Identification of improved rainfall-runoff models for an ephemeral low-yielding Australian catchment

The paper discusses how the conceptual rainfall-runoff model IHACRES (Identification of Hydrographs And Components from Rainfall, Evapotranspiration and Streamflow data) has been extended for application to ephemeral catchments. Such catchments normally operate on a delicate hydrological balance, which is quite often manifested by strong non-linearities in their runoff response, including cessation of flow during the Summer periods of the year. The standard IHACRES model has worked well in temperate, humid catchments, providing reliable predictions on independent streamflow data sets and encapsulating catchment response dynamics in a systematic way. Not surprisingly, however, it does not perform so well for dry climate, low yield catchments and it is necessary to include an additional nonlinear mechanism to account for the ephemeral nature of the discharge. The results of this extended model, when applied to an Australian benchmark catchment, demonstrate significant improvements in simulating runoff during the dry season when significant rainfall events produce little or no discharge.