Estimating flow duration curves in perennial and ephemeral catchments using a disaggregated approach

Abstract

The authors proposed a methodology for estimating flow duration curves (FDC) for perennial and ephemeral catchments in islands using a disaggregated approach. The proposed method is approached statistically and uses no complex parameters in order to reduce uncertainty and retain simplicity. Firstly, the FDC was disaggregated into three parts (high, middle and low) and, for the purpose of this study, it focusses on the low flow section. Initially, the mean monthly flow was used for estimating runoff in both types of catchments. The results show the mean monthly flow provided proper estimates in the perennial catchments, but for the ephemeral catchments the estimates were substandard. Therefore, a different approach using climate indices such as aridity and a precipitation index was used in a generalized regression equation. The results show the majority of the ephemeral catchments responded properly to the climate indices indicating climate as a major controlling factor at the lower end of the FDC.