Spring tidal pumping
Spring tidal pumping is the increase in mean water level of a tidal basin in response to the larger tidal forcing of the spring tide. The main causes of spring tidal pumping are shown to be the rate of freshwater inflow and the variation of channel geometry over the tidal cycle, with the channel depth being especially important. A ratio of the tidal amplitude/entrance depth ao/hc is a good indicator for when spring tidal pumping will occur. For ao/hc>0.2 there is a strong likelihood that spring tidal pumping will occur, especially as the volume of freshwater inflow increases. The role of different combinations of harmonics in the ocean tide is shown.