FIGURE 7
Qss in URU1 was 1.7 times higher during the rainy season
than during the dry season; it reached 35,673 t tidal
cycle-1 (Figure 7B). On the other hand, mass balance
between the URU1 and URU2 stations has shown increased suspended solids
transport in the rainy season (approximately 72,309 t tidal
cycle-1) (Figure 7B). It may have happened because
erosion processes have greater capacity to remobilize sediments and
carry solids stored in flooded fields.
According to estimates, URU1 has captured 100% of solid discharge
coming from lower Araguari River during the dry season, lost 31% of
what was retained in the flooded fields and dumped 69% of
Qss coming from Araguari River into the Amazon River
(URU2 = 14,675 t tidal cycle-1) (Figure 7A). On the
other hand, URU1 received only 33% of Qss coming from
lower Araguari River, as well as other 67% of it coming from flooded
fields, and it totaled 100% of Qss coming from Araguari
River discharged into the Amazon River (URU2 = 107,982 t tidal
cycle-1) ( Figures 7B).
3.3 Physical-chemical water parameters
Kruskal-Wallis test has shown significant differences in water quality
for all 4 environmental factors (distance, location, seasonality and
tide), based on 11 physical-chemical parameters and on 17 hydrodynamic
parameters (p < 0.05). Multiple regression tests have shown
significant correlations of SSC and Qss(dependent) to other water quality and hydrodynamic variables (Tables 1
and 2). Results have indicated significant spatial-seasonal variation in
the investigated parameters and significant correlations between
different hydrodynamic and water quality parameters associated with
erosive processes.