  In this paper we propose a model for a sewer network coupled to surface flow
and investigate it numerically. In particular, we present a new model for the
manholes in storm sewer systems. It is derived using the balance of the total
energy in the complete network. The resulting system of equations contains,
aside from hyperbolic conservation laws for the sewer network and algebraic
relations for the coupling conditions, a system of ODEs governing the flow in
the manholes. The manholes provide natural points for the interaction of the
sewer system and the run off on the urban surface modelled by shallow water
equations. Finally, a numerical method for the coupled system is presented. In
several numerical tests we study the influence of the manhole model on the
sewer system and the coupling with 2D surface flow.
