A detailed review of long-term rainfall records from stations within Northern Australia has revealed strong characteristics of cyclic non-stationarity in annual totals with primary episodes persisting from a minimum of 10 years and up to a maximum of 80 years. The level of non-stationarity was found to be significant with totals alternating between +6% and -25% of the long-term average.
Ramifications of this rainfall characteristic are of great significance to engineering water management and related investigations principally on account of the observed episode persistence. That is, average rainfall conditions are seen to never prevail, with the rainfall being either greater or lower than average for extended periods.
Furthermore, when applied to catchment yield calculations the observed signature of rainfall non-stationarity was found to be significantly amplified with positive non-stationarity episodes having yields increased by approximately 55% above long-term average and those for negative non-stationarity episodes being approximately 10% lower.
A technique has been also developed to account for the effects of persistent rainfall non-stationarity in the forecasting of stored mine inventories using operational simulation water balance modelling. Details of this technique, including typical outcomes are also presented in the paper.