Sensitivity Analysis of Physically-Based Rainfall / Runoff Models

Abstract

The aim of this section is to increase the awareness of the actual physical processes occurring on the catchment surface and of the capabilities of models to represent them. Some users of advanced simulation models have experience with those approaches which had been used before computers were introduced. Those approaches are characterised by many oversimplifications and the use of fixed (constant) model parameters and fixed input conditions. Examples of elements of these approaches are such concepts as the “design storm” of a prescribed shape, unit hydrograph, time of concentration, or fixed runoff coefficients, which are built into conceptual models, but will not be dealt with here. When the users are not aware of the model capabilities, advantages of modern computer programs in running several alternative solutions are often not fully exploited. In the application of a software package in the analysis and design of storm drainage networks, one of the important steps is the training of users in understanding the physical background of the rainfall/runoff processes and the hypotheses built into the model, as well as in mastering the features of a particular model in performing the sensitivity analysis.