Theme 8-13-A new approach to extending stage- discharge relations.

Abstract

The gradex idea suggests that at large recurrence intervals the rainfall and flood frequency relations for a basin should be parallel. If this idea is correct it can be used to define the high flow part of stage-discharge relations for basins where actual flow measurements have not been obtained. The idea is tested on some Australian basins for which high-flow measurements are available and it gives good results. Examples are given of application of the method to data for other basins where only low-flow discharge measurements have been made, and the stage-discharge relations are defined for these basins up to the largest observed floods.