Trindade, W.; Pereira, L.C.C., and Vila-Concejo, A., 2016. Tidal modulation of moderate wave energy on a sandy tidal flat on the macrotidal Amazon littoral. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 487–491. Coconut Creek (Florida), ISSN 0749-0208.
The present study focusses on the Vila dos Pescadores, a tidal flat located at the mouth of the Caeté estuary in the northeast of the Brazilian state of Pará. The aim was to establish the interactions amongst climatological and hydrodynamic processes, as well as fluvial dischages under different conditions. Eight campaigns were undertaken between June 2012 and April 2014. Results show that during the dry season, winds were moderate to strong and blew mainly from the northeast, coinciding with migration of the Intertropical Convergence Zone (ITCZ) to the northern hemisphere. During the rainy season, when the ITCZ was moving through this Amazon sector, winds blew from different directions at varying speeds. Maximum local Hs values were recorded during the dry season, when wind speeds were stronger and the waves came from θ < 70°N. During this period, Hs values ranged from 0.0 m (low tide) to 1.3 m (high tide), associated with periods between 2–7 s. During low tides, the waves break on the sandbanks but as the tide elevation exceeds ∼1 m, the waves start to propagate over the sandbank and towards the shoreline. Precipitation levels also had a strong influence on this tidal flat, especially during the first half of the year, when increasing precipitation provoked a surge in the discharge of the Caeté River (with lower Hs values). Under different conditions of hydrodynamic energy (monthly and seasonal variation, neap and spring tides, equinox and solstice periods), wave energy was correlated strongly with the tidal elevation.