I’d be really grateful for any help you can give with this…..

I’ve been using this formula to calculate a river flood frequency curve for a series of growth factor values ‘xT’ :

xT = 1 +β/k {1-(T-1)-k} (k≠ 0)

The value of k is always between -1 and +1. However, when k < 0 the values on the y axis are then negative (indicating, in this case, a negative flow rate). There is no such thing as a negative flow rate in a river system and this is, presumably, corrected by the additional information:

- ∞ < x ≤ 1 + β/k if k > 0

1 + β/k ≤ x < ∞ if k < 0

i.e it is bounded above for k > 0

Unfortunately, I don’t understand what this means or how it impacts on the main formula. Any help would be very much appreciated.

Many thanks,

Garret

E-mail: garret@dalriadaltd.com