粮食供需平衡视角下虚拟水研究——以陕西省商洛市为例

Study on Virtual Water in Grain at a Perspective of the Balance between Supply and Demand-A case in Shangluo City of Shaanxi Province

本文基于虚拟水理论与方法，对陕西省商洛市1990~2012年主要粮食作物的虚拟水含量和虚拟水总量进行了计算，并应用经验模态分解法（EMD）对粮食产量和虚拟水总量波动进行多时间尺度分析，以确定影响虚拟水总量中短期波动的最主要因素。从粮食需求量和粮食供给量两个方面对未来商洛市虚拟水消耗量进行预测与分析。研究结果表明：（1）从虚拟水的角度来看，玉米的节水效率最高，大豆和小麦次之，油菜的节水效率最低；（2）全生育期小麦的虚拟含量水最高，其次为玉米和大豆，油菜的虚拟水含量最少，且虚拟水总量的年际变化情况与各作物虚拟水总量波动趋势大致相同；（3）从EMD分析结果来看，粮食产量的中短期波动是影响虚拟水含量变化的主要控制因素；（4）基于满足当地人类发展的粮食需求量，2030年虚拟水总量将占当地水资源总量的18.92%，若基于粮食供给量的虚拟水总量2030年仅为10.87%，仍需调入的虚拟水总量将达到当地水资源总量的8.05%；（5）商洛市水资源充沛，但粮食自给率不高，仍需从其他地区调入含大量虚拟水的粮食作物来满足自身发展的需要，从虚拟水的角度来看，商洛市可以通过调整农作物的种植结构和粮食的调入结构来减少对虚拟水的调入。

Virtual and total amount of virtual water content of main grain crops in Shangluo City of Shaanxi Province during 1990-2012 were calculated with the theory and the method of virtual water. With the empirical mode decomposition method,the grain yield and total fluctuation of virtual water between 1990 and 2012 in Shangluo were analyzed in terms of multiple time scales and grain yield was concluded as the main factor of the short-term fluctuation of total virtual water. The future consumption of virtual water was forecasted and analyzed from two aspects of grain demand and supply in Shangluo City.The results showed that: (1) from the perspective of virtual water, the water-saving efficiency of crops in Shangluo in descending order were corn, soybean, wheat and rape; (2) the highest virtual water content during the whole growth period was wheat, followed by corn and soybeans, the rape was the lowest; (3)from the analytic results of EMD, the main factor of changes in virtual water content in Shangluo was short-term fluctuation; (4) based on the satisfaction of local grain demandfor human development, the total virtual water would account for 18.92% of the total local water resources in 2030. Total amount of virtual water based on grain supply would account for 10.87% of the total water resources in 2030, which would need to be transferred to the total virtual water by 8.05% of the total local water resources; (5) the water resources wereabundant in Shangluo City, but the grain self-sufficiency rate wasn’t high. There was a large number of crops with plentyvirtual water need to be transferred from other regions to meet the requirement of development. From the perspective ofvirtual water, the adjustment of crop planting structure of Shangluo City to reduce the amount of transferred virtual water is feasible.