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a b s t r a c tIt is very important for regional agricultural sustainable development by researching the relationship between water consumption and yield, determining the reasonable irrigation threshold and proposing the optimal irrigation schedule. The Aquacrop model was verified by the measured data, and then, the variations of water consumption, yield, and water productivity for winter wheat under various irrigation schedules in North China Plain were analyzed by this model. Meanwhile, the irrigation thresholds under the highest yield and the highest water productivity were determined. Finally, the optimal irrigation schedules for the winter wheat were proposed after taking irrigation water use productivity (IWP) and water consumption productivity (WP) as the objective, respectively. The results show that (1) the determination coefficient (R2) > 0.747 between the simulated and observed values of the soil water content and canopy cover, and the Nash efficiency coefficient (EF) > 0.482, and R2 > 0.865 between the simulated and observed values of the biomass and yield, and EF > 0.864, so the model can simulate the soil water content, canopy cover, crop biomass, and final yield accurately.(2) When irrigation amount ranged from 150 to 400 mm, the water consumption increased along with the increase in irrigation amount. When the irrigation amount reached 400 mm, the water consumption remained unchanged. (3) When the irrigation amount ranged from 150 to 300 mm, the yield and WP increased with the increase in irrigation amount, and the increasing trend of the yield and the WP slowed down and even reduced when the irrigation amount exceeded 300 mm. (4) Optimization of irrigation schedule in various hydrological years shows that after taking the maximal IWP as the objective, the yield reached 3,821-5,959 kg hm -2 with the irrigation frequency of two times, and the optimal irrigation amount of 140-220 mm. After taking the maximum WP as the objective, the yield reached 6,727-6,926 kg hm -2 with irrigation frequency of three times, and the irrigation amount of 240-330 mm. For the areas with the shortage of water resource such as North China Plain, this study may provide theoretical basis for irrigation water management of winter wheat.

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The construction of ecological irrigation districts is of great significance to protect the Yellow River ecology and achieve sustainable development of the local ecological economy. Taking the ecological irrigation district of Helan County as the study area, a health evaluation index system of the irrigation district was established, including three primary indexes of ecological environment, modernization level, and agricultural production and benefit, and 20 secondary indexes. Then, the Topsis method, entropy weight evaluation method, fuzzy pattern recognition model, and variable fuzzy model were used to evaluate the health of the Helan ecological irrigation district. In order to avoid the one-sidedness of the evaluation results of a single evaluation method, a combined evaluation method named deviation maximization combined evaluation method was used to combine each single evaluation result. The evaluation results by the combined evaluation method showed the following: (1) The ecological health of Helan irrigation district had a trend of becoming better from 2007 to 2016. (2) The grey correlation analysis showed that the soil salt content, groundwater depth, canal lining rate, ratio of efficient water-saving irrigation area, information level of the irrigation district, water productivity, agricultural unilateral aquatic output value, irrigation water consumption per mu, and coefficient of effective utilization of farmland irrigation water were closely related to the evaluation results. (3) In order to effectively improve the ecological health of Helan irrigation districts, it is necessary to reduce soil salt content and groundwater salinity, increase canal linings, promote water-saving irrigation measures, and agricultural information construction, etc.

Irrigation is facing increasing pressure from other competitive water users to reduce water consumption in a water scarce region. Based on the Basin-wide Holistic Integrated Water Assessment (BHIWA) model, the effects of water management strategies on water balance in the dry regions of North China were analyzed. The results show that, with the decrease of irrigation water supply reliability (IWSR) and the increase of irrigation water use efficiency (WUE), irrigation water use decreased significantly, leading to reduced agriculture water consumption, and sustained ground water levels. Compared with the increase of WUE, the decrease of IWSR contributes more to reducing irrigation water consumption and protecting groundwater. Sensitivity tests show that among various water cycle components, irrigation water use is most sensitive to changes, followed by agriculture water consumption, and then groundwater level. Reducing IWSR is an effective strategy to reduce irrigation water consumption and promote sustainable water resources management, which could be the support of basic data and theory for regional water resources planning.