Initial loss estimates for tropical catchments of Australia

Rainfall based design flood estimation techniques are widely used in hydrological design and initial loss is an important input rainfall runoff models. Lack of research on initial loss in Queensland has led to the use of loss estimates from other states. Fifteen Queensland catchments were analysed and the results show that initial losses are much greater than Institute of Engineers recommended values. The derived initial loss values were positively related to rainfall duration but seem to lack seasonality. The antecedent precipitation indices appeared to be negatively related to initial loss values. The distribution of initial losses values can be modelled using a Beta distribution allowing stochastically variability of initial loss in joint probability related flood design modelling.