Modeling dispersion in complex open channel flows: Fuzzy calibration (2)

Part 1 of this study assessed the effectiveness of dispersion models based around random particle tracking (RPT) applied an overbank flow in the Flood Channel Facility at HR Wallingford. Several of the RPT models that were us ed predicted the mixing behaviour of the tracer in the complex channel flow to within an acceptable accuracy. If there is no uniqueness in the model s tructure which can be used to represent the true system to within the limit ations of the available observations, then this implies an inherent degree of ambiguity in our knowledge of the physically based model structure. This suggests that we should be less forthright in the optimisation of each ind ividual model structure, and perhaps investigate more of the parameter comb inations for each model which yield feasible simulations of the system. An alternative fuzzy calibration technique is introduced which avoids the opti misation process and takes account of uncertainties in the model structure, parameter sets and observed data in prediction.