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).