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.

本研究针对当前颗粒形态特征与河流动力及沉积物补给过程之间关联研究的空白展开。研究团队在偏远的雅鲁藏布大峡谷开展野外调研，调研范围覆盖帕隆藏布与拉月曲汇流口至德兴乡附近河段，并沿该断面设置10个采样点。借助数字图像分析技术，研究人员从超过36000个单颗粒中提取了二维形态参数。研究采用主成分分析（Principal Component Analysis，PCA）与因子分析（Factor Analysis，FA）等多元统计手段，识别出3个具备物理意义的复合因子。这些因子的空间分布及沉积物粒径依赖模式显示：(a) 相较于细颗粒，粗颗粒移动性更弱、在河道内的滞留时间更长。长期经受水力磨蚀与颗粒间碰撞作用，粗颗粒的磨蚀饱和度更低但表面光滑度更高；同时，岩性均一的粗粒沉积物相较于细粒组分，具有更强的结构强度与更趋近等轴的形态。(b) 充足的沉积物补给在很大程度上保留了物源区的颗粒形态特征，而断面沿线河流动力条件的变化则主导了颗粒形态的改造过程。例如，汇流区域会降低流速，促进颗粒沉积与河道内更长时间的滞留，进而提升颗粒表面光滑度。相较于支流，主河道内观测到的更高光滑度，反映出主河道内更强的水动力条件与更快的磨蚀速率。本研究通过野外调研建立了颗粒形态、河流过程与沉积物补给之间的关联，可为沉积物动力学领域的后续研究提供参考。