Views
Any model is usually applied for a particular purpose and this purpose has to be recorded at the onset of the modelling exercise. This is important as, for example, a catchment model could be used for catchment management purposes or for understanding runoff-generation mechanisms. In the first instance, one would need to look at the variables which are important for the management, in the second, one may be interested only in variables influencing specific run-off generation processes. This would result in a different treatment of uncertainty in both cases. This includes the necessity of representing the mechanisms by the model for those aspects for which predictions under modified driving forces have to be made.