NET SEDIMENTS TRANSPORT PATHS BASED ON THREE GRAIN-SIZE TRENDS ANALYSIS PROGRAMS IN THE SOUTH SECTOR OF THE PARANAGUÁ ESTUARINE COMPLEX OUTLET DELTA - SOUTH BRAZIL

Abstract

This work presents the results of GSTA, GSTAST and TRANSVEC grain size trend analysis programs based in mean size, standard deviation and skewness parameters of bottom sediments at the south portion of the Paranaguá Estuarine Complex Outlet Delta. The longshore sediment transport is from southwest to northeast in the area, ruled by episodically high-energy frontal systems events. Consequently, the sediments are trapped by the hydraulic dam formed by tidal currents and the south part of the outlet is quite large that the north portion. Thus, an extended breaking wave field from 1.5 to 5 meters water depth named Galheta Bank is formed. Currents and wave action in this bank sediments cause spit formation that moves landward into the bay mouth. The result suggests that the trends generated by GSTA program fits with the bathymetry. They are according to the expectations in the southern and center sector of the area, but they are not in the NE and NW sectors. The TRANSVEC program identifies the transport path to the marginal channel of the delta and the tendency of this channel to export sediments during strong ebb tide currents in the NW sector, but the vectors also indicate SW preferential transport that contradicts field observations. The most consistent result was obtained by GSTAST program that generates empiric data and a significant test with 95% confidence before validating or not the resultant vectors. The eastern vectors reflect wave sediment transport on the Galheta bank, central vectors show deposition by longshore drift over the bay mouth delta and the west vectors are according with the deflection of the longshore currents caused by the sudden decrease of depth in the delta.