Stochastic modelling of river morphology: A case study

It is important to develop stochastic methods to predict river morphological processes. In this paper we presented considerations on the stochastic prediction of scour in a straight alluvial channel due to a constriction. Of all uncertainties involved, only the uncertainty in the future river discharge was taken into account. River morphological processes are nonlinear, which makes it difficult to apply stochastic methods. Therefore, we used a Monte Carlo method, despite the large computation time it takes. The results showed an uncertainty in the predicted bed lever of the same order as the mean bed level changes. The variations in time of the predicted statistical properties depended on the ratio between the duration of the discharge peak and the morphological time scale. The use of linearisation and constant discharges in stochastic modelling were discussed, which could probably be used to estimate statistical properties of morphological changes in a simplified way.