Curve Number Calibrations on 204 Australian Catchments

Abstract

The Australian water balance model (AWBM) is automatically calibrated to 204 data sets from the main stream-gauging network in Australia. This daily rainfall-runoff model calculates surface runoff and baseflow as separate components of runoff, and the curve number (CN) is calibrated to the surface runoff component in each data set. The catchment areas ranging from 52 to 1,970 km2 contain mixes of soils and vegetation, but the calibrated CN can be used in the catchment areas and surrounding regions. There was a distinct relationship between the median calibrated CN for average antecedent rainfall (CNII) value of each group of catchments and the mid latitude of the group with an increase of one in the median CNII for each one degree increase in latitude. The method has potential for providing a very large amount of surface runoff data for calibrating the CN from the 3,000 or so stream-gauging stations in Australia.