Experimental Investigation of Cluster Bed-Form Formation Over Uniform Sediment

Abstract

Problem statement: Cluster microforms are a type of small scale bed-form found in the surface layer of some gravel bed rivers. These bed-forms are comprised of discrete, organized groupings of particles that sit above the average elevation of the surrounding bed. As part of the structural organization of the bed, clusters are believed to impact the local dynamics of the fluvial system through the feedback process involving the flow field, entrainable sediment and stable bed morphology. Approach: In this study, flow and sediment characteristic measured at a laboratory flume and the presence or absence of clusters at each of these tests was recorded. A statistical analysis using logistic regression was performed to examine the correlation between the occurrence of clusters and various non-dimension combinations of measured variables. Results: It was found that the best parameters for predicting the clusters presence are gd

Discrimination of bed form scales using robust spline filters and wavelet transforms: Methods and application to synthetic signals and bed forms of the Río Paraná, Argentina

“…Past approaches to the quantification of bed form variability have used and applied spectral analysis [ Hino , ; Jain and Kennedy , , ; Annambhotla et al , ; Levey et al , ; Kheiashy et al , ], smoothing techniques such as a moving average [ Brinke et al , ; Julien et al , ; Wilbers and Brinke , ; Hoekstra et al , ; Frings and Kleinhans , ; van der Mark et al , ], signal roughness techniques [ Singh et al , ], fractals [ Wildhaber et al , ], and logistic regression [ Karbasi et al , ]. However, past research concerning the analysis of time series exhibiting multiscale time variability (similar to the multiscale spatial variability of bed form features) using moving average techniques, as well as Fourier series analysis, has generally shown that these techniques are insufficient as a tool to extract the long‐term variation from signals that contain a long‐term trend with a superimposed fine oscillation (i.e., the short term variation) [ Takezawa , ].…”