This study at the Environmental Hydrology Laboratory at the University of Florida ranks 225 American cities with populations greater than 100,000 on fresh water availability and vulnerability.
For method details, see Padowski, J. C., and J. W. Jawitz, 2012. Water availability and vulnerability of 225 large cities in the United States, Water Resources Research, 48, W12529, doi:10.1029/2012WR012335.
Urban areas of population greater than 100,000 are ranked by fresh water availability based on liters per person per day. Absolute water availabilities have been normalized by scaling to the maximum value in the set. Vulnerability accounts for both mean water availability and variability about the mean (for example, drought frequency).
This method incorporates not only renewable water flows, but also the extracted, imported, and stored water that urban systems access through constructed infrastructure. These constructed sources represent important components of urban water supply, yet are typically excluded from water scarcity assessments. In this analysis, water availability is measured as the sum of the mean annual volume of water available to cities from both naturally-occurring and constructed sources. Natural availability is also constrained here by environmental limits on withdrawals. Urban water vulnerability is expressed as the susceptibility of those urban supplies under low-flow (drought-like) conditions.
High-ranking cities tend to be adjacent to very large lakes, such as the Great Lakes, and large rivers, such as the Mississippi or Columbia. For example, the highest-availability city (Duluth, MN) is the only US city on Lake Superior, the third-largest freshwater body in the world (by volume). The other Great Lakes have smaller volumes and are shared by more (and larger) cities. Low-ranking cities are often found in arid regions (for example Los Angeles and Las Vegas), have low storage per capita (for example Miami and Atlanta) or share sources with multiple other cities (for example Chicago and Tallahassee). This national, cross-cutting assessment required several assumptions for cases where limited data regarding source characterization or allocation exist (for example cities sharing the Great Lakes or large aquifers). Therefore, the current vulnerability assessments for an individual city should be considered in the context of the data available for each city. Population data in the table below are from the 2000 US Census.
