Spring Tidal Pumping
Spring tidal pumping [STP] is the increase in mean water level of a tidal basin in responseto the larger tidal forcing of the spring tide. It is of particular importance in the inundation of tidalwetlands and in the flushing of estuaries with constricted entrances. Using a fourier expansionanalysis the principal factors causing STP are identified and quantified to first order. A previous paperused a 2-cell model based on the non-linear equations to explore the response of a small estuary toeach of these processes It was shown that the dominant cause of STP is the asymmetry in flowcaused by the variation of entrance channel depth over the tidal cycle. Other factors such as nonlinearresistance to flow and catchment flows have quite minor effects. Tidal data from Lake Conjola insouth east Australia are presented and analysed to demonstrate the role of the forcing tidalconstituents on STP and to illustrate the nature of this relationship as the entrance becomesprogressively restricted.