Assessment of Gradient Effect and Driving Force of Megacity Expansion:A Case Study of Nanjing and Hangzhou
Impervious surface is an important index to measure the urbanization level and an important basis to explore the pattern of urban expansion.Taking the megacities Nanjing and Hangzhou as the research objects,the spatial and temporal expansion distribution characteristics and evolution trend of impervious surface in megacities from 1990 to 2020 were analyzed by means of urban expansion index method and gradient effect analysis.From the perspective of expansion area,the urbanization process has accelerated significantly since the 21st century,and the impervious surface of the megacities of Nanjing and Hangzhou has expanded significantly.From the perspective of dynamic changes,the urban expansion of Nanjing and Hangzhou was obviously different in time and space.From the perspective of gradient effect,the urban area radiated to the surrounding cities,and the gradient effect was obvious in distance,elevation,slope and other dimensions.From the perspective of driving force,urban expansion and development was the joint result of internal and external forces.Among economic factors,the output value of the primary industry,the secondary industry and the tertiary industry have the most significant impact.
万方数据
