Sufficient water is essential for maintaining rice production yields, but precipitation and ground water generally do not meet the requirements for rice growth. Irrigation is therefore necessary and the quantity of irrigation water requirement (IWR) is also highly dependent on climatic alterations. We utilized an ensemble of 20 fine-resolution downscaled global climate models to characterize the future dynamics of IWR across Northeast China, under two representative concentration pathway scenarios (RCP4.5 and RCP8.5). Crop evapotranspiration was a critical factor in IWR determinations and was estimated through the Hargreaves model. The model was recalibrated to optimize its performance and this resulted in normalized root mean squared errors of < 10%. Based on reliable crop evapotranspiration and effective precipitation data in baseline (1976–2005) and future periods (2036–2065 and 2070–2099), IWR decreased from southwestern Heilongjiang and western Jilin to the southeastern and northeastern areas. The IWR displayed a general increasing trend but overall the tendency decreased from west to east. The western areas were exposed to higher magnitudes of IWR increases, indicating that the water deficit for rice would be more severe in these regions. IWR levels increased with time slice under RCP8.5 relative to RCP4.5. The predicted IWR changes in future periods were greatest for Heilongjiang, followed by Jilin and Liaoning. In addition, Heilongjiang was predicted to have the most stable IWR in the future. These predictions of IWR dynamics highlight sensitive areas prone to water deficits and can serve as guides for specific irrigation schedules in the different rice growing regions across Northeast China.

充足的水对于维持稻米的产量至关重要，但是降水和地下水通常不能满足稻米生长的要求。因此，灌溉是必要的，灌溉水需求量（IWR）也高度依赖于气候变化。在两个代表性的集中路径情景（RCP4.5和RCP8.5）下，我们利用20个高分辨率的按比例缩小的全球气候模型的集合来表征了东北地区内河水的未来动态。作物蒸散量是IWR测定中的关键因素，可通过Hargreaves模型进行估算。重新校准模型以优化其性能，这导致<10％的归一化均方根误差。基于基线（1976–2005）和未来时期（2036–2065和2070–2099）的可靠作物蒸散量和有效降水数据，IWR从黑龙江西南部和吉林西部到东南部和东北部减少。IWR呈总体上升趋势，但总体趋势从西向东下降。西部地区的IWR增加幅度更大，表明这些地区的水稻缺水现象将更加严重。在RCP8.5下，相对于RCP4.5，IWR水平随时间片增加。黑龙江省未来的IWR变化预测最大，其次是吉林和辽宁。此外，预计黑龙江省的IWR将来会最稳定。