Bed morphology characterization of an anabranching bifurcation-confluence of the Solimões River, Brazil

The bathymetric position index (BPI) determines whether a DEM cell constitutes part of a positive or negative feature of a specified-size bathymetric neighborhood. It has been profusely used in marine geomorphology research (e.g. benthic mapping, seabed classification) in the last two decades. This contribution illustrate a BPI-based scheme to characterize broad-scale bedform structures that are present in anabranching tropical mega rivers. The scheme in question is applied to bathymetric observations from an anabranching structure associated to the Marchantaria island (~7 km upstream of Solimões-Negro confluence). Thus, a custom seven elementary classes describing bank and bed topographic structures was obtained. Subsequently, when coupled with an analysis of the variability of fine-scale bedforms features (i.e. ranging from small dunes to bars) by means of the Bedforms-ATM toolbox, the quantitative description of the bedform complexity is markedly extended.