Author(s): Ismail Rifai, Sebastien Erpicum, Pierre Archambeau, Damien Violeau, Michel Pirotton, Benjamin Dewals, Kamal El Kadi Abderrezzak

Linked Author(s): Ismail Rifai

Keywords: Breach, floodplain plain confinement, fluvial dike, overtopping, subaqueous reconstruction

Abstract:

Fluvial dikes have been constructed as flood defense structures, but their failure may lead to casualties and major damages in protected areas. Flow overtopping is listed as the main cause of dike failure. An accurate assessment of the breach evolution is a prerequisite to a sound flood risk assessment and management. In contrast, the current knowledge of physical processes involved in fluvial dike failure by overtopping remains highly fragmented. This paper presents experimental tests on the breaching of homogenous sand-dikes in a fluvial configuration, i.e. the upstream flow is parallel to the longitudinal dike axis. Overtopping is initiated over a pilot notch at the dike crest. Experiments are performed for different inflow discharges in the main channel and under different levels of floodplain confinement. The transient evolution of the dike geometry is monitored using laser profilometry technique. The detailed reconstruction of the breach formation and expansion provides key insights into the mechanisms involved in the failure of fluvial dikes. Results show that the breach development differs highly from experiments disregarding the flow parallel to the dike axis (i.e. frontal configuration) as in the fluvial configuration where the breach develops mainly in the flow direction and the floodplain water level, strongly conditions the breach horizontal and vertical extents. (2634, 67, 276)

DOI:

Year: 2017