Optimizing the co-benefits of food desert and urban heat mitigation through community garden planning

Urban community gardens can reduce food insecurity and serve as green spaces alleviating extreme temperatures. Such co-benefit synergy may prove especially significant for arid-land metropolises. Despite these synergistic roles, planning for community gardens is largely undertaken in an ad-hoc manner. To date, few studies have addressed the full potential (co-benefits) of developing urban vacant land into community garden-green spaces. We addressed this in a spatially-optimized way, developing a model seeking to mitigate food desert and urban heat, and applied it to the fast sprawling Phoenix metro-area, Arizona (USA). Examining more than 5,000 vacant parcels for potential garden-green spaces, we found that the optimal number and locations of community gardens needed for different mitigation goals can vary significantly. In the Phoenix metro-area, the gardens required for extreme heat mitigation is about twice the number for food desert mitigation because high-temperature areas are more prevalent and expansive in semi-arid desert environment compared to the relatively small number low income, food desert areas. Furthermore, we found that the existing 76 community gardens were mostly clustered around urban cores, leaving two-thirds of the metro-area underserved. If sited in a spatially-optimized way, the co-benefits gained from the 76 gardens could be doubled, and covering more high-need neighborhoods. Integrating fine-scale vacant parcel data, our model identified high potential community garden-greening sites in priority neighborhoods with a precision not capable in conventional planning methods. Our findings demonstrate that spatially-optimized planning is of particular importance to avoid clustering of community gardens and ensure more equal access to local food and outdoor cooling benefits.