FIGURE 3
With respect to water balance during the dry season, most of the flow
into Araguari River is blocked by the silting up of its former mouth,
follows through Urucurituba Channel and flows into Bailique archipelago,
in the Amazon River mouth. A second fraction of the flow - accumulated
in Igarapé Tabaco region - returns to URU1 during ebb (Figure 4A),
whereas during flood, it flows towards the old mouth and tends to spread
to the lake regions through an affluent (Igarapé Tabaco). This flow
leads to significant changes in water quality, such as salinization
processes (Cunha and Sternberg, 2018). A third fraction of it (220
m3s-1), which represents the
difference in flow between URU1 and URU2 stations, is diverted into the
floodplain (complex network of channels and branches in the floodplain).
Thus, the right bank of Urucurituba Channel is connected to
Gurijuba-Igarapé Novo Channel and, again, to Araguari River (Figures 1
and 4A) – it receives water inflow during the high tide.
Most water flowing into Urucurituba Channel (URU1) during the rainy
season comes from Araguari River. A second fraction of the flow heads
towards Igarapé Tabaco region and returns to URU1 during ebb, and it
indicates prevalence of fluvial discharge (ebb tide) in water balance.
Finally, a third fraction of the water flow, which was estimated at 523
m3s-1 (Figure 4B), comes from the
floodplain into Urucurituba Channel.
Thus, Urucurituba Channel, in URU1, assumingly captures 100% of
Araguari River flow during the dry season, loses 29% of this total
because it gets retained in the floodplain and dumps 71% of Araguari
discharge into the Amazon River (URU2 = 548
m3s-1) (Figure 4A). On the other
hand, URU1 receives 86% of direct flow coming from Araguari River anad
absorbs additional 14% coming from the floodplain during the rainy
season. It totals 100% of the discharge coming from Araguari River
flowing into the Amazon River (URU2 = 3,688
m3s-1) (Figure 4B).