Review of soil water models and their applications in Australia

Agriculture is the highest consumer of water resources in Australia. Soil water models play a vital role in agriculture in terms of estimating water use, water allocation and current water status at a given scale. This paper reviews widely-used soil water models developed in Australia over the last three to four decades that have been used to simulate soil water status at various temporal and spatial scales. These models are categorised in terms of their complexity. This paper provides an overview of soil water models and the basic modelling techniques employed by each model. Considerable emphasis is given to matching existing data availability with input data requirements for each model to identify the limitations of model application in terms of data availability. A comprehensive review of the application of soil water models is also given, supported by assessments of individual model performance. The limitations and assumptions made under various approaches to soil water modelling are subsequently examined. Research and policy agencies are focusing more and more on incorporating temporal models into spatial modelling frameworks for natural resources and water management purposes. These are consequently being used much more in the process of policy development. Complex models, whose wide-range application is often hampered by a lack of specific data, should have their processes simplified in order to be accommodated into spatial frameworks where appropriate. Biophysical processes within simple models should consider new data sources and understanding so as to gain more accurate predictions.