A critical assessment of the performance of standard 2D flood models based on results of 3D URANS simulations

摘要

Evaluating the accuracy of 2D depth-averaged solvers to predict flood propagation in natural environments is one of the most important challenges to mitigate floods. This paper discusses the performance of SRH-2D, a standard 2D flood propagation solver in terms of predicted flood extent and depth-averaged velocity profiles in a complex bathymetry river reach for high flow conditions. The accuracy of the 2D solver is mainly evaluated based on comparison with results obtained using a 3D URANS two-phase flow model developed using the commercial software STAR-CCM+. The 2D model performance is evaluated for a steady-state test case. The domain contains a 7-km reach of the Iowa River near Iowa City and 2 river dams. Even though the SRH-2D depth-averaged velocities show the same pattern as the 3D depth-averaged results, the 2D model tends to underpredict the location and magnitude of the peak unit discharge inside the channel, especially in the regions where 3D effects are significant.