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CRC PUBLICATIONS |
CLASS - Catchment Scale Multiple-Landuse Atmosphere Soil Water and Solute Transport Model
Narendra Kumar Tuteja,
Jai Vaze,
Brian Murphy,
Geoffrey Beale,
Publication Type:
Technical Report
This is a publication of the current CRC for Catchment Hydrology
CRC Program:
Landuse Impacts on Rivers
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Publication Keywords:
Land use
Catchment areas
Models
Soil water
Solutes
Transport
Water yield
Salinity
Salting
Geographic information systems
Water balance
Spatial distribution
Vegetation
Pastures
Hydrology
Recharge
Plant water relations
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Abstract / Summary:
Preface
Since the beginning of computer based hydrological models in the 1960s and 1970s, there has been much debate regarding the appropriate structure and level of complexity of models. This reached fever pitch in the late 1980s and early 1990s as the cost of computing power reduced dramatically and a new generation of models that provided information not only at catchment outlets, but also simulation of the spatial responses within the catchment. These are so called "process-based, distributed models" and the most complex of them are based on fundamental equations for the movement of water and solutes through porous media, hydraulic and hydrodynamic behaviour. They are characterised as "bottom-up" models where algorithms related to the myriad of processes that make up hydrological response are linked together, resulting in models with a very large number of parameters, many of which are "in principle" measurable but in practice can be difficult to define.
These models contrast with the "top-down" style of models that are conceptually simpler with fewer empirical parameters that are generally calibrated against observations, but are more limited in spatial detail and process representation. The modelling literature, particularly from the 1990s, includes many discussions on the philosophical, theoretical and practical advantages and disadvantages of the various approaches to modelling, with often quite polarised views.
In more recent times, there has been a wider acceptance of "horses for courses" - the need for a range of models of different complexity to meet the wide range of modelling applications and data availability. This technical report describes the modelling framework, CLASS, which is at the more complex end of the modelling spectrum, but where there has been a major effort made to exploit the ever-increasing range of available data for setting up and running the model. CLASS was developed by the New South Wales Department of Infrastructure, Planning and Natural Resources as an Associate Project of the CRC.
CLASS is a distributed, eco-hydrological modelling framework that deals with water and solute movement from hillslope to catchment scale. Considerable effort has been made in representing vegetation growth, as well as in the pathways that water takes from hillslope to stream. This capability enables detailed simulation of the effects of different management scenarios. CLASS includes user-friendly interfaces to assist the user in preparing the data needed for execution and testing. The science that underpins CLASS has been externally reviewed and is clearly described in this report.
Ultimately, CLASS will be incorporated into the Catchment Modelling Toolkit (www.toolkit.net.au) and will be one of a number of models of different complexity that represent water and solute movement. The CLASS modelling framework includes seven products that can be implemented at the hillslope scale. However, at the catchment scale CLASS is a computationally demanding modelling approach, and requires considerable skill to apply and interpret the model results, but is a powerful platform for detailed analysis and makes excellent use of the available data.
Rodger Grayson, Director
CRC for Catchment Hydrology
The report is available for downloading below. Printed copies can be purchased from the Centre Office for $27.50 per copy (includes 10% GST, and postage and handling in Australia).
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Centre Office:
CRC for Catchment Hydrology
Dept of Civil Engineering
Building 60
Monash University Vic 3800
Tel: +61 3 9905 2704
Fax: +61 3 9905 5033
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