Spatially explicit land-energy-water future scenarios for cities: Guiding infrastructure transitions for urban sustainability

Cities drive the majority of global human resource consumption and serve as hubs of major infrastructural networks. To offset their resource demands, cities derive goods and resources from regions well outside urban boundaries inducing stress and impacts on distal ecosystems. As cities grow, these stressors are likely to increase, depending on choices about how resource demands will be addressed through new infrastructures; hence, city governance is extremely important to future global sustainability. However, to support effective decision-making and infrastructure transitions, developing tangible city-scale alternative future scenarios is needed. We present a methodology for developing plausible spatially explicit alternative futures for city infrastructures and discuss the tradeoffs in land, energy, carbon, and water resources among alternative future pathways. We first estimate future city populations and urban boundaries and characterize future land cover scenarios. Future population along with residential housing and commercial characteristics are used to estimate current and future electricity and water demand. We characterize the energysheds of cities, which then become the spatial template for designing future electricity production scenarios. Future electricity mixes and spatial distributions of power-plants provide wide-ranging tradeoffs in carbon reduction, water use reduction, and land usage. Additionally, we explore future alternatives for meeting water supply demands. Herein, we emphasize the importance of translating scenarios into physical on-the-ground relevance in order to ensure transparent communication among city-and utility-governance. Unless spatially explicit future infrastructure scenarios are provided, we believe city-level goals will become difficult to implement, or even worse, result in unintended consequences on regional natural resources.