Modeling Bridges in HEC-RAS 2D: Comparison with Flume Experiments

A set of experimental measurements with a physical model in a flume, measuring the head loss generated by different bridge geometries in steady and unsteady conditions, is used to test the performance of HEC-RAS 2D in modeling bridge hydraulics, a fundamental component of any flood study. After upscaling the experimental results according to Froude similarity, the numerical tests have explored the effects of the choice of the options offered by the HEC-RAS 2D software with the default value of the parameters and the obtainable improvement when the geometry of the bridges suggested a customized value of parameters. The numerical results show a very good match with the measured water elevation upstream of the bridges for almost all tested cases. The mean absolute percentage error obtained pooling all the steady test cases is less than 5%.