Comparison of a regional Monte Carlo Simulation Technique against ARR-RFFE 2015 Model for Eastern New South Wales

In this paper, a regionalised Monte Carlo Simulation Technique (MCST) has been developed and compared to Australian Rainfall and Runoff-Regional Flood Frequency Estimation (ARR-RFFE) 2015 Model (test version) and Probabilistic Rational Method (PRM) in ARR 1987 for eastern New South Wales (NSW). This part of NSW was selected due to its adequate pluviograph and stream gauging stations of acceptable quantity and quality to develop and test a regional (R) MCST. This paper uses data from 86 pluviograph stations and 6 catchments to derive regional distributions of various stochastic model inputs and parameters that are needed to apply a regional runoff routing model, i.e. rainfall complete storm duration (DCS), rainfall inter-event duration (IED), rainfall depth (intensity-frequency-duration, IFD), rainfall temporal pattern (TP), initial loss (IL), continuing loss (CL) and runoff routing model's storage delay parameter (k). Comparison of the RMCST results with ARR-RFFE 2015 Model has been carried out for eight independent test catchments. It has been found that the RMCST generally out-performs the ARR-RFFE 2015 Model and PRM. The RMCST shows a relative error of 42%, which are 46% and 61% for the ARR-RFFE 2015 Model and PRM, respectively. The developed RMCST can be applied at any arbitrary location in eastern NSW. The advantage of the new RMCST is that it gives the full design hydrograph, in which ARR-RFFE 2015 Model and PRM only give the peakflow estimation. Although the method and design data developed here are primarily applicable to eastern NSW, the method can be adapted to other Australian states.