Effect of Rheology on Flood Wave Propagation Due to Ash Dyke Failure

Flood wave propagation is simulated due to a hypothetical ash dyke failure, in this work. Effect of breach parameters, bed roughness, and rheological parameters on the propagated flood is studied. For the cases considered, maximum flood depth at a downstream location (1.5 km from ash dyke) increases by approximately 10 per cent, when the breach width is doubled. However, the maximum flood depth is increased by 25 percent when the breach depth is doubled. It is found that the breach time and bed-roughness do not affect the results significantly. Simulated results suggest that viscosity has insignificant effect on flood wave propagation. However, both specific gravity and shear stress have a strong bearing on the results. A 50 per cent increase in the specific gravity results in 15 per cent increase in maximum flow depth. Similarly, the maximum flow depth is increased by 30 per cent when shear stress is doubled.