Urban Geo-Wiki

Crowdsourcing is one mechanism for undertaking e-participation. This chapter considers the broader issues of crowdsourcing in the context of citizen participation and governance, illustrated with a case study in which citizens are used to validate global maps of urban extent. Urban extent is an important source of information for a range of applications related to urban planning and governance such as hazard management, food security, health and climate change. Although different products are available that map urban areas or human settlements at a global scale, they disagree in terms of both total urban extent and the spatial distribution of urban areas. Samples of the urban extent from three major cities (London, Beijing and São Paulo), in areas where three recent global land cover maps disagree, are validated using data from a crowdsourcing campaign undertaken with the Geo-Wiki crowdsourcing tool. The results show that crowdsourcing has the potential to contribute to the validation of existing products of urban extent and could help users of these products to determine which map to use in a given location. More accurate information on urban extent will lead to better urban models and improved decision making, which will ultimately affect the future of a growing urban population. However, issues of sustainability, crowd retention and data quality remain challenging areas that require further research in the field of crowdsourcing.