The success of a catchment model is known to depend a great deal on th
e catchment-model calibration scheme applied to it. This paper present
s the application of a genetic algorithm (GA) in the search for the op
timal values of catchment calibration parameters. GA is linked to a wi
dely used catchment model, the storm water management model (SWMM), an
d applied to a catchment in Singapore of about 6.11 km(2) in size. Six
storms were considered: three for calibration and three for verificat
ion. The study shows that GA requires only a small number of catchment
-model simulations and yet yields relatively high peak-flow prediction
accuracy. The prediction error ranges from 0.045% to 7.265%.