Qualitative Analysis of the Cooling Potential of the Streetside Vegetation of Kharagpur, West Bengal, India

Abstract

The urban heat island (UHI) effect is a major challenge in contemporary urban planning. The large number of paved surfaces, anthropogenic activities and combustion of fossil fuels are the major contributors of this phenomenon. Urban green spaces are known to mitigate the UHI. Since streets constitute a major portion of the urban areas, greening the streets can help reduce heat stress significantly. To study the impact of orientation and density of the street side vegetation on their cooling potential in Kharagpur, West Bengal, India. A suitable site, meeting the orientation and the density of vegetation criteria, was chosen for collecting the primary data through an instrument survey. Ambient temperature, surface temperature and solar radiation data was collected from the thirteen cross-sections marked across the site. As part of the preliminary data processing, relative variations of ambient temperature, surface temperature and the solar radiation attenuation was calculated. The values pertaining to these three secondary parameters were used to form matrices corresponding to each of the trees of each of the cross-sections. These matrices were then compared with their corresponding matrices to estimate which side exhibited a higher cooling potential. Besides, a colour-coded matrix was also generated from the calculated shade index to evaluate the amount of incident solar radiation blocked by each of these trees. This study corroborates the previous findings that the shade providing trees can alter the microclimate of the area. Besides, it was also observed that the Northern pavements of the east-west oriented streets are cooler than the Southern pavement. Furthermore, it was also noticed that if the crown of the tree is present at a greater height from the ground, then lower solar angle results in less blockage of the incident solar radiation. Also, it was evident that a higher density of tall, shade providing trees, maximally block incident solar radiation on a street. This study can help in understanding the pattern of cooling potential of the street side vegetation in a warm and humid climatic zone like Kharagpur so that the plantation can be planned judiciously.