Urban material flow in earthquake and post-disaster reconstruction

Earthquake and post-disaster reconstruction can be regarded as rapid urbanization．The systematic study of urban material metabolism could evaluate the state of urban construction and development．Bottom-up material flow analysis was used here to calculate stocks and flows of steel and cement in Guangyuan City from 2005-015 in five subsystems (buildings, infrastructure, transportation, durable goods and machinery)．The driving factors were then analyzed by LMDI method．Due to earthquake, stocks of steel and cement were found to have decreased significantly in 2008, but increased rapidly in post-disaster reconstruction from 2008-2011．In 2015, per capita stocks of steel and cement reached 3.2 x 10³ and 7.8 x 10³ kg respectively．However, the efficiency of material stocks gradually decreased after 2008, down to 50% of the national average．LMDI analysis found economic growth to be the main driving factor behind increases in steel and cement stocks, whilst improved efficiency in material-use was inhibitory to the increase．Therefore, in earthquake and post-disaster reconstruction, cities should establish a comprehensive waste-material recycling system, to complete industrial reconstruction and upgrading, and to strive to improve material-use efficiency and to achieve efficient urbanization development．