中国灌区粮食生产水足迹及用水评价

以1998、2005 及2009 年459 个灌区资料为基础,从区域尺度计算粮食生产水足迹,建立粮食生产用水水平综合评价指标I对灌区粮食生产与水资源利用之间的关系进行评价。结果显示:粮食生产水足迹及其组成的区域间差异均较大,大值省区主要分布于东北、华南,小值省区以黄淮海平原为核心集中分布;全国粮食生产水足迹多年均值为1.336 m³/kg,蓝、绿水比例分别为63.7%和35.8%,有35.1%的水足迹损失于粮食生产过程。空间自相关分析表明,粮食生产用水水平综合评价指标I相似的省区在空间上显著地聚集,局部自相关属性为HH和LL的省区超过了20 个,不同年份总体和局部的空间分异特征随时间变化均不明显;省区间粮食生产综合用水水平差异大,I值介于0.079~0.889 之间,变异系数为0.59,黄河中下游省区用水水平较高而东北及西北大部分省区则相反。结合人均粮食占有量与I值在全国的地位,对各省区粮食生产与农业用水发展方向进行了讨论。

Agriculture Water Utilization Assessment Based on Water Footprint of Grain Production Evaluation in Irrigated Farmland of China

The purpose of this study is to assess the agricultural water utilization in irrigated farmland of China based on water footprint of grain production evaluation. Having collected the data of 459 irrigation districts in 1998, 2005 and 2010, this paper calculates the grain production water footprint (GPWF) in irrigated farmland of China from a regional scale, and it then analyzes the relationship between grain production and agricultural water use by establishing an integrated water-grain rationality assessing indicator (I). The analyzed result shows that GPWF in Northeast and South China is high, while the low values are located around Huang- Huai-Hai Plain. GPWF in the regions of Hainan, Jilin, Liaoning and Heilongjiang exceed 2.400 m³/kg, while no more than 1.000 m³/kg in other six provinces, including Beijing, Shandong, Henan, Shanxi, Shaanxi and Hebei. The national value of GPWF during the study period is 1.336 m³/kg and the shares of blue and green water footprint are 64.1% and 35.9% respectively, and about 35.1% of the water footprint is not used for the crop evapotranspiration (ET). Same with the GPWF, the spatial difference of blue and green water footprint composition is big. Proportion of green water in GPWF as a whole (R_G) in Hubei is 58.5%, ranking the highest of all the 31 provinces of China. The RG in Zhejiang, Shandong, Henan and Sichuan is also above 50.0%. R_G in other 13 provinces is below the national value and no more than 20.0% in Jilin, Ningxia and Xinjiang. Spatial autocorrelation analysis results show that provinces with resembling water productivity values demonstrate significant aggregation. Local autocorrelation analysis reveals that more than 20 provinces show high- high positive autocorrelation (HH) or low- low positive autocorrelation (LL). General and regional spatial differentiation characteristics among the selected years are insignificant. The value of I is significantly different among provinces, which fluctuates between 0.114 and 0.850 and the variation coefficient is 0.55. Water use in regions located in the middle and lower reaches of the Yellow River is rational while the situation is the opposite for most areas of Northeast and Northwest China. The index I could explain the differences of relationships between grain production and water use in different regions. The 31 provinces are divided into four categories according to the parameters of agriculture water utilization and grain production capability, and the policies in resources management and food security safeguarding of all categories are discussed in this paper. Water footprint and water utilization in some regions could be improved significantly, especially the provinces in Northeast and Northwest China.