Dynamics and seasonality of the middle sector of a macrotidal estuary

This study presents the results on the hydrodynamic evaluation of the middle sector of the Caete estuary, considering seasonal variations of rainfall and fluvial discharge, as well as neap-spring tidal cycle. Measuring campaigns were performed over 13 hours at spring and neap tides during 2011. There, cross-sectionally averaged current velocities and direction, water levels, salinity and suspended solid concentration (SSC) were monitored. The evaluated estuarine sector showed an asymmetric tidal pattern as expected, with higher current velocities during the ebb, although this tidal phase was persistently longer. The flood phase presented two discernible velocity peaks, especially during the spring tide, where the main peak occurs at the first half of the flood, as it flows landwards into the channel, and a secondary peak, as the large contiguous mangrove areas are flooded. Ebb currents were generally higher than during the flood. The SSC could be directly related to the current velocities, therefore with the resuspension process.