Abstract Efficiency is one of the most important assessment indicators in irrigation systems. Classical efficiency (CE) is not an exact index due to the lack of consideration of the return flows. Therefore, the neoclassical concepts of the efficiency are considered to take a part of losses of irrigation water as a return flow into account. Quality of the return flows may change in their path and it must be considered in evaluating the efficiency and productivity of irrigation water. This research was carried out to investigate this challenge. Sustainable efficiency (SE) was applied based on the water balance and quality of return flows. The methodology and detail for computing different parameters and their quality and beneficial coefficients in water balance equation were presented. Moghan irrigation and drainage network in the northwest of Iran was selected as the study area and CE and SE were calculated in meso and micro levels using the meteorological data, cropping pattern, irrigation water volume, natural and artificial drainages, infiltration and return flow quality. In addition, the irrigation water productivity was calculated by considering the volume of water based on the different concepts of efficiency. Quality coefficient related to return flow had different values in different months (0.85 in August and 1 in November and December). The results showed that about 87 % of inflow, 91 % of the rainfall, 89 % of the evapotranspiration, 13 % of the non-reusable water, and 91 % of the return flow were useful in the study area. The highest and the lowest efficiencies are occurred in September and November, respectively. The average of meso and micro Sefficiencies were 72 % and 47.5 %, respectively, and the CE was 37.9 %. The results showed that water productivity based on the SE is more than that of the CE. The water productivity at the meso level also showed a higher value than at the micro level.

中文翻译：

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考虑回流质量的基于水平衡的灌溉水效率和生产力

摘要 效率是灌溉系统最重要的评价指标之一。由于缺乏对回流的考虑，经典效率 (CE) 不是一个精确的指标。因此，新古典主义的效率概念被认为是将部分灌溉水损失作为回流考虑在内。回流的质量可能会在其路径上发生变化，在评估灌溉水的效率和生产力时必须考虑到这一点。进行这项研究是为了调查这一挑战。基于水平衡和回流质量应用可持续效率 (SE)。介绍了计算水平衡方程中不同参数及其质量和有益系数的方法和细节。选择伊朗西北部的莫干排灌网络作为研究区域，并利用气象数据、种植模式、灌溉水量、自然和人工排水、入渗和回流质量在中观和微观水平计算CE和SE。此外，根据不同的效率概念，通过考虑水量来计算灌溉水生产力。与回流相关的质量系数在不同月份有不同的值（8 月为 0.85，11 月和 12 月为 1）。结果表明，大约 87% 的流入量、91% 的降雨量、89% 的蒸散量、13% 的不可重复使用的水和 91% 的回流水在研究区是有用的。最高和最低效率分别出现在 9 月和 11 月。细观和微观效率的平均值分别为 72% 和 47.5%，CE 为 37.9%。结果表明，基于 SE 的水生产率高于 CE。中观水平的水生产力也显示出高于微观水平的值。