Recent sedimentation in an Amazon tidal tributary: Integrated analysis of morphology and sedimentology

摘要: Abstract The Xingu River is an important tributary of the Amazon River, contributing 5% its total water discharge. Nevertheless, it does not contribute substantially to sediment load. lower reach forms a ria, result Holocene sea-level rise. also classified as tidal river, with tides >1 m at confluence River. This study evaluated morphology and sedimentology area, correlating both hydrodynamics understand infilling process ria. area encompasses stretch ~160 km, between Xingu–Amazon narrowing fluvial channel. During season maximum sediment-discharge (i.e., Feb 2016), 109 bottom samples were collected. Eleven sampling sites re-sampled during minimum water-discharge period rivers Nov 2016). Jun 2018), additional water-level measurements undertaken simultaneously at several locations along ria was on basis bathymetric surveys Brazilian Navy (DHN). results show that has taken place from upstream downstream directions. From upstream, forming prominent bayhead delta. Xingu-Amazon confluence, have transported sediments into Ria. There central portion lake large cross-sectional where relatively small amounts muddy are accumulating in quiescent environment. Sands prevail lateral margins, wave action causes bluff erosion limits fine-sediment deposition. common delta areas. Results suggest input been reduced over time, likely reduction tidally driven flux which occurred gradual increase constriction floodplains prograde.