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.