Surface Temperature Analysis of Community Garden Compared to
Census Block Groups in Philadelphia
Halina Takahashi
Villanova University
Introduction
Extreme urban heat presents negative impacts on the health of urban communities. There is a direct correlation between green features, heat index, and health impacts on children. Latinx children in particular are vulnerable to heat related illness and lack of physical activity due to the inequitable nature of urban communities (Lanza et al., 2021).
Urban gardens provide many benefits such as their ability to increase social capital, civic engagement, sustainability, and food security (Lindner, 2021). Gardens can also reduce urban heat islands and increase stormwater retention, along with many other ecosystem services (Clarke et al., 2018).
In addition to these economic and ecological benefits, community gardens also presents a cooling potential for communities (Lanza et al., 2021). This specific characteristic of urban gardens is has not been well studied.
In this study, I examine the surface temperatures of community gardens across Philadelphia and compare them to that of the census block groups in order to identify variations between them.
Methods
Data:
Preprocessing:
Analysis:
Discussion
The results did not show as strong a correlated as expected when compared to the literature. The results revealed a nearly equal split between the gardens cooler than their block groups compared to the gardens warmer than their block groups. The literature review discussed the efficacy of urban agriculture as a means to address the urban heat island effect. According to the literature a 10% increase in the vegetated surfaces of shade-providing trees with a high rate of evapotranspiration resulted in a decrease in temperature of 1°C in a radius of 100 meters (Mancebo, 2018). The results were not consistently aligned with the literature findings as there was a nearly equal split between the gardens cooler than their block groups compared to the gardens warmer than their block groups.
These results were surprising because there was nearly an equal split between the the gardens cooler than their block groups compared to the gardens warmer than their block groups. Just as there were block groups significantly warmer than the gardens, there were also gardens significantly warmer than their block groups. Figure 4 shows that the largest difference where a block group was warmer than a garden was 8℃. The largest difference where a garden was warmer than a block group was 7.5℃. A more refined set of surface temperature data may be needed to detect smaller variations between the gardens and the block groups.
Conclusion
The results show that not all community gardens were cooler than the block groups. Some changes can be recommended to make them more effective cooling agents. Research has found the implementation of deciduous trees to be effective for urban cooling. Additionally, larger green patches with high density edge are more efficient in decreasing the UHI than several smaller patches (Mancebo, 2018).
While this project examined the surface temperatures between community gardens and block groups, future research can include comparing other features such as immediately outside the garden, the neighborhood, and the county. Also, a collection of finer surface temperature data would provide more accurate results. Community garden surface temperatures can also be compared to one another. This may reveal what makes one garden more effective at cooling versus another.
References
Results
The majority of the gardens showed little to no surface temperature difference from the neighborhoods. As shown in Figure 1, the hottest gardens seem to be located in center city where there is generally less vegetation cover. These results can be compared to Figure 2 which represents the block group surface temperature. The temperatures of the block groups largely line up with the temperature of the gardens in Figure 1. The spatial analysis revealed that 140 out of 270 community gardens were recorded to have cooler surface temperatures than their surrounding census block groups. Furthermore, the average difference where community gardens are cooler than block groups is 1.63℃. The average difference where community gardens are warmer than block groups is-1.45℃. The largest difference where a block group was warmer than a garden was 8℃. The largest difference where a garden was warmer than a block group was 7.5℃.
Figure 1: Surface temperatures of individual community gardens throughout Philadelphia
Figure 2: Surface temperatures of each block group throughout Philadelphia
Figure 3: The variation in surface temperature between the block groups and corresponding gardens
Figure 4: The mean difference between the surface temperatures of the block groups and gardens
Acknowledgement
Thank you yo the GEV department for providing me with the tools to conduct this product and thank you to Dr. Kremer for your continued support and guidance throughout the process.