Rainfall inputs can be either historic events or design storms. Observed spatial and temporal variations in historic events can be catered for by entering different rainfall data for each sub-catchment, according to daily rainfall and pluviograph records.

Design storms are typically inputted as a dimensionless temporal pattern combined with average rainfall intensity for the particular duration storm.

Typical design storm temporal patterns can be taken from Australian Rainfall and Runoff (Institution of Engineers, Australia, 1987) or similar references. Design storms can be varied for each sub-catchment.