Spatiotemporal Analysis of the Formation of Informal Settlements in a Metropolitan Fringe: Seoul (1950–2015)

In many metropolitan areas, the urban fringe is defined by highly sensitive habitats such as forests and wetlands. However, the explosive growth of urban areas has led to the formation of informal settlements in the urban fringe, subsequently threatening these sensitive habitats and exaggerating several social and environmental problems. We seek to improve the current understanding of informal settlements and their formation in the metropolitan fringe through a comprehensive spatiotemporal analysis of the Guryong Area (GA) in the Gangnam District, Seoul, South Korea. We measured the land-use and land-cover (LULC) changes in the entire GA from 1950 to 2015, and then analyzed the changes in one specific land-use type defined as “spontaneous settlements”. We then combined these changes with landform and slope data in 600-m-wide bands along the gradient of urbanization. The results showed spontaneous settlements distributed in small clusters in 1975, and the growth of this distribution into larger, more condensed clusters beginning in 1985. Between 1950 and 2015, the total area of spontaneous settlements decreased, while the settlement locations shifted from the urban core to the marginal area of the GA. Meanwhile, the locations selected for spontaneous settlements moved from plain areas with slopes of 2–7%, to more steeply sloped, remote areas such as the mountain foothills with slopes of 15–30%. These results suggest that the spatial characteristics of informal settlements are shown in the degree of aggregation and marginalized trend indicated from the analysis of spontaneous settlements. Finally, we hope the spatial analysis can be used as a basis and starting point for the evaluation process of informal settlement redevelopments in other areas of Seoul, as well as in other Asian cities.