5 CONCLUSIONS
Based on results, analyses and discussions, it was possible getting to
the following conclusions:
- 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.
- 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.
- 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.
- 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.