Monitoring slums and informal settlements in Europe: Opportunities for geospatial and earth observation techniques

The extent of slums and informal settlements in Europe and their population numbers are smaller than in Africa, Asia, or Latin America. However, such areas exist in different forms across Europe. This report reviews common forms, summarized as a European typology of slums and informal settlements. Furthermore, the report provides an overview of Earth Observation (EO) techniques for the development of monitoring systems to track the progress of the ?Leave No One Behind? principle. Understanding common forms of slums and informal settlements is essential for developing national and local SDG 11 monitoring systems, because techniques need to respond to the specific morphologies of settlement types. A systematic literature review concluded that there are six common forms of slums and informal settlements in Europe: 1) Refugee camps, 2) Roma camps and other traveller settlements, 3) Non (permanent) residential buildings, 4) Substandard housing, 5) Low-density informal sprawl, and 6) High-density informal settlements. Overall, EO data (e.g., satellite images) allow for almost real-time updated spatial information with high spatial resolution. Combining EO data and municipal databases permits mapping the locations, dynamics, and characteristics of slums and informal settlements. However, developing spatial information systems need to be part of an engagement process to protect vulnerable groups and co-develop strategies for improving living conditions.