Given a rank for a particular flood event of 25 and a record of ...

[jazziefee]

Given a rank for a particular flood event of 25 and a record of 24 years duration, what is the recurrence
  interval for a flood of this size? What will be an ideal response?

Question 2

Why is a longer historical record of peak discharge preferred for a given river when determining the
  statistical recurrence interval for flood events? What will be an ideal response?

[pallen55]

Answer to Question 1

On the average, a flood of this size would be expected to occur once a year. This is calculated by
adding 1 to the duration of the record in years (24 + 1) and then dividing this result by the rank of the
event (25).

Answer to Question 2

Short records may not include less frequent large flood events. As a result, there is a danger of
underestimating the size of future events and their recurrence intervals.

[jazziefee]

Thanks for the timely response, appreciate it

[Chelseyj.hasty]

Excellent