Geospatial localization analysis of green infrastructure development assumptions in urbanized areas concerned by air quality: the case of Sofia Municipality, Bulgaria

Abstract

This study presents a methodological approach and the results of a geospatial localization analysis of selected residential areas of the Sofia Municipality, which are highly vulnerable in terms of ambient air quality (AQ). The objective is a scientifically sound selection of locations for the construction of additional green infrastructure (GI) elements. A targeted selection of 13 indicators was carried out on urban morphology, demography, geo-ecological conditions, and an annual average concentration of pollutants. The output data are organized in a spatial grid (250/250 m). A weighted overlay was performed to identify cells with a high need for the construction of GI as additional measures to regulate microclimatic conditions and the associated AQ. Additional prioritization has been carried out for units with largest number of schools, kindergartens, hospitals. They have been surveyed with unmanned aerial systems (E-BeeX SenseFly). A digital surface model in 3D point cloud and an orthophoto map were generated in Pix4D environment. As a result, 401 specific land properties have been identified for the construction of new GI or upgrading of existing GI elements to increase the potential for effective regulation of the urban microclimate and mitigation of the negative effects of air pollution. The study was conducted in 2022 by the National University Center for Geospatial Research and Technology on behalf of Sofia Municipality. The results will be used for the expansion of parks and gardens, the afforestation of inter-block spaces ("mud patches"), the greening of schoolyards and kindergartens, busy transport arteries, or other innovative green solutions.