UK EA benchmark 4 (Water Module)

This page contains the test case 3 of the UK benchmark named Test 4 – Speed of flood propagation over an extended floodplain as well as its result generated by the Water Module in the Tygron Platform.

The objective of the test is to assess the package’s ability to simulate the celerity of propagation of a flood wave and predict transient velocities and depths at the leading edge of the advancing flood front. It is relevant to fluvial and coastal inundation resulting from breached embankments.

Description

This test is designed to simulate the rate of flood wave propagation over a 1000m x 2000m floodplain following a defence failure, Figure (a). The floodplain surface is horizontal, at elevation 0m. One inflow boundary condition will be used, simulating the failure of an embankment by breaching or overtopping, with a peak flow of 20 m 3 /s and time base of ~ 6 hours. The boundary condition is applied along a 20m line in the middle of the western side of the floodplain.

File:Topdown case4 ukbm

Figure (a): Modeled domain, showing the location of the 20m inflow, 6 output points, and possible 10 cm and 20 cm contour lines at time 1 hour (dashed) and 3 hours (solid).

File:Hydrograph case4 ukbm

Figure (b): Hydrograph applied as inflow boundary condition.

Boundary and initial condition

• Inflow boundary condition as shown in Figure (b). Table provided as part of dataset.
• All other boundaries are closed.
• Initial condition: Dry bed.

Parameter values

• Manning’s n: 0.05 (uniform)
• Model grid resolution: 5m (or ~80000 nodes in the area modelled)
• Time of end: the model is to be run until time t = 5 hours (if an alternative end time is used run times must be reported for t=5 hours)