Dam Break Sediment Transport- A Hydraulic and Coastal Engineering Study

Lalji, Ashita (2007). Dam Break Sediment Transport- A Hydraulic and Coastal Engineering Study Honours Thesis, School of Engineering, The University of Queensland.

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Author Lalji, Ashita
Thesis Title Dam Break Sediment Transport- A Hydraulic and Coastal Engineering Study
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 2007
Thesis type Honours Thesis
Supervisor Tom Baldock
Total pages 50
Language eng
Subjects 0905 Civil Engineering
Formatted abstract
The swash zone, characterised as the part of the beach intermittently exposed to atmosphere and water, plays an integral part in the overall evolution of beach fronts. Knowledge and understanding of the hydrodynamics associated with this zone is therefore imperative, however at present is relatively limited. This is a direct result of the complexities associated with obtaining accurate measurements in the field, as the swash zone is notorious for its high velocity flows and extremely shallow water depths.

The experimental research carried out in this project relies upon the similitude inherent between the infamous dam break wave problem and the swash solutions derived from non linear shallow water equations by Shen and Meyer (1963). The dam break model also is capable of modelling this intermittent dry/wet nature associated with the swash zone, as mentioned above. Experiments focus on three main aspects of swash cycle: the down rush component, bed shear stress measurements and maximum uprush run-up lengths. For all cases, various combinations of bed slope, initial water depth, reservoir lengths and bed roughness are examined.

AnuGA- a recently developed hydrodynamic modelling tool, was used to compare depth and velocity profiles with collected down rush data, for different values of Mannings n. It was found to model the flow regime quite accurately, with differences in friction values influenced by bed roughness. AnuGAs output was also employed with the shear stress equations, in order to draw comparisons with measured bed shear stress data. Greater magnitudes of peak shear stress were observed in the uprush cases as compared with the down rush cases, for similar depth and velocity characteristics.

Maximum run-up length values were measured and the average dimensionless run-up height calculated to be approximately 1.27. This was found to be much smaller than Peregrine & Williams (2001) proposed value of 2. Interestingly however, the obtained value is much closer to Morrisons (2006) findings of 1.05.

Keyword non linear shallow water equations

Document type: Thesis
Collection: UQ Theses (non-RHD) - UQ staff and students only
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Created: Wed, 08 Jul 2015, 16:12:34 EST by Asma Asrar Qureshi on behalf of Scholarly Communication and Digitisation Service