Development of a national, landuse-based water balance model for Australia

Australia currently has no nation-wide comprehensive and consistent information on the spatial and temporal relationships between rainfall, evapotranspiration, drainage to groundwater and runoff to rivers. To estimate this information a simple modelling approach utilising existing data was sought. A review of existing models and their data requirements led to the development of a steady state Geographic Information System (GIS) based method driven by long-term average climate data and high resolution land cover and land use data. Mean annual and mean monthly runoff, evapotranspiration and drainage were modelled. Runoff results were evaluated against other published values where available and found to generally compare favourably, except in arid river basins. The model parameterisation was refined by calibrating against 330 and 211 sub-basins for the annual and monthly models respectively.