Tracking urban expansion in hazard-prone areas

The platform enables users to explore, analyse and download the dataset, while providing a range of tools to investigate how settlements have grown and changed, all at 10 m resolution and with updates every six months.

A key innovation of the WSF Tracker is its ability to monitor urban expansion with greater spatial accuracy, higher frequency and shorter lead time between satellite observation and publication of the dataset. This makes it possible to move beyond static snapshots of urban growth and towards a more continuous understanding of how cities and settlements evolve.

WSF Tracker offers a number of new analytical capabilities and insights, including:

• monitoring settlement growth continuously from 2016 to 2026, rather than comparing only a few static reference years;
• quantifying the timing and pace of urban expansion at global, regional, national and city scales; 
• identifying hotspots of rapid urban growth and emerging settlement patterns; 
• supporting more timely analysis of urban dynamics through six-monthly updates and reduced latency between observation and data availability; and 
• assessing settlement exposure to natural hazards by combining settlement dynamics with flood, subsidence, seismic, extreme heat and cyclone hazard layers.

But the WSF Tracker is more than a new dataset and platform, according to Fabio Cian, ESA representative to the World Bank. “It demonstrates how ESA, industry and development partners can work together to co-design solutions that respond to operational needs, create public goods, and support long-term institutional capacity,” he said. “The combination of high spatial resolution, frequent updates and reduced lead time between observation and data availability makes the platform particularly relevant for operational and analytical applications. The fact that the platform is already informing World Bank activities highlights the importance of building solutions with a clear pathway to adoption, scaling and sustainability from the outset.”

The WSF Tracker builds upon the World Settlement Footprint (WSF) initiative led by the German Aerospace Center (DLR) to map and monitor human settlements and related characteristics of the built environment worldwide. Developed jointly by DLR and MindEarth, and co-designed with ESA and the World Bank, it extends the WSF framework with a new capability to monitor settlement dynamics over time.

Why does urban expansion matter?

Cities or urban environments (excluding roads) cover 0.6% of Earth’s land surface as of January 2026, according to data from WSF Tracker. And yet these urban areas are home to more than 57% of the human population – a figure that is projected to grow to 68% by 2050 according to UN data.

As built-up areas continue to expand, understanding where and how urban growth is taking place is becoming increasingly important. In many regions, new development is occurring in areas exposed to flooding, extreme heat, seismic hazards, land subsidence and cyclones. This means that buildings, infrastructure and economic activity may be increasingly concentrated in locations where climate and natural hazard risks are also evolving.

The WSF Tracker helps address this challenge by providing a more frequent and detailed view of settlement growth. When integrated with global hazard datasets, the platform enables users to analyse how exposure to multiple hazards is evolving alongside urban expansion. This provides a new evidence base for urban planning, disaster risk management, infrastructure investment and development operations.

Flood risk for new-build areas

The example above shows the Vietnamese capital, Hanoi, with significant expansion over the past 10 years in suburban areas. The city itself lies in the Red River delta and parts of the suburbs are exposed to one-in-a-hundred-years flood risk as shown in the animation. The areas of new development are often in the more flood-prone areas of the city suburbs, where flooding is more likely to be deeper.

In Xi’an, in Shaanxi Province, central China, recent urban expansion is overlaid with the projected risk of subsidence by 2040 – shown in the animation above. The map indicates a spatial overlap between areas developed in the past decade and zones projected to face elevated subsidence risk. This pattern suggests that continued urban growth may be increasing the exposure of people, buildings, and infrastructure to future ground-deformation hazards.

Other examples from WSF Tracker show cities such as New Cairo, east of Egypt’s capital (animation above), and Pucallpa in Peru (right), both of which have undergone rapid urban expansion in the past decade. The shape of the new settlements on the outskirts of Cairo are particularly striking and have been referred to as Egypt’s new city in the desert. 

European cities such as Warsaw, in Poland, and Cologne (left), in Germany, show development around their suburbs, with much less development in the city centres. Asian cities such as Bangkok and Chengdu also experienced urban expansion, with Chengdu in China growing on the outskirts, while Bangkok, capital of Thailand, is shown on a local scale with rapid development.

Fabio added, “The platform is intended to help users better understand urban dynamics at the global scale, and we believe it could be of interest beyond the technical community. The availability of a fundamentally new dataset enables users to monitor where and when built-up areas have emerged, expanded, densified, or declined over nearly a decade.”