Diagram Tidal Wave in an Estuary

The displayed tidal wave is simplified as a linear wave (i.e. cosine wave) with a wave period \( T = 12h \), a wave length \( L = 360km \) and a wave height \( H = 3m \). In addition, a rectangular cross section of constant width is assumed throughout for simplification.

Under these boundary conditions, all calculated parameters result from a strictly geometrical consideration: With the knowledge of water as well as bed levels throughout the estuary, water depths and flow cross-sections can be determined for any location and at any time. This determines the volume of water in a section of defined length. By summing up these partial volumes of all sections above at two successive points in time, a rate of change and thus the current flow rate can be determined for any location. In addition, the current flow velocity can be determined with the aid of the flow cross-section. The calculated flow velocities result in the tidal current limit, as well as slack water at low tide and at high tide.

The field of Tides is part of the module Basic Coastal Engineering within the specialization Coastal and Ocean Engineering of the master programmes Civil and Environmental Engineering.