南水北调中线工程总干渠冬季大流量输水水温调控措施

Control measures of water temperature of the Middle Route of South-to-North Water Transfers Project main channel with large discharge in winter

为保障南水北调中线工程冬季输水安全,利用建立的总干渠全线一维水温模型,针对350、280、210和150 m3/s这4种不同输水流量方案,模拟分析各方案在强冷冬、冷冬、平冬和暖冬等典型冬季气象条件下总干渠冬季输水保温效果,在此基础上提出总干渠冬季无冰盖大流量输水水温调控措施。结果表明:针对不同典型冬季气象条件,在有限条件下采取无冰盖大流量输水调度运行方式,可不同程度缩短输水流动时长、减少沿程水体热量损失,从而达到保温效果;在各典型冬季年份气象条件下,随着总干渠输水流量增大,沿程水温比降相应减缓,明渠末端水温相应提升;在冬季气象条件适宜情况下,总干渠冬季采取无冰盖大流量输水水温调控措施,既有利于减小水温降幅,同时也可有效解决冬季输水能力受限问题;建议根据总干渠中短期气温预报和水温预测情况,在冷冬、平冬和暖冬等典型冬季气象条件下尽可能采取较大输水流量输水模式,在强冷冬气象条件下可分时段、分渠段采用无冰盖大流量输水模式。

On the premise of ensuring the safety of water delivery in winter,it is an important measure to adopt nonice-covered large discharge water delivery mode to enhance the main canal water conveyance capacity of the Southto-North Water Transfers Project in winter,the thermal insulation of canal water conveyance is one of the key technical bottlenecks to ensure the operation of non-ice-covered water conveyance of main canal.Based on the analysis of the water temperature and ice condition in the 8 winters since the water supply of the whole line under the current regulation of the Middle Route project,the operation method of non-ice-covered largeflow water conveyance is put forward to realize water conveyance and heat preservation in winter,aiming at four kinds of dispatching operation schemes of different water flow,such as 350,280,210 and 150 m3/s,simulation analysis of each scheme of water transfer in strong cold winter,cold winter,flat winter and warm winter weather conditions such as the winter heat preservation effect of the main canal.On this basis,a proposal for optimal operation of non-ice-covered water conveyance and thermal insulation of main canal in winter is proposed.The results of numerical simulation show that:according to different typical winter weather conditions,the nonice-covered large-flow water transfer operation mode is adopted under limited conditions,it can shorten the flow time of water conveyance and reduce the heat loss of water body,thus achieving the effect of heat preservation,the water temperature at the end of the open channel is also higher than that at the end of the open channel,at the same time,it can also effectively solve the problem of limited water conveyance capacity in winter.Based on the short-term air temperature forecast and water temperature forecast in the main canal,it is suggested that water transfer operation mode with larger water discharge should be adopted as far as possible under the typical winter weather conditions such as cold winter,flat winter and warm winter,and under the strong cold winter weather conditions,non-ice-cap large flow water conveyance model can be used in time and channel sections.