Measurement of urban-rural integration level and its spatial differentiation in China in the new century

Urban-rural integration (URI), as a tendency of urban-rural development worldwide, is an inevitable way to create a coordinated and sustainable human society. China has been haunted by a variety of issues related to uncoordinated urban-rural interaction in recent decades and is in the midst of a critical stage faced with great challenges and opportunities as well in realizing urban-rural integration. Therefore, only by fully understanding the URI characteristics in different regions over vast China can we better formulate and implement targeted strategies and regionally adapted policies to boost URIs in the new era. This paper develops a conceptual framework based on the basis, driver and goal (i.e., BDG framework) of the URI system, which could potentially reflect the interaction mechanism between urban and rural areas. Then, the URI index (URII) was constructed based on 39 indices to measure the regional differentiation and explore the spatiotemporal evolution of the URI level from 2000 to 2018. The results showed that: (1) during the study period, the overall URI in China remained at a low level, and the evolution of the URII demonstrated a U-shaped curve, with 2006 as the inflection point, after which the URI level continuously increased. (2) The URII was characterized by significant spatial agglomeration as "high in the east and low in the western and central regions". Hot spots of the URI level included Beijing, Tianjin, Shanghai, Zhejiang and Fujian in China's eastern part, while the cold spots were concentrated in the transition zones between the eastern and western parts of China, mainly composed of Sichuan, Hubei, Shaanxi and Gansu. (3) Three types of URIs were identified using the latent profile analysis (LPA) method, corresponding to the early, middle and later stages of URI development in China, and their spatial distribution presented a gradient descending pattern from the southeast coast to the northwest. In the future, it will be necessary to focus on the characteristics of the basis-driver-goal indices and the nine related second-level indices of each URI type to strengthen the strengths and compensate for the weaknesses to further realize national URI development. This study will provide a scientific reference for the effective implementation of rural revitalization and regional coordinated development strategies.