京津冀城市群虚拟水流动格局变化对区域水资源压力的影响

Study on the influence of changing virtual water flow patterns in the Beijing-Tianjin-Hebei urban agglomeration on regional water pressure

【目的】合理的虚拟水调动是缓解水压力的重要途径,尤其在人口聚集的城市群地区,用水需求激增导致区域缺水问题严重。城市群内部不同地区间的紧密关联有助于促进虚拟水贸易,对优化城市群水资源配置、缓解水资源压力具有重要意义。【方法】采用多区域投入产出法,解析极端缺水的京津冀城市群内外间及其内部的虚拟水流动格局与变化,并揭示其对缓解区域水压力的作用。【结果】结果表明:(1)2012—2017年京津冀城市群与外部地区的虚拟水贸易量先增加后减少,而城市群内部虚拟水自给量却先减少后增加,2015年后京津冀内部虚拟水贸易增强;(2)京津冀城市群内部虚拟水流动格局呈现明显的时空异质性,虚拟水主要由经济相对欠发达的周边城市流入经济相对发达的中心城市(北京市、天津市、石家庄市和廊坊市),且随时间的推移,流动强度和向中心城市的集中程度均不断加强;(3)虚拟水流动明显缓解了京津冀中心城市的水资源压力,其实际水压力指数比虚拟水流动后的假定水压力指数年均下降12.12%,且下降程度逐年增加,但却加重了周边城市的水资源压力。【结论】京津冀城市群虚拟水流动有效缓解了中心城市的缺水压力,但不同城市的产业结构调整、虚拟水流动格局优化仍有很大提升空间。

[Objective]The strategic mobilization of virtual water can significantly mitigate water stress,especially in densely populated urban agglomerations.Rapidly growing urban populations have driven up water demand,resultsing in severe regional water shortages.However,the inter-connectivity between regions within an urban agglomeration is conducive to promote virtual water trade,which will be significant for optimizing water resources allocation and alleviating the pressure on water resources in urban agglomerations.[Methods]Based on the multi-regional input-output approach,this study analyzed the patterns and changes of virtual water flows between and within the Beijing-Tianjin-Hebei urban agglomeration with extremely water shortage,and revealed its role in alleviating regional water stress.[Results]The results showed that from 2012 to 2017,the trend for virtual water self-sufficiency within the Beijing-Tianjin-Hebei urban agglomeration decreased first and then increased,while virtual water trade with external regions followed an opposite trend.The virtual water trade between cities within the urban agglomeration had been strengthened after 2015.The virtual water flow pattern within the Beijing-Tianjin-Hebei region presented obvious spatial and temporal heterogeneity,primarily flowing from less developed peripheral cities to economically advanced central cities(Beijing,Tianjin,Shijiazhuang and Langfang).In addition,the intensity of flow and the degree of concentration to the central cities were increasing with time.Furthermore,the virtual water flow in urban agglomerations significantly alleviated the water stress in the central city,where the actual water stress index decreased by an average of 12.12%compared with the hypothetical water stress index after virtual water flows,with an annual increase in the degree of reduction.However,the water stress in surrounding cities increased.[Conclusion]The virtual water trade within the urban agglomeration effectively alleviates the water stress in central cities.However,the adjustment of industrial structure and the optimization of virtual water flow pattern still need to be continuously improved in different city.