Spatio‐temporal reconstruction of avulsion history at the terminus of a modern dryland river system

Fluvial depositional architecture in an unconfined environment is governed by sediment dispersal across the alluvial plain through river-path switching avulsion. Documented inter-avulsion periodicity from modern rivers ranges tens to over a thousand years. In this study, quantitative spatio-temporal reconstruction of avulsion history presented non-vegetated and pristine Río Colorado dryland river system semi-arid Altiplano Basin (Bolivia), based on integrated analysis satellite imagery absolute age dating using optically stimulated luminescence, complemented with sedimentological geomorphological ground-truth data. This approach enables us reconstruct chronological order channel belts Colorado, determine recurrence time periodicity, identify mechanisms for flow path changes, present morphodynamic model evolution fluvial deposits environment. maximum timespan 12.71 ± 1.5 ka, successive avulsions created sheet interconnected deposits, consisting diverging juxtaposed ridges that formed aggradation point bars, crevasse splays, levees, floor. The show lateral onlap amalgamation as result repeated compensational stacking, whereby avoided positive alluvial-ridge relief its precursors. resultant morphology fan-shaped, convex-up surface area approximately 500 km2 observed thickness 3 m. results periods up 1.28 0.34 ka. A paucity activity around 2 ka BP, at present, interpreted low discharge related long-term dry El Niño Southern Oscillation circulation system. Each started sinuous, single-thread narrow belt, increased width sinuosity point-bar expansion rotation.