| Urban is not only the center of human and economic activities but also a hotspot for building resource consumption and waste discharge.China is currently undergoing rapid and large-scale urbanization,leading to the exploitation of construction resources and waste generation.The limitation of resources and the emission of greenhouse gases have gradually become the constraints of urban sustainable development.Therefore,it is of great importance to study the spatio-temporal evolution of building material stock(MS)as well as its environmental impact to effectively manage building resources and realize sustainable development.This study focused on three representative urban agglomerations in China’s urbanization process: Yangtze River Delta urban agglomeration(YRD),Beijing-Tianjin-Hebei urban agglomeration(BTH),and the Guangdong-Hong Kong-Macao Greater Bay Area(GBA).Based on the nighttime light(NTL)data,this study proposed a MS accounting model at the urban micro-cell scale.The model was subsequently applied to long-term NTL data to reveal the spatial characteristics of MS in urban agglomerations and assess the environmental impact of building material stocks.In the last,the sustainable management of MS in urban agglomerations under the integrated development pattern was proposed.The main conclusions are as follows:(1)The MS in the YRD,GBA and BTH in 2020 were 34.87 billion tons,12.99 billion tons and 16.54 billion tons,respectively;Among all building materials,sand,gravel and brick made up the largest proportion of the total MS.The distribution of MS in the YRD was relatively balanced,mainly distributed in the axis of Shanghai,Hangzhou and Nanjing.The MS of the BTH was mainly concentrated in two core cities: Beijing and Tianjin.The regional gap of MS within BTH was obvious.In contrast,the MS in GBA was mainly concentrated in a few core cities in the central part of the urban agglomeration,and the core cities were closely connected with each other,forming an obvious contiguous-area of MS.(2)The MS in all urban agglomerations grew at a fast speed,but presented different development trends and characteristics in space.According to the spatio-temporal evolution characteristics of MS,the development modes of the three urban agglomerations can be categorized into three types: The first was the overall integrated development in the YRD,an integrated development model in which core cities were leading,and multiple axes developing together;The second was the partial integration in the GBA,in which core cities were highly concentrated and closely connected.However,radiative driving ability was limited to core cities,and the driving ability to develop edge cities was poor;The third development mode was primary integration in the BTH,here,the quantity of MS cores in urban agglomerations was small,although the magnitude was considerable.The cities were not tightly linked,and the driving role of core cities remained in its infancy.(3)In terms of the environmental impact of MS,during 2000-2020,the construction solid waste of the three major urban agglomerations increased from 106 million tons to 837 million tons,making construction waste disposal an arduous task.Construction solid waste and embodied carbon emissions were mainly generated in core cities.The newly generated buildings in the three major urban agglomerations in 2020 are expected to produce 907 million tons of carbon emissions,and show a trend of accelerating growth.(4)Improving the recycling rate of construction solid waste and extending the service life of buildings can significantly reduce the negative impact on the environment during the whole life cycle of buildings.For the expected newly generate MS in the YRD in 2030,if the steel recycling rate is increased to 80%,the embodied carbon emissions can be reduced by 55.7million tons.If the service life of buildings is increased to 70 years,it would reduce an average of 41.8 million tons of solid construction waste and 11.5 million tons of embodied carbon emission per year. |
PDF Full Text Request