Spatiotemporal changes of informal settlements: Ger districts in Ulaanbaatar, Mongolia

Ulaanbaatar, the capital of Mongolia, has experienced unprecedented urbanization following the collapse of the Soviet Union. Lack in housing supply has led to an expansion of informal settlements, mostly in the form of Gers — portable tents used by nomads in Mongolian Plateau. These settlements now host approximately 45% of Ulaanbaatar’s total population, resulting in some serious urban challenges (i.e., limited public services, waterborne diseases, and air pollution). However, there is a limited understanding on how these informal settlements have evolved because they have been constantly growing and changing over the past few decades. We conducted semi-structured interviews and applied remote sensing imagery to generate a comprehensive picture of informal settlements in Ulaanbaatar over the past three decades. Throughout the semi-structured interviews, we identified informal settlements as evolving objects with infancy, consolidation, and maturity stages. Through QuickBird and Landsat satellite imagery, we developed spatial distributions of informal settlements from 1990 to 2013 and found the total area of informal settlements increased from 32.15 km2 to 221.15 km2. We identified distinct spatial patterns of informal settlements (i.e., spillover, linear aggregation, leap-frogging, and infill development). Particularly, we verified that the emergence of informal settlements in the infancy stage occurred in the periphery of the city and along major roads, with informal settlements rapidly evolving over time (i.e., about 40% of infancy-stage in 1990 had segued into the consolidation and maturity stages in 2013). These results are credited to the accessibility of economic opportunities and public services, as well as the availability of vacant land and associated unique Mongolian land tenure law.