Green infrastructure’s impact on thermal condition in arid & semi-arid cities: a systematic review

Aims: Research shows that the urban heat island (UHI) effect raises temperatures in cities, while green infrastructure helps mitigate heat, especially in arid and semi-arid regions. However, more targeted studies are needed on its cooling capacity in these climates. Methodology: In leading study, A systematic review was conducted to analyze research articles focused on arid and semi-arid cities. By detailed and targeted searches in valid databases based on keywords and then monitoring them, 31 selected articles were selected for final analysis. Research reviewed were divided into three categories based on the studied scale. Findings: The first category, studies that examined the cooling effect of green infrastructure in the whole city (41.94%), studies that examined the effect of green infrastructure on several parts of the city (35.48%), the effect of green infrastructure on one part hecked from the city (22.58%). Most of the research reviewed has investigated the generalities of green infrastructures such as vegetation or trees and lawns on a large scale and has less focused on the specific features and details of green infrastructures, as well as the combination of urban green infrastructures with different urban forms. Conclusion: Although large green infrastructures significantly improve the temperature conditions of cities, the contribution of small and medium infrastructures, such as urban parks in dry and semi-dry cities, should be addressed because the development of such spaces is often faced with less intervention and cost. By modifying plant cover types and structural characteristics of vegetation and tree canopies, the cooling capacity of existing green infrastructure can be enhanced in dry and semi-arid cities, a topic that has been less explored in reviewed studies. In addition to all these cases, the urban green infrastructure program, based on its cooling capability, should be considered part of urban land use planning in dry and semi-dry cities to achieve the most optimal result.