Deterministic Versus Stochastic Interpretation of Continuously Monitored Sewer Systems

An analysis has been made of the uncertainty of input parameters to deterministic models for sewer systems. The analysis reveals a very significant uncertainty, which can be decreased, but not eliminated and has to be considered for engineering application. Stochastic models have a potential for dealing with these uncertainties. Interpretations of hydraulic performance, model of daily variation and simple unit hydrographs are used for illustration. The development is to use grey box stochastic models, which combine the virtues of deterministic and stochastic features.