Median grain sizes on riverbeds range from boulders in uplands to silt in lowlands; however, rivers with ~1–5mm diameter bed sediment are rare. This grain size gap also marks an abrupt transition between graveland sand-bedded reaches that is unlike any other part of the fluvial network. Abrupt gravel-sand transitions have been attributed to rapid breakdown or rapid transport of fine gravel, or ...

Using previously published data from flume studies, we test a new approach for quantifying the effects of sediment supply (i.e., bed material supply) on surface grain size of equilibrium gravel channels. Textural response to sediment supply is evaluated relative to a theoretical prediction of competent median grain size (D950). We find that surface median grain size (D50) varies inversely with ...

A new method for granulometric-parameter-based reconstruction of sediment-transport pathways is proposed and is termed P-GSTA (grain-size trend analysis using principal component analysis) herein. The main advantage of this method is its applicability to depositional environments involving mixed transport processes, for instance, fluvial, tidal, and wave-influenced environments. In the P-GSTA m...

Despite representing a key parameter when modelling morphology or sediment transport, surface sediments are often assumed homogenous, with grain size temporally constant. This contribution uses a 6-year data set of monthly sediment samples to quantify the observed variability in intertidal beach sands at four energetic, macrotidal locations (North Cornwall, UK). Changes in grain size and sortin...

A sediment geoacoustic parameter estimation technique is described which compares bottom returns, measured by a calibrated monostatic sonar oriented within 15 degrees of vertical and having a 10 degree-21 degree beamwidth, with an echo envelope model based on high-frequency (10-100 kHz) incoherent backscatter theory and sediment properties such as: mean grain size, strength, and exponent of the...