During severe storms the sea-level at the tide-gauge of Delfzijl in the northern part of the Netherlands, often shows significant oscillations. These oscillations can add up-to 30cm to the high-water level and current operational hydrodynamic models do not predict these. It is generally believed that these are harbour oscillations, caused by sudden fluctuations in air-pressure and wind-speed associated with an unstable stratosphere or cold-front. Since, these oscillations occur only part of the storm surges, this make prediction of high water very inaccurate at in the Ems. The aim of this project is to study possible oscillations in the Ems estuary with a hydrodynamic Delft3D model. Questions relate to the possible modes of the system and their frequencies. Also the potential to forecast the likelihood of the oscillations to occur for a particular storm is of great practical interest. This project requires Msc level experience in hydrodynamic modeling and some experience (or affinity) with Matlab for post-processing and comparing observations to model results.