Spatial dike breach: sediment surface topography using photogrammetry.

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Pierre-Jacques Frank, Willi H. Hager

Tuesday 30 june 2015

11:00 - 11:15h at Mississippi (level 1)

Themes: (T) Sediment management and morphodynamics, (ST) Sediment transport mechanisms and modelling

Parallel session: 5A. Sediment - Erosion

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River dikes prevent flooding of the adjoining environment during floods. Due to a lack of dike improvements and extreme floods, uncontrolled dike overtopping has caused large damages to populated and agricultural areas in the past. The dike breach process due to overtopping is still poorly understood, despite its importance for evacuation scenarios or fuse plug planning. Therefore, the previous laboratory research on the parameterization of plane dike breaching due to overtopping is extended to spatial breaches using novel laboratory experimentation. A test dike of homogenous non-cohesive sediment and of 0.20 m height, up- and downstream slopes of 1:2 and a crest length of 0.10 m was positioned in a channel 5.1 m long, 1 m wide and 0.6 m high. A pilot channel with a transversal slope of 1:2 is used for breach initiation at the front glass wall. To avoid dike failure due to seepage, a drainage is installed at the downstream dike toe. All tests are run with constant discharge. The dike breach surface is captured with the stereo-photogrammetric AICON measurement system, originally developed for measuring river bed elevations in physical models. To account for refraction effects due to the curved water surface during dike overtopping, the photogrammetric system was complemented with a fourth camera to record the flow depth along the channel side wall. In previous tests, the system accuracy and limitations were determined. The focus of the current research lies in the optimization of the test setup and first surface measurement results of spatial dike breach tests with mobile bed.