Characterization of Urban Greening in a District of Lecce (Southern Italy) for the Analysis of CO2 Storage and Air Pollutant Dispersion

Abstract

This paper is devoted to the assessment of urban greening effects on two important ecosystem services, i.e., air quality and CO2 storage, including the corresponding economic impacts in a real urban area, i.e., a district located in the Mediterranean city of Lecce (southern Italy). Two tools were employed, i-Tree Canopy and the computational fluid dynamics (CFD) microclimate model ENVI-met. i-Tree Canopy allowed fully determining the land-cover percentage on the basis of different ground cover classes and obtaining an estimate of annual values of CO2 storage, air pollutant removal, and economic benefits in the presence of urban greening. The estimate in i-Tree Canopy considered only the amount of greening; therefore, air pollutant removal estimates were only potential. As the vegetation was located in street canyons, its interaction with local meteorology and urban geometry strictly affected the dispersion of nitrogen oxides (NOx) (taken here as an example) as obtained from ENVI-met simulations. In ENVI-met, both deposition/absorption and aerodynamic effects were considered, and local increases in concentration were found in the district. The analysis of results obtained from different tools (one complex (CFD model) and the other simple (i-Tree model)) showed the error associated with the simple model in the computation of impacts if the interaction among the vegetation characteristics, the meteorological conditions, and the urban geometry was neglected; however, it also uncovers a novel approach for comprehensively characterizing a given area in terms of its vegetation cover, CO2 storage, and economic benefits, as well as local effects on air quality. This study is set in a broader context aimed at assessing the air quality in urban canopies of Mediterranean areas characterized by the presence of narrow street canyons where pollutants can accumulate due to ineffective air exchange with the above atmosphere.

Combinative Study of Urban Heat Island in Ascoli Piceno City with Remote Sensing and CFD Simulation—Climate Change and Urban Health Resilience—CCUHRE Project

“…These evolutionary scenarios will measure thermo-regulatory actions related to energy efficiency or greening strategies (e.g., desealing, micro-forestation, rain gardens, green roofs, cool and high albedo/reflectance materials, etc.) as tested on various scales in several GIScience or ENVI−met studies [5,[44][45][46][47]. On the other hand, they will be completed with aestheticperceptive and socio-recreational analyses through an integrated, technological-traditional approach as developed in CCUHRE project.…”

Analysis of Urban Greening Scenarios for Improving Outdoor Thermal Comfort in Neighbourhoods of Lecce (Southern Italy)

“…Results showed that, on a typical summer day, the greening has a positive effect on thermal comfort by decreasing PMV of 2 points and MRT by 7 • C and that these variations are also related to urban morphology and greening type. Buccolieri et al [21] investigated the effect of greening in the "Santa Rosa" neighbourhood (also studied here) on the dispersion of nitrogen oxides (NOx) and on CO 2 storage. A further neighbourhood, "167", is under investigation and will be the subject of a future publication.…”

“…Regarding the Santa Rosa neighbourhood, Buccolieri et al [21] reported part of the experimental campaign, which is summarised here and compared with the Libertini one.…”

“…The simulation set-up, summarised in Table 1, is the same as adopted and validated in Gatto et al [1] and Buccolieri et al [21]. This choice is aimed at making the studies comparable and to further contribute to in-depth guidelines for policy makers.…”

Air Quality and Sustainable Development of Urban Agglomerations in the Mediterranean Area: Science, Technology and Policies

“…However, the assessment of greening effects in urban areas is a complex task [6], as detailed in the study of the Santa Rosa district in the Mediterranean city of Lecce, located in Southern Italy. Lecce is a medium-sized city of 96,534 inhabitants, representative of Mediterranean cities in terms of architectural design and climate.…”