【摘要】 通过依据典型区县实际灌溉定额调查成果并用全国作物需水量等值线图进行修正,确定出北京市主要农作物的需水量,对北京农作物种植结构变化、农业用水及其GDP效益作了分析,进而对各类农作物历年的虚拟水含量及其结构变化进行了研究,最后基于投入产出方法对北京农业虚拟水贸易进行了计算分析.结果表明,①近年来,北京地区粮食作物虚拟水总量持续减少,由1990年的18.32×108m3减少到2004年的4.283×108m3,经济作物虚拟水总量却呈上升趋势,由1990年的9.06×108m3增加到2004年的14.92×108m3,但总体上农作物虚拟水总量仍呈现下降趋势;②北京是一个农产品虚拟水净输入的地区,年平均虚拟水净输入量约为2.37×108m3,这相当于北京市年产水资源总量的5.93%,间接地缓解了北京市水资源紧缺的局面.更多还原

【Abstract】 Based on the irrigation norm of typical district and county,and revised by the isoline map of Chinese crops water demand,the change of crops program was analyzed as well as the agricultural water use and its GDP benefits.Then the virtual water was calculated for years.At last,the input-output method was used to calculate the trade of virtual water in Beijing.As the results,the virtual water for cereal crops has been decreasing in Beijing,from 1.832×10~9 m~3 in 1990 to 4.283×10~8 m~3 in 2004.Otherwise the virtual water for technical crops has been increasing,which is from 9.06×10~8 m~3 in 1990 to 1.492×10~9 m~3 in 2004.On the whole,the virtual water for crops has been decreasing in Beijing.From the angle of primary products Beijing is a virtual water importing area.Virtual water importing of annual average is 2.37×10~8 m~3,which is about 5.93% of the total water of Beijing.Virtual water has been an important supplement of local real water of Beijing.更多还原