Flooding of an area can be described mathematically and by the use of scale models. The different flow regimes can be discerned using the scale model and then these regimes can be modelled using mathematical relations. This mathematical description can then be used to design simulation computer code for such a flooding. The first part ofthis report describes the different flow regimes that can occur after a defence work fails. For all regimes estimations were done of the dependence ofthat regime on measured data and of calculation methods. This report shows that the dynamic terms in the mathematical hydraulic descriptions have the upper hand during the first parts of the flooding. Later friction terms become more important. The dynamic terms prove to be highly dependent on the correct implementation of the mathematical relation in the simulation computer code. Bottom friction depends more on correct data from the field. The second part of the report describes the verification of the capabilities of DELFT-FLS to simulate dynamic flow accurately. An improvement on the correct handling of straight closed bevelled boundaries was implemented. With the simulation of and comparison to a dam-break laboratory experiment the correct implementation of mathematical descriptions of flow is shown.Hydraulic EngineeringCivil Engineering and Geoscience