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Hydrology Research Vol 40 No 2-3 pp 261–272 © IWA Publishing 2009 doi:10.2166/nh.2009.085 Voyage without constellation: evaluating the performance of three uncalibrated process-oriented modelsK. Tominaga, J. Aherne, S. A. Watmough, M. Alveteg, B. J. Cosby, C. T. Driscoll and M. PoschEnvironmental and Life Sciences, Trent University, 1600 West Bank Drive, Peterborough K9J 7B8, Ontario, Canada E-mail: kojitominaga@trentu.caEnvironmental and Resource Studies, Trent University, 1600 West Bank Drive, Peterborough K9J 7B8, Ontario, Canada Department of Chemical Engineering, Lund University, P.O. Box 124, Lund SE-221 00, Sweden Environmental Sciences Department, University of Virginia, 291 McCormick Rd, Charlottesville 22904-4123, Virginia, USA Department of Civil and Environmental Engineering, Syracuse University, Syracuse 13244-1190, New York, USA Coordination Centre for Effects (CCE), PBL, PO Box 303, Bilthoven 3720 AH, The Netherlands ABSTRACT Three process-oriented dynamic acidification models were applied to a long-term monitoring site without calibration to evaluate the influence of model structural differences on simulation. The models were simplified to share as many commonalities as possible so that the main structural differences could be investigated. The models differed in sub-models for cation exchange, organic acids and acid anion speciation. All models were populated with ‘equivalent’ parameters by systematic input mapping. The influence of input variability was addressed through Monte Carlo parameter sampling. The three models behaved exactly the same for tracers (e.g. sulphate and chloride), indicating successful cross-parameterization of the models. Differences in model structure had an impact on some of the simulated chemical parameters. In particular, models using Gapon cation exchange simulated higher base saturation levels in the long run than their Gaines-Thomas counterparts, but simulated lower base cation concentration and acid neutralizing capacity in soil solution when acid deposition levels were high. Multiple-model evaluation frameworks as presented here allow for greater certainty in model predictions; ultimately, this type of framework should be employed when evaluating the impacts of future climate and environmental changes on soil and surface water hydrogeochemistry. Keywords: acidification; hydrogeochemistry; input mapping; model evaluation; Monte Carlo simulation; process-oriented models Publisher's Note: The pdf file of this paper was replaced on 12 May 2009 after correcting the following sentence in the Acknowledgement section: PAY-PER-VIEW: Buy this article for £24.00 (IWA MEMBER PRICE: £18.00) All prices include VAT. For customers where VAT should not be applied, the VAT amount will be removed upon payment |
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