The present paper focuses on the numerical modelling in TELEMAC-3D of flood control areas with controlled reduced tide structures along the Scheldt estuary and coastal zone for the storm event of December 6th, 2013. A new culvert functionality was implemented in the code to better represent the hydrodynamics of the exchange of water between the Scheldt estuary and these flood control areas with controlled reduced tide. Existing source and sink terms included in the code were paired and used as a culvert. The theoretical background to represent the different kind of flows through the culvert was based on the work of Bodhaine (1968). Additionally different head loss coefficients were introduced according to different geometric features of the culverts. The implementation of these new structures inside the 3D numerical model was validated using measured water levels in the estuary and inside the flooding areas, and using discharges (in and out) through the culverts measured only for one full tidal cycle. For the storm surge only measured water levels were available and these were compared with modelled ones.