On the Use of Shallow Water Equations in Hydraulics

Abstract

Shallow water equations are widely used in inundation analysis as they are known to be successful in computation of flood inundations over wide terrains. Flood propagation in between buildings in urban areas and flows around hydraulic structures such as bridges may not satisfy the assumptions of shallow flow and may display markedly more 3-Dimensional (3D) flow characteristics. However, shallow flow equations can be used for such 3D flows also to allow fast numerical solution and a useful output may be obtained In this study, shallow water equations are applied to flows with prominent 3D characteristicsand results are evaluated. Water depths and velocity field in horizontal plane were calculatedsatisfactorily, surface waves in supercritical flow involving shocks were described in detail.However, in flows passing around more than one obstruction, there is a cumulative increasein error in the computed water depths. In case of uniform flows with boundary layercharacteristics, velocity and bed shear stresses were predicted successfully using a suitableturbulence model.