The need for this project arises from the concept that many drainage systems should be treated as systems rather than as a series of independent links with the design based on the concept that only the catchment area upstream of the point of interest needs to be considered. The currently recommended approach is based on the independent link approach and can be summarised as considering a series of storm bursts (or events) of different durations; the concept being that each storm burst will stress hydrologically an alternative part of the network. It is necessary that these different storm bursts be centred at alternative locations in the catchment which reflect that portion of the catchment generating the surface runoff that ultimately stresses the desired part of the catchment.

When continuous simulation approaches are used to generate flow sequences, it is not reasonable to expect that a series of storm events with the same spatial characteristics will provide a suitable sample of the spatial and temporal characteristics of storm events over a catchment. A pilot study reported by Leonard et al. (2005) presented and approach for including the spatial characteristics of storms in a multi-site generation of a rainfall series for the Sydney region. The suitability of this approach needs to be tested for other regions in the country.