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How geospatial technology can help cities plan for a sustainable future

Xueman Wang's picture
In this video, representatives from the World Bank, GEF, and City of Johannesburg discuss the impact of geospatial tools on urban planning.

Many urban residents these days will find it hard to imagine a life without mobile apps that help us locate a restaurant, hail a cab, or find a subway station—usually in a matter of seconds. If geospatial technology and data already make our everyday lives this easier, imagine what they can do for our cities: for example, geospatial data on land-use change and built-up land expansion can provide for more responsive urban planning, while information on traffic conditions, road networks, and solid waste sites can help optimize management and enhance the quality of urban living.

The “urban geo-data gap”
 
However, information and data that provide the latest big picture on urban land and services often fail to keep up with rapid population growth and land expansion. This is especially the case for cities in developing countries—home to the fastest growing urban and vulnerable populations.

The Global Urban Footprint: A map of nearly every human settlement on Earth

Thomas Esch's picture


Urbanization is increasingly central to the global development process, but until recently, basic spatial information on the world’s urban areas has been unavailable, inconsistent, or unreliable. The lack of consistent data on the world’s cities makes it hard to understand the overall impact of urbanization. However, innovations in geospatial mapping are now helping to provide one major piece of the puzzle:maps of practically all built-up areas around the world are available thanks to new uses of satellite data.
 
Scientists at the German Aerospace Center (DLR) have succeeded in using a newly developed method to map the world’s built spaces at an unprecedented spatial resolution, resulting in the ‘Global Urban Footprint’ (GUF), a global map of human settlements at a spatial resolution of 12 meters per grid cell (aggregated to 75m for public use).
 
The German radar satellites TerraSAR X and TanDEM X acquired over 180,000 images between 2010 and 2013, which were processed, together with additional data such as digital terrain models, to produce the Global Urban Footprint. In total, the researchers processed over 20 million datasets with a combined volume of more than 320 terabytes.

What does “urban” mean?

Chandan Deuskar's picture
Follow the author on Twitter: @cd_planner
 

 
This aerial view of Hanoi, Vietnam, clearly shows areas of decreasing density between the city and the countryside, making it hard to define the limits of the "urban" area.
Anyone reading this blog is likely to have heard the statistic that ‘over half of the world’s population now lives in urban areas’. This has been the standard opening line of reports and presentations about urbanization since this milestone was supposedly reached in 2008. But what does it really mean?

In everyday usage, terms related to human settlements have vague, shifting meanings. What one person might describe as a small ‘city’ might be a ‘town’ or ‘village’ for someone else; one person’s ‘megacity’ might be a cluster of cities from a different perspective. Similarly, we can usually identify areas that are clearly within a city and others that are outside it, but there is usually a peri-urban area of intermediate density that usually lies between the two, making it hard to define a clear city limit. Formal administrative boundaries may have historic or political meaning, but are rarely aligned with the physical or economic extents of the urban area.

What exactly is a city? It depends who you ask

It turns out there is no standard international definition of an ‘urban’ area or ‘urban’ population. Each country has its own definition, and collects data accordingly. The statistic that 50% of the world’s population is urban is arrived at simply by adding up these incomparable, and sometimes conflicting, definitions.