Comparison study on computer simulations for bridge scour estimation

This paper compares the use of 1D and 2D hydraulic models for bridge scour prediction. Two representative computational software developed by Federal Highway Administration (FHWA), HEC-RAS and Flo2dh, are used as the benchmark comparison bases. The procedures for model construction and scour estimation are illustrated by developing simulation examples. The comparison shows that 1D model using HEC-RAS, while is easy to construction, does not account for the effects of flow disturbance due to hydraulic obstructions. These include the spatial variation of the alignment angle, which significantly affects the depth of scour prediction. Higher dimensional mode such as Flo2dh captures the effects of flow field distribution. It is however difficult to use and requires deliberations to run proper simulations. Further development of computational simulation and visualization technologies is necessary and will help place computer aided bridge scour simulations into the hands of practitioners.