Dynamics of fortnightly water level variations along a tide-dominated estuary with negligible river discharge

Abstract. Observations indicate that the fortnightly fluctuations in mean amplitude of water level increase upstream direction along lower half a tide-dominated estuary (the Guadiana Estuary), with negligible river discharge, but remain constant upstream. Analytical solutions reproducing semi-diurnal wave propagation shows this pattern results from reflection effects at head. The phase difference between velocity and elevation increases mouth to head (where has standing nature) as timing high low levels come progressively closer slack water. Thus, tidal (flood–ebb) asymmetry discharge is reduced direction. It becomes upper sea remains despite increased friction due shoaling. flat significant portion an suggest character and, thus, propagating Details analytical model show changes depth or length semi-arid estuaries, particular for macrotidal locations, affect tide mass transport inundation regime. This potential impacts on estuarine environment terms ecosystem management.