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Identifying sources of uncertainty in groundwater recharge estimates using the biophysical model WAVES

Martin, M., Silberstein, R., Smettem, K.R.J. and Xu, C. (2008) Identifying sources of uncertainty in groundwater recharge estimates using the biophysical model WAVES. In: In: Lambert, Martin (Editor); Daniell, TM (Editor); Leonard, Michael (Editor). Proceedings of Water Down Under 2008, 14 - 17 April, Adelaide, SA, Australia pp. 2161-2169.

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Abstract

A biophysical model WAVES, developed by CSIRO, has recently been implemented as the modelling engine to provide recharge input and discharge output to an integrated regional groundwater model for the Perth region, namely, the Perth Regional Aquifer Modelling System (PRAMS). Application of the WAVES model over such a large area requires an extensive set of data that are not known with certainty. This paper describes a method based on the mean value first order reliability analysis method to determine the parameters that significantly affect uncertainty in the recharge estimates. The fraction of model output (recharge) variance (FOV) contributed by each basic parameter is determined using the sensitivity coefficients and uncertainty (measured by the variance or the coefficient of variation) of the model parameters. The FOV provides a quantitative means to rank the order of importance of parameters that affect the reliability of the recharge estimate and can be used to prioritise data collection to improve the estimate. Application of the proposed method to the local conditions on the Gnangara Mound found that the critical parameters for WAVES in the modelling framework of PRAMS are: rainfall, vegetation density measured by leaf area index, soil water holding capacity of the soil root zone, maximum root depth and maximum carbon assimilation rate.

Publication Type: Conference Paper
Publisher: Engineers Australia
URI: http://researchrepository.murdoch.edu.au/id/eprint/39519
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