Data of paper "Sediment Shape as a Proxy for Fluvial Processes A Factorial Analysis in the Yarlung Tsangpo Grand Canyon"

This study addresses the current lack of research linking particle shape characteristics with fluvial dynamics and sediment supply processes. Field investigations were conducted in the remote Yarlung Tsangpo Grand Canyon, spanning from the confluence of the Parlung Tsangpo and Layuequ to the vicinity of Dexing Township, with ten sampling sites established along the transect. Using digital image analysis, two-dimensional shape parameters were extracted from over 36,000 individual particles. Multivariate statistical techniques, including Principal Component Analysis (PCA) and Factor Analysis (FA), were applied to identify three physically meaningful composite factors. The spatial and sediment size dependent patterns of these factors revealed that: (a) coarser particles, relative to finer ones, exhibit reduced mobility and longer residence times within the channel. Prolonged exposure to hydraulic abrasion and inter-particle collisions leads to lower saturation but higher smoothness, while lithologically homogeneous coarse sediments display greater strength and a more equant morphology compared to finer fractions; (b) abundant sediment supply largely preserves source-derived particle shapes, whereas variations in fluvial conditions along the transect dominate shape modification. For example, confluences reduce flow velocity, promoting particle deposition and prolonged in-channel exposure, thereby enhancing smoothness. Higher smoothness observed in the mainstem relative to tributaries indicates more intense flow and faster abrasion in the main channel.This study established relationships between particle shape, fluvial processes, and sediment supply through field investigations, providing a reference for future research in sediment dynamics.