The provided text outlines the 2019 updates to Australian Rainfall and Runoff (ARR), specifically focusing on Book 8, which addresses the estimation of very rare to extreme floods. It defines three distinct event classes—rare, very rare, and extreme—based on their Annual Exceedance Probability (AEP) and the reliability of available data. The guide details various rainfall-based simulation methods, including Monte Carlo and ensemble event approaches, to transform design rainfalls into unbiased flood estimates. Significant emphasis is placed on joint probability analysis, which accounts for variables like seasonal patterns, initial reservoir levels, and con ...