Geomorphology of fluvial deposits in the middle Tocantins River, eastern Amazon

This paper presents the geomorphological mapping at a 1:100,000 scale of fluvial deposits in the middle Tocantins River. The region preserves an important sedimentary archive of environmental changes of the Amazon and Cerrado biomes. Yet, the region is under influence of diverse anthropogenic activities, including planned or operational hydropower plants, and detailed geomorphological mapping is lacking. The mapping combined interpretation of surface geomorphic features, morphometric analysis, and field surveys. Three main geomorphic units were defined: (i) fluvial plain, (ii) fluvial terraces, and (iii) paleo-alluvial fans. The detailed mapping survey allowed a hierarchical organization of geomorphological units as well as their relative chronology of formation. Our results improve the understanding on the complex geomorphological processes which shape the current fluvial landscape. Specifically, improving the understanding of the Tocantins River floodplains is crucial to support conservation of flooded forests, sustainable use of natural resources and minimize socio-economic losses and damages.