SUSPENDED LOAD OF GUAÍBA FLUVIAL SYSTEM, RS, AND ITS TEMPORAL VARIABILITY
DOI:
https://doi.org/10.22456/1807-9806.35910Keywords:
sedimento em suspensão, descarga sólida em suspensão, rio GuaíbaAbstract
The suspended load of the Guaíba fluvial system and its temporal variability were assessed. A dataset was assembled gathering river discharge daily data from the main rivers that form the Guaíba (Jacuí, Sinos and Caí rivers), and water turbidity data from a water treatment plant of Water and Sewage Municipal Department (DMAE), recorded at 30 minutes interval. The turbidity data were converted to suspended sediment concentration (SSC) throughout calibration procedures with samples of suspended sediments from the Guaíba. The turbidity monitoring station was also validated for representativeness to the Guaíba waters, with synoptic sampling. The turbidity data were reduced do mean daily values. The function of the SSC (kg.m-3 ) as function of river discharge (Q, m3 .s-1) was built given the rating curve SSC(Q) = 0.0057 + 0.00450,2884 Q with r2 = 0,68. The suspended load was directly obtained by the product of river discharge and SSC. The results indicated that the suspended load varies considerably along the time, mainly during short period discharge peaks. The major ity of suspended load is carried with river discharge between 1,000 and 3,000 m3 .s-1 , representing 47.2% of the total. The averaged suspended load to Patos Lagoon for the 2003-2006 period was of the order of 1,1 x 106 t/yr, or, of about 400.000 m of sediments (2650 kg/m3 ) from the Guaíba's drainage basin towards the lagoon depositional sites, and further the continental shelf.
