Quantifying the Thirst of Western American Cities
The 21st century will see both growing cities and dwindling freshwater supplies. Understanding how cities use water, determining what constitutes sustainable water consumption, and measuring the sustainability of water supplies will be crucial in managing urban water use in coming decades. The increasing capacity to engineer water resources has resulted in reliance on water from vast areas often far removed from cities where the water is consumed, allowing consumption and growth far beyond the limits of local natural systems. This study explores the water consumption of ten cities in the Western United States with a focus on the relationship of consumption to population size and density, as well as precipitation rates and local watershed size. It identifies and measures the abnormality of urban water consumption based on macroecological patterns of water consumption by other mammalian species, and spatially quantifies the extent to which cities have surpassed local watersheds’ ability to produce. In putting a figure on the magnitude of the mounting problem, this study identifies patterns crucial to helping policy-makers and urban planners gain a deeper understanding of the challenges and opportunities in planning for the future.