Dune Stochastics in River Morphodynamics (short title: MORPHODUNAMICS) (TCB.6286)

In a densely populated and lowland country as the Netherlands, there is an increasing need for adequate tools that predict water levels in rivers during flood events. One of the main factors influencing water levels is the bed roughness, which is mainly determined by bedform dimensions and the composition of the riverbed surface. As a Ph.D. student, the applicant introduced a new way of modelling the vertical sorting of the riverbed material and thus the composition of the riverbed surface. The upper active part of the river bed is no longer represented by a discrete layer, but by a probability density function of active bed elevations. This promising new sediment continuity model is the first to describe the complex interaction among dune dimensions, sediment transport, vertical sorting, and river morphodynamics. By accounting for the stochastics of riverbed deformations, the study has opened up a new line of research.
The VENI grant will enable the applicant to further extend the sediment continuity model and make it applicable to realistic situations with free evolution of the mean bed level. This extension is required to make the model suitable for predictive river studies, such as the prediction of the effects of the river measures proposed by De Maaswerken for the river Meuse. The study involves new flume experiments in order to provide data for model validation. As a field casestudy, the model will be applied to the 1993 and 1995 floods in the river Waal. The model’s stochastic approach will enable proper modelling of the complex interaction between vertical sorting and river morphodynamics. As such, the study will improve existing tools for predicting morphological changes and water levels in rivers during flood events.

• S.F. Leclair and A. Blom (2005), A qualitative analysis of the distribution of bed-susrface elevation and the characteristics of associated deposits for subaqueous dunes, in Fluvial Sedimentology VII, Spec. Publ.. Int. Ass. Sediment., 35, M.D. Blum, S.B. Marriot and S.F. Leclair (eds.), p.121 – 134.

• A. Blom (2005). The impact of variability in dune dimensions on sediment sorting and morphodynamics. In River, Coastal and Estuarine Morphodynamics, RCEM 2005. Eds. G. Parker and M. Garcia. Taylor and Francis Group London, p. 873-881.

• Van der Mark, C.F., A. Blom, S.J.M.H. Hulscher, S.F. Leclair and D. Mohrig (2005). On modeling the variability of bedform dimensions. In River, Coastal and Estuarine Morphodynamics, RCEM 2005. Eds. G. Parker and M. Garcia. Taylor and Francis Group London, p. 831-841.

• Blom, A. and G. Parker (2004), Vertical sorting and the morphodynamics of bedform-dominated rivers: A modeling framework. J. Geophys. Res – Earth Surface. Res., 109, F02007, doi:.1029/2003JF000069

Presentations:

• River, Coastal and Estuarine Morphodynamics, RCEM 2005

Er zijn vier bedrijven en twee andere universiteiten bij dit project betrokken.