Optimizing Investments in Alternative Water Infrastructure for Urban Food Production in Water Stressed Cities

Urban agriculture has significant potential to address food security and nutritional challenges in cities. However, water access for urban food production poses a major challenge in the face of climate change and growing global freshwater scarcity, particularly in arid and semi-arid areas. To support sustainable urban food production, this study focuses on a hybrid urban water system that integrates two important alternative water resources: a decentralized system of rainwater harvesting (RWH) and a centralized reclaimed water system. A new spatial optimization model is developed to identify the best investment strategy for deploying these two alternative water infrastructures to expand urban food production. The model is applied to the case study in Tucson, Arizona, a semi-arid city in U.S. Southwest, to address food deserts in the region. Results show that 72%–96% of the investment is allocated to rainwater tanks deployment across all investment scenarios, with the proportion of investment in rainwater harvesting increasing as total investment rises. However, rainwater contributes only about 18%–27% of the total food production. The results of our case study indicate that expanding the reclaimed water network is more effective for urban food production and is also more cost-efficient compared to implementing rainwater tanks. The new model can be applied to other regions, taking into account factors such as crop types, climate, soil conditions, infrastructure configurations, costs, and other site-specific variables. The study provides valuable insights for planning urban water systems that incorporate alternative water sources under different investment scenarios.