How Cities Run Dry: Drivers of Water Shortages and Policy Implications

This briefing, authored by Dr. Tanya Petach of the Aspen Global Change Institute (AGCI), examines the drivers of declining lake and reservoir water storage globally. It highlights the distinction between anthropogenic causes, such as unsustainable water consumption, and climate-driven factors, such as increased evaporation and changing precipitation patterns, to argue for targeted policy interventions and adaptive management strategies to prevent urban 'Day Zero' scenarios.

• Global lake water storage has declined significantly over the last 30 years, with a study of nearly 2,000 lakes showing that 53 percent experienced significant declines between 1992 and 2020. The collective annual loss of freshwater lake storage during this period is equivalent to 17 times the volume of Lake Mead.
• The decline of lake water levels is driven by three primary factors: unsustainable water consumption, increasing temperatures and evaporation rates, and changes in precipitation patterns and runoff. Distinguishing between human-caused overuse and climate-driven decline allows for more targeted interventions, such as prioritizing sustainable withdrawal rates for overuse or diversification of water sources for climate-driven stress.
• Specific examples illustrate the different drivers of water loss: the Aral Sea has shrunk by 88 percent since 1920 primarily due to human overuse, while Lake Khyargas in Mongolia has declined due to rising evaporation fueled by temperature increases. Conversely, Lake Sevan in Armenia demonstrates that enforcing water conservation and withdrawal limits can increase lake storage in previously overused basins.
• Urban centers are increasingly vulnerable to 'Day Zero' scenarios—systemic collapses where taps run dry—as seen in recent water rationing in Bogotá, Colombia (affecting over 9 million people) and water cuts in Mexico City (affecting 22 million residents). Cape Town previously averted such a crisis between 2015 and 2017 by reducing water consumption to 50 percent of 2015 levels.
• To combat evaporation-driven losses, which are expected to increase global mean lake evaporation rates by 16 percent by 2100, innovative infrastructure is being used. For example, a floating photovoltaic array on the Passaúna reservoir in Brazil reduced evaporation by 60 percent.

APA

Petach, T. (2024). How Cities Run Dry: Drivers of Water Shortages and Policy Implications. Energy Innovation. https://energyinnovation.org/expert-voice/how-cities-run-dry-drivers-of-water-shortages-and-policy-implications/

Chicago

Petach, Tanya. How Cities Run Dry: Drivers of Water Shortages and Policy Implications. Energy Innovation, 2024. https://energyinnovation.org/expert-voice/how-cities-run-dry-drivers-of-water-shortages-and-policy-implications/.

Wikipedia

{{cite report |last1=Petach |first1=Tanya |title=How Cities Run Dry: Drivers of Water Shortages and Policy Implications |publisher=Energy Innovation |date=30 July 2024 |url=https://energyinnovation.org/expert-voice/how-cities-run-dry-drivers-of-water-shortages-and-policy-implications/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{petach2024how, author = {Petach, Tanya}, title = {{How Cities Run Dry: Drivers of Water Shortages and Policy Implications}}, institution = {Energy Innovation}, year = {2024}, month = jul, url = {https://energyinnovation.org/expert-voice/how-cities-run-dry-drivers-of-water-shortages-and-policy-implications/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }