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Climate. Models aren't really specific enough to predict a new 500 year storm in a specific location. Those thresholds and definitions are based on the data re

Climate. Models aren't really specific enough to predict a new 500 year storm in a specific location. Those thresholds and definitions are based on the data record, and already encoded into regulation and a 100 years of construction. What we see instead is Regulators simply increasing the requirements from a X year storm to a 2X year storm, and leaving the definitions. This is what I have seen with the California building code

beerandt 2y ago
You're on the right track, but your framing is still off wrt how the engineering design process works. Assuming that designing for a 500-yr storm has anything to do with 'predicting what a 'future 500-yr storm' (or 25-yr or 100-yr) looks like is dead wrong. Irrelevant. The 'definitions' are not left alone, they are updated as time goes on. But with historical data, and they are not extrapolated/predicted out into the future. Engineers (PEs) design by taking known criteria and then applying probabilities and factors. They do not predict criteria. It's a subtle but important distinction. A 500yr event, by definition, is actually the one year probability of a 1/500 chance event. And it's up to the designing engineer to choose and state whatever the assumptions are that go into that. But a levee designed this year will use this years current 'storm definition' just as it uses this year's building code. Not a future one. (Sometimes the storm/ event definitions seem stale because things like flood maps might only get updated every few decades.)