How can new data affect the flood frequency curve?

Answer 1

Well, if the curves are based on real data and data is diferent than the norm I would expect that the curve would skew because of the new data. I don't mean to be sarcastic, but isn't that obvious ?

Answer 2

Actually, using the extreme value analysis statistical tools most typically used, new data won't necessarily affect the "flood frequency curve" at all. Typically, such predictive data analysis tools such as the FIRM (Flood Insurance Rate Map) have changed because of a difference in computational methodology rather than new data.

In other words, you can take the same data but use a different method of computation to come up with a modified prediction. Even the addition of new extremes in the observed data may not cause the statistical prediction to vary much.