5 CONCLUSIONS
Based on results, analyses and discussions, it was possible getting to the following conclusions:
  1. Urucurituba Channel has captured 100% (768 m3s-1) of Araguari River flow during the dry season, retained 29% of this total in the floodplain and exported 71% (URU2 = 548 m3s-1) of Araguari River discharge into the Amazon River. URU1 station received 86% of Araguari River flow during the rainy season, as well as other 14% coming from the floodplain, which totaled 100% (URU2 = 3688 m3s-1) of Araguari discharge dumped into the Amazon River. This process has favored erosive events, as well as changes in Sss and water quality parameters.
  2. The complexity of the new drainage system has significantly influenced water balance, sediments and water quality; it changed depending on location, distance, seasonality and tidal phase and explained up to 93% of the variation in Ssc concentration at Araguari River mouth. However, there was greater influence of the energy of tides propagating towards ARA1 during the dry season, whereas the fluvial discharge of Araguari River during the rainy season was the main forcing tide capable of overcoming the influence of tides in the estuarine zone of Araguari River.
  3. The hypothesis that Urucurituba and Gurijuba-Igarapé Novo channels are mainly responsible for variations observed in SSC and water quality in Araguari River estuary, whose features change from clear to white water, was herein confirmed. It happened because Urucurituba Channel and the floodplain act as areas of intense erosion processes.
  4. The tidal effect hypothesis was partly rejected with respect to variations in DO and Sss parameters, but it influenced other physical-chemical water quality parameters that significantly varied among the six sampling stations (except for Twand Tair). This outcome has refuted the hypothesis of physical-chemical similarity between waters due to intense hydrodynamic mixing processes in those specific stations.
Despite the intense effort to assess water and suspended solids balance in the region, the present study should be expanded in the future by further experimental campaigns in order to confirm whether this phenomenon is a trend or just temporary.
DATA AVAILABILITY STATEMENT” in the main document.