A study on one-dimensional and discontinuous river flows with mobile beds

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Abstract.

This report focusses on discontinuous behaviour of hydraulics and morphology in rivers. The varying widths, slopes and bed levels that can be observed in mountain rivers can induce rapid, or discontinuous changes at a short length-scale. When present, these discontinuities have a major impact on changes in water and bed levels during floods.

In this study, existing theories on discontinuous solutions are applied to river flows with mobile beds. The propagation rate and stability of a discontinuity are analysed with the Lax shock-wave criterion. Effects of transitions in flow regime are described qualitatively by solving the Rankine-Hugoniot relations. Attention is paid to the effect of river bed mobility on discontinuous flows.

Acknowledgements

This report was in part supported by the EC Environment Research Programme (contract: EV5V-CT94-0462, Climatology and Natural Hazards), as a part of the FRIMAR project (Flooding Risks in Mountain Areas). The useful comments in the stimulating discussions with Prof. Dr. M. de Vries, Dr. Z.B Wang, Mr. A. van Mazijk and Mr. C.l. Sloff are gratefully acknowledged.

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