Socio-spatial segregation of household registration based on a spatiotemporal index at the individual level: A case study of 10 towns in Shanghai suburbs

Socio-spatial segregation is a critical issue of urban studies. With the increase of human mobility, the traditional measurements of residential segregation based on aggregated data show limitations. Few studies have explored the segregation in residents' daily activity space outside their living spaces, or the spatiotemporal patterns of segregation level in different periods of a day. Thus, it is necessary to study the individual-based socio-spatial segregation in various geographic and temporal contexts. Using data from a household travel survey in 10 typical towns of the suburbs of Shanghai in 2017, this study researched the spatiotemporal characteristics of household registration segregation in people's daily life based on a creative individual-based proximity index, which measures the proximity of various groups in different geographic contexts with various activity types and time periods. We divided a day into eight periods and used the i-STP index to measure the spatiotemporal pattern of segregation of four kinds of household registered residents. By dividing Shanghai into hexagonal grids with an actual area of 5 km², the average value of i-STP within each grid was calculated. Then Arcscene 10.2 was used to visualize the results. Results show that the average i-STP is higher in work activities during weekdays and is lower in recreation activities on weekends, indicating the distinctions of segregation levels in different activity contexts. Results also show that lower i-STP is detected during commuting time (6:00-9:00) and leisure time at night (18:00-21:00) on weekdays and the average i-STP reaches the minimum in the afternoon (15:00-18:00) on weekends. We also found that residents with different household registration types have different spatiotemporal segregation patterns and that the working place and activity place of residents in day time shows higher segregation level than the living place at night. The study provides a new measure of segregation from an individual-based and dynamic perspective, which can fill the gap in the existing research on segregation based on activity space. The results of the study indicate that attention should be paid to the segregation of different types of registered population in work and leisure activities in large cities of China to enhance the interaction between different groups.