Impact of rapid urbanization on urban heat island effect in a typical valley-city

Global warming and rapid urbanization have great impacts on local temperature and urban heat island (UHI) effects. However, most of the previous research paid very little attention to the impact of natural terrain on UHI effects. This work reported the effects of complex terrain on UHI characteristics. As the second largest city in Northwest China, Lanzhou was selected as the research region since it is a typical valley city with rapid urbanization processes. We analyzed the variation characteristics of UHI effects at annual, seasonal and daily scales, in order to explore the differences and similarities of UHI effects between plain cities, coastal cities and valley cities. Then we evaluated the contribution of urbanization effect to urban surface temperature change. Finally, we examined the link between urbanization and UHI effects. The results of this study will be useful to urban planners and environmentalists in ecological environment construction, urban architectural design and urban planning.