Abstract
ABSTRACT Understanding the hydrosedimentological dynamics of tropical rivers is a challenge in the Amazon due to its remote and difficult-to-access areas. This study was based on data collected from 16 hydrosedimentological control sections in the 6 subbasins that make up the Itacaiúnas River Watershed (IRW), with 4 annual campaigns (high water levels, rising water levels, falling water levels, low water levels) between 2015 and 2019, with the aim of constructing and comparing sediment rating curves and sediment yield. The data at the mouth of the IRW revealed that the rainy season is responsible for 93% of liquid discharges (Q) with an average of 1460.88 m3/s and for 98% of suspended sediment discharges (SSQ) with an average of 5864.15 tons/day. Suspended sediment concentrations (SSCs) are low to moderate (50 to 150 mg/l). The curves encompassing all the data showed R2 values (0.92 to 0.99) greater than the curves with only the values of the rainy or dry season, indicating a good fit of the power equation to the SSQ and Q data for all sections studied. Higher values of coefficients a and b show areas of greater sediment production and deforestation, as well as areas with new sources of sediment and preserved forest.
Highlights
Understanding the dynamics of hydrosedimentological processes in watersheds is critical for decision-making and supports management planning for the rational use of natural resources (Vestena, 2009)
The present study evaluates the hydrosedimentological dynamics of the Itacaiúnas River Watershed (IRW) in 16 control sections
The results of streamflow, suspended sediment concentration and discharge and the sediment rating curves are first presented by subbasins and discussed considering the land use and other characteristics of each area
Summary
Understanding the dynamics of hydrosedimentological processes in watersheds is critical for decision-making and supports management planning for the rational use of natural resources (Vestena, 2009). The sediment yield of a watershed depends on its natural characteristics, such as topography, soil type, land use and cover, and rainfall amount and intensity (Santos, 2015), as well as anthropogenic factors. These factors affect the amount of sediments generated by bank and channel erosion, the distances traveled by the sediments, the storage/mobilization of available sediments, and the sedimentation rate (Williams, 1989; Reid et al, 1997; Vestena, 2009). On average, may account for 70 to 95% of the total solid discharge, depending on the position of the watercourse cross-section and other factors (Carvalho et al, 2000)
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