Experimental and numerical validation of shallow water flow around a surcharging manhole

Numerical simulation of sewer overflow into a main free-surface flow is studied and validated with respect to experimental data. A physical model of a linked floodplain and sewer system is used to carry out measurements under steady state flow conditions, considering systematic increase in the sewer surcharge. The depth-averaged Shallow Water Equations (SWE) are employed to model floodplain flow, in which sewer overflow is accounted for as an extra source term contribution. A finite volume shock-capturing scheme is tailored to solve the SWE on a non-uniform 2D mesh according to the characteristics of physical model. Steady numerical simulations are achieved. Numerical results and experimental datasets are compared, in terms of flood maps and depth histories, around at the local outflow area. The agreement between the experimental and numerical results is acceptable overall; however, it varied depending on the intensity of sewer surcharge, and on the choice of downstream boundary conditions.