CATCHMENT CALIBRATION USING FRACTIONAL-FACTORIAL AND CENTRAL-COMPOSITE-DESIGNS-BASED RESPONSE-SURFACE

A new catchment calibration approach based on the fractional-factorial and central-composite designs (FFD-CCD) is presented in this paper. T he proposed method requires fewer simulations (almost 75% less) than t he approach based on the factorial and central-composite designs (FD-C CD) (Ibrahim and Liong 1992). However, the reduction in the number of simulations does not significantly affect the prediction accuracy of t he model. The calibration model has been applied to the Upper Bukit Ti mah catchment in Singapore. Results show that the prediction errors in peak flow and runoff volume in the proposed model are as small as tho se errors resulting from the original FD-CCD approach.