What is it about?

While designing certain high-risk structures (like nuclear power plants or flood defense systems), engineers and architects need to consider climatic influences. If the design of these structures fails, it might cause significant loss of human life and property and damage to the environment. Hence, the impact of extreme climate events on these structures needs to be assessed while planning their construction. Evaluation of rainfall and flooding was originally done using the concept of ‘maximum possible precipitation’ (MPP), which was the upper limit of rainfall that could occur in an area the building had to withstand. But, with climate change, more incidents of extreme occurrences have been recorded, calling for a modified evaluation method. The MPP was replaced by the ‘probable maximum precipitation’ (PMP) and, correspondingly, ‘probable maximum flood’ (PMF). These quantities would rarely be exceeded and so could be used as an accepted standard. In this study, authors examine the various methods being used to estimate the PMP and highlight ways to consider the effect of climate change and extreme events on these parameters.

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Why is it important?

PMP estimation can be done using hydrometeorological laws or statistics. The hydrometeorological methods observe extreme precipitation events and the associated meteorological conditions to calculate PMP. On the other hand, statistical methods can be used for areas or periods lacking hydrometeorological data. The authors found that climate change has significantly affected PMP and must be considered in designing and evaluating high-hazard infrastructure. They also provided suggestions to consider the effect of climate change while estimating PMP. KEY TAKEAWAY In conclusion, while the existing methods of estimating PMP are easily applied and widely used, they assume that certain calculated values (like that of rainfall) will not be exceeded. Climate change, however, has made atmospheric conditions unstable. We need to consider this and further develop safer PMP estimates.

Read the Original

This page is a summary of: PMP and Climate Variability and Change: A Review, Journal of Hydrologic Engineering, December 2020, American Society of Civil Engineers (ASCE), DOI: 10.1061/(asce)he.1943-5584.0002003.
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