Abstract
Studies about the hydrodynamic behavior in the lower Amazon River remain scarce, despite their relevance and complexity, and the Water Residence Time (Rt) of this Amazonian estuary remains poorly unknown. Therefore, the present study aims to numerically simulate three seasonal Rt scenarios based on a calibrated hydrodynamic numerical model (SisbaHiA) applied to a representative stretch of the lower Amazon River. The following methodological steps were performed: (a) establishing experimental water flow in natural channels; (b) statistically test numerical predictions (tidal range cycles for different hydrologic periods); and (c) simulating velocity fields and water discharge associated with Rt numerical outputs of the hydrodynamic model varied from 14 ≤ Rt ≤ 22 days among different seasonal periods. This change has shown the significant influence of hydrologic period and geomorphological features on Rt. Rt, in its turn, has shown significant spatial heterogeneity, depending on location and stretch of the channels. Comparative analyses between simulated and experimental parameters evidenced statistical correlations higher than 0.9. We conclude that the generated Rt scenarios were consistent with other similar studies in the literature. Therefore, they depicted the applicability of the hydrodynamics to the conservation of the Amazonian aquatic ecosystem, as well as its relevance for biochemical and pollutant dispersion studies, which still remain scarce in the literature.
Highlights
The Amazon basin is the biggest and most important tropical watershed in the world
Company (Companhia das Docas de Santana-CDSA); and (c) computer simulation of hydrodynamics observed in March, May, August and November, and of water residence time (Rt) in May, August and November 2019
Overall Results Recorded for the Experimental Data: Santana and North-Macapá Channels
Summary
The Amazon basin is the biggest and most important tropical watershed in the world. It presents a vast plane encompassing a complex system of rivers, channels, lagoons and islands that heiconstantly change due to sedimentation processes and to the transportation of dissolved and particulate matter.Estimates have shown that this basin discharges ≈ 20% of fresh water into the oceans; its plume extendsWater 2020, 12, 660; doi:10.3390/w12030660 www.mdpi.com/journal/waterWater 2020, 12, 660 up to 1.39 × 106 km inwards of the North Atlantic Ocean. The Amazon basin is the biggest and most important tropical watershed in the world. It presents a vast plane encompassing a complex system of rivers, channels, lagoons and islands that heiconstantly change due to sedimentation processes and to the transportation of dissolved and particulate matter. Water 2020, 12, 660 up to 1.39 × 106 km inwards of the North Atlantic Ocean. It accounts for transporting nutrients, organic matter and approximately 1.2 × 109 tons of suspended sediments into the ocean [1]. Amapá State coast is subdivided into two sectors: estuarine coast (Amazonian) and oceanic coast (Atlantic). Erosion and accumulation rates estuarine coastal sector reach 55% and 45%, respectively [2]
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