[关键词]
[摘要]
为全面客观评价城市化进程中水资源利用状况,揭示水资源利用过程中的驱动因子,以北京市为例,基于水足迹理论与LMDI模型,分析计算2003—2018年水足迹变化以及经济、技术和人口对水足迹变化的驱动效应。结果显示:北京市总水足迹经历了2个阶段,第1阶段在2003—2011年为波动阶段,第2阶段在2012—2018年为下降阶段。水足迹变化总体呈良性发展,但输入依赖度均大于25%,需要进一步优化内部水资源利用效率和产业结构,保障水资源生态安全;水资源可利用增长指数持续增加,可持续性增强,生态安全有所改善,但仍处于严重超载状态;对北京市水资源利用量变化起决定性的驱动因素是技术效应,其次是经济效应,人口效应占比最小。城市发展过程中应注意经济发展和人口增加带来的用水量的增加,重视发展节水科技,转变水资源的开发利用方式,从而实现水资源可持续发展。
[Key word]
[Abstract]
In recent years,with the continuous acceleration of industrialization,rapid social and economic development and continuous population growth,water consumption in various industries is increasing,and the contradiction between supply and demand is aggravating.Water consumption includes not only physical water but also virtual water in products and services.The purpose of water footprint theory is to study invisible water in the public consumption and service process.Beijing is a typical water consumption city,but there is no research on water resources utilization from the perspective of water footprint theory.Therefore,based on water footprint theory,it is necessary to evaluate the utilization of water resources in urban physical water,virtual water,and trade. The internal water footprint and external water footprint are calculated based on water footprint theory,including agricultural virtual water consumption,industrial virtual water consumption,domestic water consumption,ecological environment water consumption,virtual water outlet,and external water footprint is virtual water inlet.At the same time,the LMDI model is applied to decompose different factors such as structure effect,technology effect,and population effect of water footprint change. The total water footprint of Beijing showed a fluctuating downward trend from 2003 to 2011 and from 2011 to 2018,respectively.Among them,agricultural and industrial water footprint has a downward trend year after year,living and ecological water footprint has an upward trend;virtual water quantity of import is greater than virtual water quantity of export.In terms of water footprint structure,the selfsufficiency rate of water resources is generally on the rise,exceeding 70% by 2015,and the dependence on water resources imports is on the decline side.In case of water footprint sustainability,the water footprint growth index is mostly negative and the available water resources growth index is positive.In terms of ecological safety of water resources,both the water shortage index and pressure index are greater than 1,and the water resource pressure index is on the decline as a whole.Likewise,in terms of water footprint benefits,the economic benefits of water footprint are on the rise,the water load index is on the rise,the net trade value of water footprint and the contribution rate of water resources are on the fluctuating stage from 2003 to 2011,and from 2011 to 2018.Among the drivers of water footprint,the proportion of population effect is less than 10%,the economic effect is less than 40%,and the technical effect is more than 50%,respectively. Water footprint accounts for about 70% in Beijing,mainly in agriculture.However,with the acceleration of urbanization,population growth, industrial structure changes,agricultural water footprint is getting lower and lower,and ecological water footprint and living water footprint are increasing.The total water footprint is on a downward trend and its dependence on imports is decreasing.Water resources are developing in Beijing,and the import dependence is high.From the perspective of the water footprint development trend,the overall development of Beijing is in two stages,fluctuating from 2003 to 2011 and declining from 2012 to 2018.Since 2012,the sustainable development of water resources in Beijing has been benign and in a sustainable state.Due to the shortage of local water resources in Beijing,both the water shortage index and pressure index are relatively high,and the ecological safety of water resources is in a serious overload situation.Although the internal economic benefit of water resources is increasing continuously,the external water diversion still needs to be increased due to heavy load. Based on the LMDI model analysis,it can be seen that the driving factors of water resources change in the process of urbanization are technology effect>economy effect>population effect.Only technical effect is driven in the opposite direction,while economic effect and population effect are both driven in the positive direction.It indicates that great attention should be paid to the increase of water consumption brought by economic development and population growth in the process of urbanization and that sustainable attention should be paid to the development of water-saving technology,the optimization and adjustment of industrial structure, and the improvement of water resource utilization efficiency to realize the sustainable development of water resources.
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