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CRC PUBLICATIONS |
Testing In-class Variability of Groundwater Systems: Local Upland Systems
Cuan Petheram,
Chris Smitt,
Glen Walker,
Mat Gilfedder
Publication Type:
Technical Report
This publication is hosted by the CRC for Catchment Hydrology
CRC Program:
Landuse Impacts on Rivers
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Publication Keywords:
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Abstract / Summary:
Testing In-class Variability of Groundwater Systems: Local Upland Systems
Executive Summary
The objective of this report is to partially assess the extent information can be transferred between hydrogeologically similar catchments, by investigating in detail one set of similar catchments.
The utility of the National Catchment Classification (Coram 1998) for transferring information between catchments of the same type is being assessed for Local Type III groundwater systems-deeply weathered, fractured rock aquifer (Coram 1998). This model was chosen because of its prominence in salinised regions in south-eastern Australia. Catchments of this type often occur on shallow slopes on the inland foothills of the Great Dividing Range in New South Wales and Victoria, from crystalline rock that has undergone deep weathering (Coram 1998).
Five catchments were compared-Narroonda, Popes (South Australia), Burkes Flat, Kamarooka (Victoria), and Wattle Retreat (New South Wales). These catchments were chosen because they have been studied in relatively high detail and they exhibit processes leading to salinisation similar to those proposed by the Local Type III model. These catchments encompass a wide variety of scales, gradients, and climatic zones.
The extent to which information can be transferred between Local Type III catchments was tested within a modelling framework. The five catchments were modelled using FLOWTUBE. Catchment parameter values, catchment response to incremental reductions in recharge and the dimensionless similarity of the catchments were compared. The catchment responses to incremental reductions in recharge were reasonably similar. Due to the wide variety of sizes, shapes, gradients, climates and geographic locations of the catchments tested, it is expected that poorly documented catchments of the same type will respond in a similar manner.
The results suggest that there is a considerable range in parameter values but that this is smaller than the range for all aquifer types. However, given the sensitivity of the models to transmissivity and specific yield, the range in values was too high to allow the transfer of 'averaged' values to other hydrogeologically similar catchments with confidence. Evaluation of a dimensionless similarity parameter (G) for each of the five catchments indicates that the parameters, transmissivity, specific yield, length and head may be inter-related. The implications of this are that: 1. the range in catchment responses might not be as great as suggested by standard sensitivity analysis studies 2. surrogate parameters may exist, which would enable aquifer parameters to be transferred to other hydrogeologically similar catchments with greater confidence.
This report is available for downloading (see below).
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Centre Office:
CRC for Catchment Hydrology
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