Improved exposure and risk assessment in the EU, by modelling population distribution in daily and seasonal cycles: the JRC’s ENACT project
By Sérgio Freire and Marcello Schiavina
A set of seamless nighttime and daytime population density grids for each month of the year, which take into account human activities and induced major daily and monthly variations, and covering all 28 EU Member States, has been produced as part of the JRC Exploratory Research Project ENACT (“Enhancing Activity and Population Mapping”). These new spatio-temporal grids have been created by mining and combining official statistical data at regional level with geo-spatial data from conventional and non-conventional data sources. These population data sets are validated and will be freely available to the public.
A core component of disaster risk is exposure. Without exposure there would be no impacts from hazards. Particularly for some types of natural hazards, risk can only be reduced by decreasing exposure and vulnerability, as the hazard component is quite inflexible. Earthquakes and volcanic eruptions, for example, are difficult to predict, and we cannot reduce the magnitude of such events. People are the most vital asset to be protected, and so adequate planning, mitigation, and reaction to disasters requires knowing the location of people and their characteristics. Geospatial data on population and human settlements are fundamental to know where and how we live. Disaster risk reduction requires informed decisions, yet there is much to be learned about the global distribution of population and settlements, and its past and future evolution.
Moreover, although hazard events are often unexpected, striking at any time, day or night, maps of human exposure usually provide a static and incomplete picture, typically representing one moment in time (e.g. resident population in a nighttime population distribution, if based on census data). In reality, human activities (work, study, leisure, etc.) result in large fluctuations in population distribution at a range of spatio-temporal scales. Such population dynamics greatly affect the patterns and assessment of population exposure, particularly for rapid onset hazard events like floods, earthquakes, and tsunamis. These implications are largely overlooked in risk analyses, or considered only for small areas and case studies, mainly due to a lack of data on population spatio-temporal dynamics.
The availability of data sets such as those developed in the ENACT project, opens the way for a consistent and detailed analysis of the daily and seasonal variations of population exposure and risk, across the 28 EU countries inhabited by more than 500 million people. By combining these population grids with the most recent hazard data on seismic and flood hazard, for example, we can map and quantify variations of population exposure, study their spatio-temporal patterns, and eventually identify potential daily and seasonal exposure hot spots. Although most useful for baseline risk assessment, such population grids can benefit all stages of the disaster management cycle and promise to contribute substantially to advancements in natural hazard risk assessment models.
ENACT was a two-year JRC Exploratory Research Project (2016-2017), involving various units at the JRC.