Abstract
Bedload sediment transport is a fundamental parameter controlling geomorphic processes in alluvial rivers. Direct measurement in modern rivers is labor intensive, typically cost prohibitive, and often dangerous. In addition, few reliable methods exist for estimating bedload fluxes from ancient fluvial strata. In this paper, we present a model for estimating bedload transport rates from modern sand-bed fluvial systems and ancient fluvial sandstones using substitutions into the bedform-bedload equation. This is enabled by a newly defined empirical relationship between characteristic bedform migration rate and reach slope in normal-flow reaches. For modern rivers, this slope-velocity relationship is combined with published relationships for bedform scales to allow remote estimation of bedload flux. In stratigraphic applications, the slope-velocity model is combined with relationships for bedform scale from cross-set thickness and for paleoslope from barform height and grain size to enable estimation of ancient bedload. The modern application is evaluated using bedload and bedform data from a single survey in the North Loup River near Taylor, Nebraska, USA. The stratigraphic application is demonstrated using outcrop data from the Jurassic Kayenta Formation in Colorado National Monument, Colorado, USA. These two applications yield approximately order-of-magnitude total uncertainty (95% interval) in mean bedload flux estimates.
