During the past centuries the tidal regime of the Scheldt estuary has seriously changed. This is due to different natural processes and human interventions in the estuary. An important question for the safety management in the Scheldt estuary is how the safety level changes on a long term, taking into account the historical and present human impacts (such as poldering, enlargement, etc.) and natural changes (sea level rise). An important aspect from viewpoint of safety management is the change of the high water levels during the coming decades. The changes in hydrodynamics and morphology of the estuary are related to each other. Within this report an analysis of both tidal and topo-bathymetric characteristics in the Lower Sea Scheldt since 1900 has been performed. The historical evolution of tidal parameters (high and low water levels, tidal range, duration of rising and falling, celerity of tidal wave) and topo-bathymetric parameters (hypsometric curves, channel volumes, volumes above intertidal areas) was investigated. For these tidal and topo-bathymetric characteristics several relationships were analysed. Long term evolutions show both similar as opposing trends for the investigated geographic sections (i.e. Parts of the estuary between water level stations) in the Lower Sea Scheldt.