湖南省水稻水足迹计算及其变化特征分析

本文运用水足迹的理论和方法计算了湖南省水稻水足迹，并分析了其历史变化和构成特征，以期为水资源合理利用和农业结构调整提供依据和建议。结果表明：湖南省水稻水足迹由1960年的22×109 m3上升至2008年的34.4×109 m3，增加了12.4×109 m3；水足迹构成以绿水为主，但所占比例逐渐降低，灰水足迹由7%增加到24%，说明所需稀释水量逐渐加大；早、中、晚稻的水足迹以晚稻最大，占到总水足迹的38%~48%，其次是早稻，最少是中稻；早、中、晚稻的绿水占各自水足迹的比重依次降低，蓝水比重依次增加，灰水比重均在21%以上；从单位产量水足迹来看，双季稻平均比中稻少23.3 m3/吨。综合考虑水资源和产量因素，双季稻在有效利用水资源和保障粮食安全方面比单季稻更有优势，建议减少单季稻，增加双季稻种植面积。

The Water Footprint and Its Temporal Change Characteristics of Rice in Hunan

The water footprint of rice in Hunan Province was calculated,and the historical change and the composition characteristics wew analyzed,to provide a basis and advice for the rational use of water resources and adjustment of agricultural structure.The results showed that： the water footprint of rice in Hunan Province was from 22×10 9 m 3 in 1960 up to 34.4×10 9 m 3 in 2008,an increase of 12.4×10 9 m 3 ;green water footprint accounted for the main and declining,the proportion of gray water footprints was from 7% to 24%,indicated the gradual increase in the required amount of water dilution;the water footprint of late rice accounted for 38%-48% of total rice footprint and was the most portion,followed by early rice and mid-season rice;green water proportion of total water footprint of each early,middle and late rice was increased in turn and blue water was decreased in turn,gray water were more than 21%;the unit yield of water footprint of double cropping rice was less 23.3 m 3 /t than middle-season rice average.Comprehensive consideration of water resources and yield factors,double cropping rice were more advantages than single cropping rice in the effective use of water resources and food security.So,it is recommended and reduce single cropping rice and increase the double cropping rice cultivation.