FIGURE 2
The IGN station recorded considerable Qnet increase (891 m³s-1) during the rainy season. In this case, it is essential emphasizing that positive Qnet has indicated water outflow inversely proportional to what happened during the dry season. ARA1 station recorded Qnet = 3,137 m³s-1 and maintained positive discharge values during the tidal cycle, even during the flood phase. On the other hand, URU2 station recorded maximum Qnet value = 3,688 m³s-1, whereas URU1 station reached maximum Qnet value of the same order (3,165 m³s-1). Qnet recorded for URU2 and URU1 in the rainy season were 6.7 and 4.1 times higher than the ones recorded in the dry period, respectively. This outcome suggests progressively increased loss of flow from Araguari River to Amazon River.
The dry season at URU1 section has significantly varied in comparison to the rainy season (Figure 2). However, this variation was even greater in comparison to results observed by Santos et al. (2018), who recorded Qnet = 897 m³s-1 during the rainy season (March 2015) (Figure 3). Thus, Qnet recorded in the present study, in May 2018, was approximately 353% higher than that of 3 years before. There was also considerable Qnetincrease of approximately 162% in IGN between two dry seasons (September 2014 and October 2017), although on a smaller scale (Figure 3). This outcome suggests dynamic and progressive hydrological and hydrosedimentary processes.