Regional environmental risk assessment and management guide for rapid urbanization process of a city cluster in China

In past decades, China has experienced rapid urbanization, which has brought about environmental changes. The assessment of regional environmental risk (RER) is a complex study for evaluating risk associated with risk sources, risk receptors, and risk retardation under uncertainty. This study aims to evaluate the RER through the holistic macro-assessment, and to ascertain management guide for rapid urbanization to diminish the RER. The results of our case study in the Su-Xi-Chang city cluster, which is a metropolitan area that largely contributed to the economic growth of Jiangsu Province, showed that the RER scores constantly increased from 0.506 to 0.817 during the period from 2001 to 2011. Coupled with the current tendency, in addition, scenario predictions revealed that rapid expansion of urban land would cause a multiple increase in RER. However, RER would begin to decline if the rate of urban population growth (UPG) stabilizes at 1.7%. Moreover, when the urban population ratio increases to 78% along the previous trend, a higher UPG corresponds to a lower declining rate of RER. Otherwise, a lower UPG corresponds to an earlier decline of RER. Finally, implementing city cluster plans was discussed to provide a scientific basis for guiding risk management and sustainable development of urbanization.