Prioritizing the areas for tree planting to help decrease the effect of extreme heat based on Heat Risk Index in the city of Brno
This analysis serves as an illustrative example showcasing the utility of the Heat Risk Index and highlights the huge capabilities of ArcGIS as a powerful software equipped with extensive datasets and numerous analytical tools. The flexibility of ArcGIS positions it as a valuable resource for cities engaged in adaptation planning, offering a comprehensive suite of features to address complex challenges related to climate resilience.
Human-induced climate change is particularly evident in urban areas. One of the most important and most extensively studied effects of climate change in urban areas is the increase of air temperature in the city in relation to surrounding areas. This phenomenon is called the urban heat island. Due to the highly transformed surface and the release of heat in municipal and industrial processes, meteorological conditions are subject to numerous modifications. The urban heat island occurs mainly at night, during windless and cloudless weather and it is then that the greatest differences in air temperature between the urban area and its surroundings should occur. Modifications in air and surface temperatures cause significant changes in the living standards of populations around the world. Urban areas are overheating, which is particularly noticeable in the summer. Moreover, this effect is becoming bigger with increasing urbanization.
In response to extreme heat events, cities can incorporate strategic and localized adaptation plans, such as the implementation of green or cool roofs, or increased vegetation and trees to help lower urban temperatures. Initiating this process involves establishing a Heat Risk Index (HRI), which serves as the foundation for a localized adaptation plan for extreme heat. By leveraging the HRI, cities can identify specific areas within the community that warrant prioritized attention in the adaptation plan, facilitating a targeted and effective approach to reducing the urban heat island effect. The choice of input variables will depend on the purpose of the spatial analysis.
The study area covers the city of Brno in the Czech Republic with a total area of 224.18 km2. The purpose of the analysis was to prioritize the areas for tree planting to help decrease the effect of extreme heat. In order to create a heat risk index for the given objective, three input variables were considered: land surface temperature, tree canopy coverage and population density. As the calculated input values used different units of measurement, the standardization was carried out. Subsequently, the standardized values were combined to obtain a Heat Risk Index. The results were presented on the map and analyzed.
All data used in this study were retrieved from ArcGIS Living Atlas provided by Esri, which holds a collection of ready-to-use global geographic content, such as imagery, basemaps, boundaries, demographics, earth observations, urban systems and historical maps. Boundaries of the city with a total population count were extracted from ‘’Czech Republic Postcodes5 Boundaries’’ layer. Land surface temperature was derived from the ‘’Multispectral Landsat’’ imagery layer by extracting one of the two multispectral bands from Thermal Infrared Sensor (TIRS) held by Landsat 8 and Landsat 9 imagery. Tree canopy coverage was calculated using ‘’The European Space Agency WorldCover 2020 Land Cover’’ layer. This map contains 11 different land cover classes at 10 m resolution including ‘’Tree Cover’’ class, which contains any geographic area dominated by trees with a cover of 10% or more: areas planted with trees for afforestation purposed and plantations as well as tree covered areas seasonally or permanently flooded with fresh water except for mangrove.
Heat Risk Index (HRI) per each postcode area in the city of Brno