National Academies unveils strategy to modernize probable maximum precipitation estimates

Water gushes from the Oroville Dam Spillway in February 2017. Credit: NOAA

For more than 75 years, high-hazard structures in the United States, including dams and nuclear power plants, have been engineered to withstand floods resulting from the most unlikely but possible precipitation, termed Probable Maximum Precipitation or PMP.

More than 16,000 high-hazard dams and 50 nuclear power plants are located in the United States, many of which are approaching or exceeding their design lifetime. Failure of any one of these structures will likely result in loss of life and could impose significant economic losses and widespread environmental damage.

While engineers continue to rely on PMP estimates when designing these large, critical facilities, the estimates themselves and the science behind them are based on outdated work. As climate change continues to supercharge storms, including rainfall amounts, that threaten existing infrastructure, there’s an urgent need to modernize PMP estimates and improve the science behind them, according to a new report by the National Academy of Sciences, Engineering and Medicine.