An experimental study of mounds formed by dumping coarse sediment in channel flow

Abstract

The development of large sediment mounds formed by continuous release of coarse materials in flowing water is reported. Growths of mound height, longitudinal profile and areal extent were examined for three flow conditions. Longitudinal profiles of depositions during the development phase of the mounds were approximately similar, and they can be expressed by an exponential function if scaled with the maximum height and a width parameter. From observations, it appeared that the mound peak shifted gradually towards upstream and followed the outer part of the sediment plume. The heap growth can be expressed as a function of buoyancy flux due to sediment disposal, flow momentum and densimetric particle Froude number. The deposition height increased with normalized time until reaching close to the water surface. The width and area developed faster with normalized time than the height. The deposition area with coarse sediment was characterized by a downstream tail and fin-like extensions on the sides which differed from observations in previous experiments with fine sand.

Keywords:

• Densimetric particle Froude number
• open channel flow
• sediment deposition
• sediment plume
• turbulent flow
• underwater mound

Acknowledgements

The authors are thankful to J. Gagné and J. Penrose for having done the tests and to S. Lovell for having built the test arrangement in the T. Blench Hydraulics Lab at the University of Alberta.

Additional information

Notes on contributors

Faruk Bhuiyan

IAHR Member

Nallamuthu Rajaratnam

IAHR Member