This module estimates sub-catchment runoff hydrographs. Of the many estimating procedures available, including unit hydrographs, empirical formulae and other runoff routing algorithms, Laurenson's non-linear runoff routing method was adopted for XPRafts.
It offers the most flexible model to simulate both rural and urban catchments
It allows for non-linear response from catchments over a large range of event magnitudes
It considers time-area and sub-catchment shape
It offers an efficient mathematical procedure
Considerable work has been done to verify this model on Australian catchments and to date the results have been satisfactory over a varying range of catchments and rainfall events
Data for Laurenson's model consists of catchment area, slope, degree of urbanisation, loss rates and observed or design rainfall information. Only a limited treatment shall be given on the theory of Laurenson's model, as a comprehensive review is given in by Aitken (1975).