An Examination of A Random Cascade Model for Disaggregating Daily Rainfall Data (Technical Note)

Short time interval rainfall data (e.g. hourly data) serve as inputs to a range of flood and pollution transport models. However, they are not usually available. Due to availability of daily data as measured values, in this study an attempt is made to examine the suitability of a random cascade model for transformation of observed daily rainfall data measured at the rain gauge station situated on the Amameh catchment, north of Tehran, Iran. A random cascade model was proposed for the first time by Olsson (1998). The cascade model presented here is based on exact conservation of rainfall volume together with the rainfall seasonality. Having applied this model to the data measured with the mentioned rain gauge, 45-minute data were simulated and compared with its corresponding measured data for the same period of daily data. It was observed that the modelling procedure employed and used in this study can simulate the 45-minute peak values much better that the previous models such as the Olsson one. The potential for the better estimation of peak discharges is, therefore, has the potentiality to be used in storm design purpose as far as the application of rainfall-runoff models for flood estimation are concerned.