Wastewater reclamation holds a key for water sustainability in future urban development of Phoenix Metropolitan Area

Global water scarcity has been a growing concern among policy makers, researchers, and the general public. Rapid urbanization with more concentrated populations and emergent patterns of climate change (e.g., soaring temperatures and 19 years of drought) added uncertainty and complexity to the risk of water shortage for the Phoenix Metropolitan Area (PMA). In this study, we used a numerical simulation tool, termedWaterSim 5.0, to assess water sustainability indicators in PMA. Four hypothetical scenarios were evaluated, viz. desert, and green landscaping, as well as urban expansion into desert or agricultural lands, bracketing plausible paths of future development in the study area. Model outputs were evaluated using four sustainability indicators and policy controls: (1) groundwater use, (2) agricultural production, (3) personal water use, and (4) the 100-year adequate water supply metric for new population growth. All four scenarios were examined using both current (19%) and complete (100%) wastewater reclamation. We found that the rate of wastewater reuse drives a reduction in groundwater dependency in urban growth; urban-agriculture conversion provides a convenient means to enhance water sustainability. In the broader context, sustainable water planning strategies need to take into account other crucial environmental and socio-economic measures such as changes in thermal stress, agricultural production, and outdoor and rural lifestyles.