基于水足迹的中国农业用水效果评价

为兼顾灌溉用水效率和总量控制评估区域农业用水效率，结合水足迹与灌溉发展状况构建了农业用水效果评价指标（agricultural water use effect，AWE），AWE越小农业用水效果越好。在核算2000-2014年间31个省区农作物水足迹的基础上，分析了中国AWE的时空格局及其与灌溉用水效率指标之间的关系。结果显示：中国年均农作物水足迹为1.097 2×1012 m3，蓝水、绿水足迹分别占13.1%和86.7%，且均随时间增加；单位耕地面积农作物水足迹及绿水比例均呈现由东南向西北递减，研究时段内灌溉效率稳步提升，而由于灌溉用水规模的扩大和蓝水足迹比例的增长，AWE由2003年的0.113增长到2014年的0.137，中国农业用水效果呈恶化趋势；AWE空间差异大，且在不同年份均表现为黄淮海平原和西部省区较大而东南沿海较小；经济发达地区农业用水效果有明显改善趋势，而粮食增产任务加大的黑龙江省AWE的增速最大；AWE与传统灌溉用水效率评价指标无空间一致性，灌溉效率和水分生产率高的北方农业主产区应注重农业生产用水效果的评估与提升。农业用水效果评价可为区域灌溉用水效率提升与总量控制的科学研究与决策实践依据。

Assessing agricultural water use effect of China based on water footprint framework

Abstract: Efficient utilization of agricultural water resources contributes to regional food, water and ecological security. The aim of this paper is to evaluate agricultural water use efficiency taking into account both efficiency improvement and total input control in agricultural production. In view of the study of irrigation water efficiency and total input control, the agricultural water use effect (AWE) index was established based on water footprint and irrigation development framework. For a selected region, the smaller AWE means the better agricultural water use effect. The temporal and spatial pattern of AWE in China during 2000-2014 and its relationship with traditional irrigation water efficiency indices were analyzed based on the calculation of regional agricultural water footprint (AWF), irrigation efficiency (IE) and irrigated land proportion of arable land (IPA) in 31 provinces, municipalities and autonomous regions of China. The results showed that the average annual AWF in China was estimated to be 1.097 2×1012 m3 in the observed period, and the proportions of blue and green water footprints were 13.1% and 86.7% respectively. Both the blue and green water footprint increased over time due to the expansion of agricultural production scale. The spatial difference of AWF and its composition were large, and both the water footprint per unit cultivated area and green water proportion decreased from the southeast to the northwest in China. All of the national IE, irrigation water use and blue water proportion in AWF as a whole improved over time in the latest 15 years. Meanwhile, national AWE value increased from 0.113 in 2003 to 0.137 in 2014, indicating that the agricultural water use situation of China was deteriorating. The space difference of AWE was large and maintained stable in each year of the study period. High AWE values were found in the Huang-Huai-Hai Plain and the Western China, and the low values existed in the southeastern coastal areas of the country. The AWE in the economically developed areas was improved obviously, and the maximum growth rate of AWE occurred in Heilongjiang, which was about 7.81% per year. We also found that there was no spatial consistency between AWE and traditional irrigation water use efficiency evaluation indicators, such as IE and irrigation water productivity. The northern agricultural main producing areas with high irrigation efficiency and irrigation water productivity should pay attention to the assessment of irrigation water utilization and enhance the agricultural water use effect. Only the index AWE can be used for the agricultural water use efficiency considering both efficiency improvement and total input control assessment in current study. The evaluation of AWE can be used as a basis for scientific research and decision-making on efficiency improvement and total quantity control of regional irrigation water resources.