Faculty of Geography, Philipps-Universität Marburg, Marburg 35032, Germany.
School of Geographical Sciences, Southwest University, Chongqing 400715, China; Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Sci Total Environ. 2020 Oct 10;738:139502. doi: 10.1016/j.scitotenv.2020.139502. Epub 2020 May 19.
The notion of water footprint provides a novel perspective for understanding the relationship between physical water and virtual water, especially in agricultural production. In this study, with the help of CROPWAT 8.0 model, we estimate the water footprint requirement (WFr) of main crops growth for 2005, 2010 and 2015 in Zhangjiakou City, an extreme water shortage region in northern China, and three new indicators are introduced, i.e., green water footprint occupancy rate (GWFor), blue water footprint deficit (BWFd), and virtual water consumption per output value (VWV). The results indicate that the total WFr increased from 1.671 billion m to 1.852 billion m during the study period, of which the green water was always about twice as the blue water. Cereals, as the main staple food, had the largest WFr, while the WFr of potatoes increased the fastest, which was the result of large-scale promotion of potato cultivation in recent years. The spatial characteristics of the GWFor and BWFd are closely related to altitude, that is, the GWFor was less than 50% in higher-altitude Bashang area, while it was more than 50% in lower-altitude Baxia area, and the BWFd was generally smaller in Bashang area than in Baxia area. Due to differences in crop types and food prices, higher water footprint food productivity does not absolutely mean higher water footprint economic productivity. Therefore, it is vital to consider from two perspectives (food yields priority or economic benefits priority) to formulate a reasonable water footprint utilization policy. This study is expected to broaden the investigation of crop water footprint and make a contribution to sustainable agricultural water management.
水足迹概念为理解自然水和虚拟水之间的关系提供了一个新视角，尤其是在农业生产方面。本研究借助 CROPWAT 8.0 模型，估算了 2005、2010 和 2015 年中国北方极度缺水地区张家口市主要作物生长的水足迹需求（WFr），并引入了 3 个新指标，即绿水足迹占有率（GWFor）、蓝水足迹亏缺（BWFd）和单位产值虚拟水消耗量（VWV）。结果表明，研究期间 WFr 从 16.71 亿立方米增加到 18.52 亿立方米，其中绿水始终约为蓝水的两倍。作为主要主食的谷物具有最大的 WFr，而土豆的 WFr 增长最快，这是近年来大规模推广土豆种植的结果。GWFor 和 BWFd 的空间特征与海拔密切相关，即海拔较高的坝上地区的 GWFor 小于 50%，而海拔较低的坝下地区的 GWFor 大于 50%，且 BWFd 一般在坝上地区小于坝下地区。由于作物类型和食品价格的差异，较高的水足迹粮食生产力并不绝对意味着较高的水足迹经济生产力。因此，从优先考虑粮食产量或经济利益两个角度制定合理的水足迹利用政策至关重要。本研究有望拓宽对作物水足迹的研究，并为可持续农业水资源管理做出贡献。
