三江平原粮食作物生产水足迹时空特征及影响因素

Spatio-temporal patterns and influencing factors of the water footprint of grain crop production in the Sanjiang Plain

水足迹是评价人类活动对水资源开采和水环境污染程度的重要方法,对农作物生长过程的绿水足迹、蓝水足迹和灰水足迹进行量化和分析,可以为农业用水综合评价和用水管理提供指导。以三江平原为研究区域量化粮食作物生产水足迹的时空特征,揭示粮食生产对区域水资源的占用情况,并分析水足迹的影响因素。结果表明:(1)三江平原粮食生产水足迹总量在2005—2018年间呈显著增加趋势,其中绿水足迹、蓝水足迹和灰水足迹在水足迹总量中的占比历年平均为28%、8%和64%;(2)粮食生产水足迹空间差异明显,在地市尺度,佳木斯市水足迹最高,占三江平原总量的47%,在县区尺度,富锦市、依兰县和桦南县是水足迹热点地区;(3)只考虑蓝水足迹,粮食生产给三江平原水资源造成轻度压力,而同时考虑蓝水和灰水足迹,粮食生产给三江平原水资源造成重度压力;各地市间水资源压力有较大差异,其中佳木斯市负担了该区域将近一半的粮食产量,水资源压力最高,鹤岗市则水资源压力最低;(4)降雨量、灌溉水利用效率、化肥施用量、粮食种植结构和作物单产水平等都会影响粮食作物生产水足迹,其中蓝水足迹响应种植结构的变化最敏感,灰水足迹响应化肥施用量的变化最敏感,而水足迹总量响应作物单产水平的变化最敏感。因此,建议减少化肥施用量、提高作物单产水平和优化作物种植结构纳入区域水资源可持续管理之中。

Water footprint is an important method to evaluate the degree of water exploitation and water pollution caused by human activities.The water footprint of production can be categorized into green water footprint,blue water footprint,and grey water footprint according to water resources.Green water footprint and blue water footprint evaluate water use and consumption,and grey water footprint assesses water pollution.The comprehensive analysis of green,blue,and grey water footprint of crop production guides water use management in agriculture.In this paper,we assessed the spatio-temporal patterns and influencing factors of the water footprint of main grain crops production in the Sanjiang Plain in China,and identified the pressure on regional water resources generated by grain crops production.The results showed that:(1)total water footprint of grain crops production in the Sanjiang Plain increased significantly from 2005 to 2018.The average proportions of green water footprint,blue water footprint,and grey water footprint in total water footprint were 28%,8%,and 64%,respectively.(2)The water footprint of grain crops production was significantly different among cities or counties.At the city level,the water footprint of grain crops production in Jiamusi was the highest,accounting for 47%of the total amount of the Sanjiang Plain.At the county/district level,Fujin,Ilan,and Huanan were hotspot areas,together accounting for 32%of the total amount of the Sanjiang Plain.(3)Only considering blue water exploitation,grain crops production caused mild water stress on water resources in the Sanjiang Plain,while considering both blue and grey water footprint,grain crops production caused severe stress on regional water resources.Moreover,water stress levels varied among cities,in which Jiamusi producing nearly half of the grain yield in this region suffered the highest water stress while Hegang suffered the lightest water stress.(4)Rainfall,irrigation water use efficiency,fertilizer usage,cropping structure,and crop productivity affected the water footprint of crop production.Blue water footprint was the most sensitive to cropping structural changes,grey water footprint was the most sensitive to fertilizer usage changes,while total water footprint was the most sensitive to the change of crop productivity.If the following measures are adopted:the productivity of the crops increased by 10%,the chemical fertilizer use decreased by 10%,10%of paddy fields turned to dryland crops,and the irrigation water use efficiency increased by 10%,the total water footprint can be reduced by 9.1%,6.7%,2.5%,and 0.1%,respectively.Considering both mitigation potential and feasibility,we suggest that reducing the amount of chemical fertilizer use,improving crop productivity,and optimizing the cropping structure should be considered for the sustainable management of regional water resources.