Uncertainty Analysis ofWater Surface Profile Computations in Rockfill Structures Using Fuzzy Probabilistic Method

Rockfill is one of the construction materials used in hydraulic structures. Water surface profile computations are required in the design and performance evaluation of many rockfill structures. In water surface profile computations in rockfill structures, some physical parameters cannot be accurately measured and are uncertain. Uncertainty analysis can be used to estimate the uncertainty in the output of a model due to uncertainty in its input parameters. In this study, uncertainty analysis of water surface profile computation in rockfill structures is conducted using a hybrid approach which is a fuzzy probabilistic method. This is done for Wilkins and Stephenson empirical equations and the results are compared with those of a physical model. Results indicate that the Stephenson equation shows a better agreement with the experimental data. Also, if fuzzy parameters are estimated properly, the Stephenson equation shows less uncertainty.