基于作物生产水足迹的陕西省水资源压力评价

Assessment of water stress in Shaanxi Province based on crop water footprint

  • 摘要: 作物生产水足迹可以反映农业生产过程中的水资源利用效率及其真实占用量, 对作物生产水足迹的量化可为各地区明确农业生产过程的用水情况, 根据当地水资源禀赋合理调整农业种植结构, 提高用水效率提供理论支撑。以陕西省为研究区域, 在构建了考虑渠系水面蒸发损失的水足迹量化方法的基础上, 对陕西省主要作物生产水足迹(WFP)进行量化, 并构建了反映水足迹与区域水资源关系的水资源压力指数(βt)和蓝水资源压力指数(βb), 分析了陕西省2000-2012年作物生产水足迹与水资源压力指数的时空分异特征。结果显示: 作物生产水足迹在作物间、区域间均有较大差异, 且在研究时段内均呈现下降趋势, 全省综合作物生产水足迹由1.382 m3·kg-1减小到0.931 m3·kg-1; 全省年均作物水足迹总量为127.39×108 m3, 绿水比例为50.22%; 陕西省βtβb多年均值分别为0.255、0.187, 渭南市、咸阳市两地βtβb分别为0.610和1.200左右, 是水资源压力最为严重的地区; 除陕南地区外, 陕西省其他区域均面临着水资源不可持续的挑战。

     

    Abstract: Water footprint, proposed by professor Hoekstra, is a new indicator of water consumption, which includes both direct and indirect water use. Water footprint of crop production is the volume of water consumed in producing per kilogram of crop. It not only reflects water use efficiency, but also the real water occupation in the process of agricultural production. This paper calculated both green and blue water footprints of crop production. For crop production, green water footprint reflects how much green water is consumed by producing per kilogram of crop, and blue water footprint is water consumed from sources such as surface water or groundwater. Quantification of crop water footprint will contribute to our knowledge of determining water utilization conditions in agricultural production and provide theoretical basis for improving water use efficiency by optimizing cropping patterns in relation to local water resources endowment. Using Shaanxi Province as the study area, this paper calculated water footprint of crop production (WFP) using a modified method that took into account water evaporation loss during transmission and distribution processes of water in crop fields. The paper then used the (blue) water stress indexes βt (βb) to determine the relationship between water resources and total/blue water footprints. Finally, the temporal and spatial distributions of WFP,βt and βb in Shaanxi Province were analyzed. The results showed large differences in WFP among crops and crop production areas, with a general declining trend in WFP. Water footprint of integrated crop production (IWFP) in Shaanxi Province dropped from 1.132 m3·kg-1 to 0.931 m3·kg-1 from 2000 to 2012. While Xi'an City had the lowest average IWFP (0.849 m3·kg-1), Yulin City had the highest one (1.730 m3·kg-1). The average annual total crop water footprint (WF) of Shaanxi Province was 127.39×108 m3, with green water footprint (GWF) proportion of 50.22%. With similar spatial distribution characteristics of water footprint of crop production, crop water footprint varied significantly from 3.47×108 m3 in Tongchuan City to 24.19×108 m3 in Weinan City. The multi-year averages of βt and βb in Shaanxi Province were 0.255 and 0.187, respectively. Also βt and βb values for Weinan City and Xianyang City were 0.610 and 1.200, respectively. Weinan City and Xianyang City had the most severe water scarcity in Shaanxi Province. Apart from the southern area of Shaanxi Province, water unsustainable development challenges were noted in each of the districts in Shaanxi Province.

     

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