Experiments of dam-break wave over a triangular bottom sill

The IMPACT project addressed the assessment and reduction of risks from extreme flooding caused by natural events or the failure of dams and flood defence structures. It was funded by the European Commission (EC), started in November 2001 and lasted for 3 years. This paper presents a dam-break flow experiment in a channel with a triangular bottom sill (the bump), that was part of the IMPACT benchmarking programme (WP3: flood propagation). This test case highlights some key issues linked to the propagation of dam-break waves on dry bed in the presence of a bed slope. Two types of measurement devices were used to obtain the evolution of the water depth. First, three water level gauges were used to obtain the time evolution of the water level at three different locations around the bump. Then, using high speed digital cameras, the flow was filmed through the glassy walls of the channel, resulting in a continuous experimental surface profile by combining the images acquired at different locations along the channel. An automated procedure was designed to measure the water depth from the digital images. This procedure has been successfully validated by comparison with the gauge records. Finally, all those measurements form a data set that can be used for the validation of numerical models.