T94 Management and Restoration of Fluvial Systems: Rehabilitating or Accommodating Altered Hydrologic and Sediment Regimes

Monday, 26 September 2016
8:00 AM - 12:00 PM
Room 405

NUMERICAL SIMULATIONS ON THE EFFECT OF VARIATIONS IN CHANNEL WIDTH ON THE MORPHODYNAMICS OF GRAVEL-BED RIVERS

Paper number: T94-13
Program: Technical Sessions
Time: 11:00 AM – 11:15 AM

Authors

Abstract

River channels are often characterized by downstream variations in channel width. The effect of width variations on bed topography and sorting patterns, however, remains poorly understood, especially under conditions of changing sediment supply. In this study we use two-dimensional morphodynamic modeling to explore how channel width variations and changes in sediment supply influence channel morphology. Using Delft3D we systematically explore how the amplitude and wavelength of sinusoidal width variations affect the shape and location of bars, and sorting patterns between wide and narrow sections in a coarse-grained channel. We perform simulations with constant sediment supply, no sediment supply, and a sediment pulse with no background sediment feed. Preliminary results indicate that width variations force riffle-pool topography with riffles co-located with greater channel widths and pools located at narrow sections. The amplitude of the width variations is the dominant factor controlling riffle-pool relief and also influence whether central or side bars develop in riffle sections. We hypothesize that greater amplitude of width variations increases pulse dispersion. These ongoing numerical simulations will help guide forthcoming flume experiments and can potentially be used to guide stream restoration and river management objectives under conditions of varying sediment regimes.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-284366

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