A country scale assessment of the heat hazard-risk in the urban areas of Romania

Heat-related hazards pose major risks to our cities and the projected climate changes indicate substantial increases in impacts, and a better understanding of the interactions between environmental changes and human health are particularly critical for improving the living quality in urban areas in the climate change context. The considerable progress of monitoring, modelling, and analysing methods has addressed the increasing demand for enhanced accuracy, finer resolution, and better accessibility of climate products and services, including the specific needs of the built-up areas.

This study informs the present Heat Hazard-Risk (HHR) over the 262 cities of Romania using a risk matrix approach that aggregates the hazard triggered by high temperatures (i.e. Land Surface Temperature), and elements of vulnerability associated with the structure (i.e. Local Climate Zones - LCZ), and population density (i.e. number of inhabitants per 100 m² in each urban area).

The MODIS LST_cci products used in this study are customised TERRA_MODIS_L3C and AQUA_MODIS_L3C daily day/night 0.01° resolution data on an equal angle latitude/longitude data over Romania produced within the project LST_cci+ (CCI Land Surface Temperature, 2020), and covering the period 2000-2018. The LCZ values were extracted from a European database characterizing the urbanised landscapes derived within the World Urban Database and Access Portal Tools (WUDAPT) project. The population density was retrieved from the Joint Research Centre (JRC) database.

Generally, the HHR is higher in the central parts of the cities, but industrial and residential areas contribute to high-risk values towards the marginal perimeters too. The size and the industrial profile of a city impact the extent of the heat risk. For example, the biggest cities in the southern areas hold the most extended areas at risk at the country level. The land cover is a significant factor that controls the thermal hazard risk in the urban areas of Romania: the highest HHR values correspond to the discontinuous urban fabric, industrial and commercial units, and construction sites, while the lowest values stand for the urban forest, and water bodies.

This study has received funding from the European Space Agency (ESA) within the framework of the Land Surface Temperature project under the Climate Change Initiative (LST_cci), contract number 4000123553/18/I-NB.