The Colombian Atlas of Urban Expansion: Remote sensing to promote evidenced based planning

The Colombian Atlas of Urban Expansion is a tool recently created in partnership between The Marron Institute of Urban Management at New York University and The National Planning Department of the National Colombian Government. This work aims to promote evidence based planning by giving municipal officials and policy makers accurate information to inform and improve the decisions related to laws governing land and housing. The Atlas, analyzed the quality and quantity of growth of the urban extent of 118 municipalities and agglomerations of Colombian, a representative sample of the total universe of 1102 municipalities, allowing for the creation of statistical projections of the entirety of Colombia’s urban areas. The study used a very cost effective methodology based on remote sensing analyzing medium and high resolution satellite imagery that allowed to identify the changes over time during the last 3 decades on how much the urban areas of Colombia have grown and the changes on the quality of urban layouts. This produced metrics related to the area of the cities, such as: area of urban extent and metrics for density, saturation, compactness and cohesion. It also produced metrics related to share of land in roads, percentage of area within walking distance to arterial roads, share of land in the urban extent built and unbuilt and a general classification of land uses. It was found that Colombian cities are an outlier in terms of the growth of urban extents and the variation of densities in recent years. Whereas, in the world’s cities and in both more and less developed countries the urban extent grew at a faster rate than the population, in Colombia this was not the case, and densities did not decline with statistical significance. It was also found that Colombian cities became more saturated over time; in other words, there is less public space. Also, the average block size got larger, making cities less walkable. These two findings are similar to the conclusions of the global study conducted by New York University, UN-Habitat and the Lincoln Institute. This event will present key findings of the Colombian Atlas and will cover additional uses of this information, from urban planning to public health to monitoring the Urban SDG's.