Help gratefully received for equation interpretation

**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