A model is built up from the very instant a natural phenomena is explained. Such a model manifests itself initially only in the mind (perceptual model) (Abbot, 2002) which is based on education, field and work experience. Thus it comes as no surprise that a well educated engineer will propose or explain a process in a different manner to a statistician. This understanding will then be formalized into a conceptual model in the form of equations, and finally a procedural model that will run on a computer and provide quantitative predictions (Beven, 2001). The procedural model will be a combination of numerical implementations of hypotheses that can or cannot be tested individually (Beck, 1987) and that will be different from original conceptual hypothesis because of implementation approximations. Every model will be an incomplete representation of reality as a result of multiple sources of uncertainty.

References

Abbot, M.B., 2002. On definitions. Journal of Hydroinformatics, 4(2): 1-27.

Beck, M.B., 1987. Water-Quality Modeling - a Review of the Analysis of Uncertainty. Water Resources Research, 23(8): 1393-1442.

Beven, K.J., 2001. Rainfall-Runoff Modelling: The Primer. Wiley, New York.

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Risk and Uncertainty (Description and Definition)

We may distinguish the primary sources of uncertainty as follows: