Fiction and reality in the modelling world - Balance between simplicity and complexity, calibration and identifiability, verification and falsification

Where is the balance between simplicity and complexity in model prediction of urban drainage structures? The calibration/verification approach to testing of model performance gives an exaggerated sense of certainty. Frequently, the model structure and the parameters are not identifiable by calibration/verification on the basis of the data series available, which generates elements of sheer guessing - unless the universality of the model is be based on induction, i.e. experience from the sum of all previous investigations.

There is a need to deal more explicitly with uncertainty and to incorporate that in the design, operation and control of urban drainage structures. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.