基于输水损失动态变化特性的渠系优化配水模型研究

渠系优化配水是灌区减少渠道渗漏损失、提高渠系水利用效率的重要节水管理措施,但当前渠系优化配水模型的渗漏损失计算方法难以真实反映渠床土壤透水性随时间动态变化的特征,导致人为的配水偏多或者偏少。鉴于此,本文探索性引入渠床土壤前期影响含水量的概念来描述渠床土壤湿润程度在渠道输配水过程中的动态变化,提出了一种新的渠道输水渗漏损失动态计算方法,在此基础上建立了一种渠床湿润状况无后效性特征的渠系优化配水模型。河套灌区骨干渠系2012年夏灌优化配水实例研究表明:与传统基于考斯加科夫公式的优化配水方式相比,新配水模型在配水初期加快了配水进程,缩短了渠床土壤自由渗漏持续时间,从而使渠床土壤尽快达到了湿润状态,而在配水末期则延缓了配水进程。配水结果显示:在不增加总干渠引水量的情况下减少渗漏损失水量1560万m~3,渠道水利用效率提高1%。本文提出的渠系优化配水模型是针对渠床土壤湿润状况的动态变化进行流量过程的调控,可用于指导灌区渠系科学合理配水与集中统一调度。

Study on optimal water distribution of canal system based on dynamic change characteristics of water conveyance losses

Optimal water distribution of canal system is an important water-saving management measure to reduce the leakage loss and improve the water use efficiency of the canal system. However,the current calculation method of leakage loss of the optimized water distribution model is difficult to reflect the dynamic change characteristics of the soil permeability of the canal bed over time, resulting in more or less artificial water distribution. In view of this,this paper introduces the concept of pre-effect water content of canal-bed soil to describe the dynamic change of soil moisture in canal bed in the process of water transmission,and then puts forward a new dynamic calculation method for water leakage loss of canal bed. On this basis, an optimal water distribution model with no aftereffect is established. The case study on the optimal water distribution for summer irrigation in 2012 of general main canal system of Hetao Irrigation District shows that:compared with the traditional optimal water distribution mode based on Kostiakov formula, the new model accelerates the water distribution process in the initial stage of water distribution, makes the soil in the canal bed reach the moist state as soon as possible,shortens the duration of soil free seepage, and delays the water distribution process at the end of water distribution. Without increasing the total amount of water diverted from the general main canal,15.6 million m³ of water loss is reduced and the water use efficiency of the canal is increased by 1%. The discovery of this law has important guiding value for scientific and rational water distribution and centralized and unified operation of irrigation canal system.