城镇化是城镇和乡村人口变动共同作用的结果。假设某地区初始城镇常住人口为uo,乡村常住人口为ro,一段时期后,城镇和乡村常住人口增加分别为△u、△r。基于城乡人口的变动可将城镇化地域类型划分为“城乡扩张型”(Δu>0,Δr>0,Δu/u₀>Δr/r₀)、“城镇吸引型”
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%EF%BC%88%3C%2Fmo%3E%3Cmi+mathvariant%3D%22normal%22%3E%CE%94%3C%2Fmi%3E%3Cmi+mathvariant%3D%22normal%22%3Eu%3C%2Fmi%3E%3Cmo%3E%26gt%3B%3C%2Fmo%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmi%3E%CE%94%3C%2Fmi%3E%3Cmi%3E%E1%B5%A3%3C%2Fmi%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmn%3E0%3C%2Fmn%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3Cmi%3E%CE%94%3C%2Fmi%3E%3Cmi%3E%E1%B5%A4%3C%2Fmi%3E%3Cmo%3E%26gt%3B%3C%2Fmo%3E%3Cmo%3E-%3C%2Fmo%3E%3Cmi%3E%CE%94%3C%2Fmi%3E%3Cmi%3E%E1%B5%A3%3C%2Fmi%3E%3Cmo%3E%29%3C%2Fmo%3E%3Cmi%3E%E3%80%81%3C%2Fmi%3E%3C%2Fmath%3E)
“乡村流失型”(Δu>0,Δr<0,Δu<-Δr)、“城乡收缩型”(Δᵤ<0,Δr<0,Δu/u₀>Δr/r₀)和“逆城镇化”
![](https://math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmo%3E%28%3C%2Fmo%3E%3Cmi%3E%CE%94%3C%2Fmi%3E%3Cmi%3E%E1%B5%A4%3C%2Fmi%3E%3Cmo%3E%2F%3C%2Fmo%3E%3Cmsub%3E%3Cmi%3Eu%3C%2Fmi%3E%3Cmn%3E0%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmo%3E%26lt%3B%3C%2Fmo%3E%3Cmi%3E%CE%94%3C%2Fmi%3E%3Cmi%3E%E1%B5%A3%3C%2Fmi%3E%3Cmo%3E%2F%3C%2Fmo%3E%3Cmsub%3E%3Cmi%3Er%3C%2Fmi%3E%3Cmn%3E0%3C%2Fmn%3E%3C%2Fmsub%3E%3Cmo%3E%29%3C%2Fmo%3E%3Cmo%3E++%EF%BC%8C+%3C%2Fmo%3E%3C%2Fmath%3E)
“逆城镇化”地区在我国很少。下图为“2000~2020年我国城市群、中心城市规模与城乡人口变动图”。据此回答下面小题。
![](http://tikupic.21cnjy.com/2023/12/04/4f/e6/4fe65d7d9f755f7e20977d0bbb5cb5fc_602x220.png)