Graphing Recurrence Intervals (Continued)
There are two ways to present the horizontal
axis of this graph: either in standard form where the curve is
not straight, or as a logarithmic scale which converts the curve
to a straight line. Use the button below the graph on the left
to toggle back and from between the standard view, and the semilog
one (one axis is log and the other linear.).
It's important to keep in mind that this curve
is based on only 21 years of data! The standard graph extrapolates
the trend of the curve out to 30 years, and the semilog one extrapolates
(predicts) out to 100 years. This allows us to make predictions
about the size of the 100 year flood. Be sure to understand
that we are making a prediction about something that is based
on only a small amount of observations. The 100 year flood may
be larger or smaller than our prediction. Do you think it makes
any sense to make a prediction about the size of a 500 year
flooding event?
Use the graphs, drag on the curve (which will
help you read the graph), and answer the questions below.
