Catchment modelling-a resource manager's perspective

Models are invaluable tools for resource management. Models help resource managers develop a shared conceptual understanding of complex natural systems, allow testing of management scenarios, predict outcomes of high risk and high cost environmental manipulations, and set priorities. Catchment modelling is a specialist field, and different modelling approaches are specialist areas in themselves. There are a plethora of models available that apply to integrated catchment management, from micro to landscape scales, from deterministic models to broad-brush models. Different philosophies abound; with some experts advocating top-down systems approaches and others who dismiss these as being too uncertain and based on opinion rather than fact. Even when the approach is agreed, experts may be at odds over which modelling product is superior and have a vested interest in their particular product. So, how does the resource manager obtain objective, independent technical advice on needs and applications, and then choose the best modelling approach? Model development can be onerous, expensive, time consuming, and often bewildering for the resource manager. It is also an iterative process where the true magnitude of the effort, time and data required is often not fully understood until well into the process. Resourcing can become problematic. This paper explores the dilemmas faced by resource managers who dare to venture down the path of catchment modelling and proposes ways to minimise the pain and maximise the gain.