库取水口低温水对灌区灌溉的影响程度及多种低温水减缓措施的改善增温效果,以向家坝灌区北总干渠一期工程为研究对象,采用纵向一维水温数学模型,定量分析并研究低温水减缓措施对灌区水温的改善效果。结果表明:与向家坝坝址处的天然水温相比,单库运行时(建坝近期)向家坝灌区部分渠道最大降幅可达2.1℃,梯级电站联合运行后(建坝远期)最大降幅可达3.1℃,建坝远期的低温水效应大于近期运行时的低温水效应。距取水口最近的柏溪斗渠4月灌溉水温降幅可达3.1℃,而较远处的两木斗渠4月份灌溉水温降幅为1.3℃,灌溉水温的降幅随灌渠离取水口距离的增加而减小,向家坝北总干渠前38 km低温水效应较显著, 38 km以外渠道受低温水影响较小。取水口设置叠梁门分层取水措施与灌区设置晒水池增温措施具有相近的增温效果,4月增温效果约为0.4℃～0.9℃。采用已建塘坝、窖池等小水利设施辅助晒水池进行晒水增温对低温水具有显著的改善效果,4月增温幅度约为1.3℃～1.7℃。研究成果可为湖库管理部门制定近期及远期运行方案提供决策依据。

Study on the Effect of Water Temperature Improvement Measures in Xiangjiaba Irrigation Area

Abstract：Water temperature is an important factor affecting the effect of crop irrigation. In order to clarify the effect of low-temperature water at the intake of a specific reservoir on irrigation and the effect of various low-temperature water mitigation measures in the irrigation area, taking the first phase of the North Main Canal of Xiangjiaba Irrigation Area as the research object, quantitatively analyze the effect of low-temperature water mitigation measures in the irrigation area. The results show that compared with the natural water temperature of the dam site, the maximum decrease of water temperature in irrigation area can reach 2.1℃ during the operation of single reservoir (in the near future), and it can reach 3.1℃ after combined operation of cascade power stations (in the long term). The long-term low-temperature water effect of the dam construction is greater than that of the near future. The irrigation water temperature of nearest ditch (Baixi Ditch) decreases by 3.1℃ in April, while that of the far ditch (Liangmu Ditch) decreases by 1.3℃.The farther the irrigation canal is from the intake, the smaller the decrease of irrigation water temperature, the effect of low-temperature water in front of 38 km of the main canal in the north of Xiangjiaba is significant, while less effects beyond 38 km. The temperature increase effect of stoplog gate is similar to that of sunning water pool, the temperature increase effect is about 0.4 ~0.9℃ in April. Using existing water conservancy facilities such as ponds, pits to supplement the sunning water pools to increase the temperature of low-temperature water has a significant improvement effect, the range of temperature increase in April is about 1.3-1.7℃. The research results can provide decision-making basis for the management departments of lake and reservoir to make short-term and long-term operation plans.