Benefits and Limitations of Current Approaches to Whole of Catchment Modelling

Abstract: Developments in catchment modelling frameworks, such as the new WaterCAST tool developed by the eWater CRC, have improved the ability to model catchment management and land use changes at the whole of catchment scale. While these tools have given modellers greater flexibility in the approaches, algorithms and frameworks which can be applied to a particular catchment, this paper will examine these improvements through a number of case studies and discuss current benefits and limitations when modelling with the WaterCAST tool at this scale. In the application of catchment models, significant effort is focused on the prediction and calibration of hydrology, however we still have considerable limitations in terms of understanding and predicting hydrologic change through the application of catchment management activities, both in urban and rural land uses. Even at the fundamental level, our ability to discretise between different hydrologic responses driven by spatial characteristics (e.g. different vegetation types, soil characteristics, land management practices, slope etc) is still limited, due to both a lack of process understanding and the difficulty in obtaining sufficient data and at appropriate resolutions. While hydrologic modelling has seen considerable research effort, advances in the modelling of water quality have not progressed by a similar amount, and once again, data limitations may be the key cause of this