ESTIMATION OF RECHARGE AND RUNOFF VOLUMES FROM UNGAUGED CATCHMENTS INEASTERN AUSTRALIA

A model has been developed to estimate runoff volumes from generally a vailable geophysical data. Most of the hydrological processes are mode lled in a realistic manner and the model needs only one fitting parame ter. Input to the model consists of monthly rainfall, evaporation and parameters. In the model, rainfall is partitioned, depending on soil w ater status, into soil water storage, groundwater recharge and surface runoff. Surface runoff and baseflow are separate outputs of the model and equal emphasis has been placed on estimating each of these flow c omponents. To do this a technique has been developed for estimating re charge. The model has been shown to reproduce observed monthly flows i n eastern Australian streams very well, both on catchments used to cal ibrate the model and in independent tests where it was used without an y local calibration data. This ability to provide good estimates of vo lumes of flow on ungauged catchments with very modest requirements for input data means the model could find wide application. The evidence of accurate estimation of runoff volumes in an independent test in a w ide range of climatic and geophysical environments is suggested to res ult from the physical realism of the model.