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Validation of a watershed model without calibration Richard M. Vogel

Summary: Validation of a watershed model without calibration
Richard M. Vogel
WaterSHED Center, Department of Civil and Environmental Engineering, Tufts University, Medford, Massachusetts, USA
A. Sankarasubramanian
International Research Institute for Climate Prediction, Lamont-Doherty Earth Observatory, Columbia University, Palisades,
New York, USA
Received 23 December 2002; revised 5 June 2003; accepted 22 July 2003; published 18 October 2003.
[1] Traditional approaches for the validation of watershed models focus on the ``goodness
of fit'' between model predictions and observations. It is possible for a watershed model
to exhibit a ``good'' fit, yet not accurately represent hydrologic processes; hence
``goodness of fit'' can be misleading. Instead, we introduce an approach which evaluates
the ability of a model to represent the observed covariance structure of the input (climate)
and output (streamflow) without ever calibrating the model. An advantage of this
approach is that it is not confounded by model error introduced during the calibration
process. We illustrate that once a watershed model is calibrated, the unavoidable model
error can cloud our ability to validate (or invalidate) the model. We emphasize that model
hypothesis testing (validation) should be performed prior to, and independent of, parameter
estimation (calibration), contrary to traditional practice in which watershed models are
usually validated after calibrating the model. Our approach is tested using two different
watershed models at a number of different watersheds in the United States. INDEX TERMS:


Source: Arumugam, Sankar - Department of Civil, Construction, and Environmental Engineering, North Carolina State University
Vogel, Richard M. - Department of Civil and Environmental Engineering, Tufts University


Collections: Engineering; Environmental Sciences and Ecology; Geosciences