Estimating runoff in ungauged catchments from rainfall, PET and the AWBM model

Multiple linear regressions are used to relate average annual runoff to average annual rainfall and areal potential evapotranspiration (PET) using data from 213 catchments grouped according to location in six of the major Drainage Divisions of Australia. A method is presented for estimating daily runoff from daily rainfall data using the AWBM model, which self-calibrates its surface storage parameters to the estimate of average annual runoff from the regressions, and using default values for its baseflow parameters. Two-thirds of the estimates of average annual runoff were within ±25% of the actual value. The approach can also estimate satisfactorily the monthly and annual runoff series in many catchments, with the simulations being only slightly poorer than those obtained by directly calibrating the AWBM against recorded runoff.