IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 34th Congress - Brisbane (2011) : THEME 5: Environmental Hydraulics and Hydrology : Comparison of 2d laser scanning with 3d magnetic resonance imaging (mri) scanning; analysis of grade...
Comparison of 2d laser scanning with 3d magnetic resonance imaging (mri) scanning; analysis of graded gravel bed porosity
Author : E. Vignaga, A.Ockelford, H.Haynes, W.M. Holmes and D., Bertram
Surface/subsurface interaction in gravel beds plays a fundamental role in sediment mobility, surface/groundwater exchange and quality of the hyporheic zone. Porosity is a key parameter for all of these processes which requires an understanding of the 3D structure of the river bed; yet, this is difficult to determine using conventional invasive measurement techniques. This paper therefore compares porosity statistics derived using the non-invasive technique of surface-based laser displacement scanning (resolution ~0.1mm) with those calculated from 3D volumetric data acquired from Magnetic Resonance Imaging (MRI) (resolution =0.3mm). Four flume experiments exposed two grain size distributions [uniform (σg = (D84/D16)0.5 ~1.0); bimodal (σg = 2.08)] to two sub-threshold flow durations of 60 and 960 minutes. The samples were scanned with the laser, extracted from the flume and 3D images were acquired using MRI. Results consider: (i) the validation of the experimental procedure (Digital Elevation Models, DEMs); (ii) the limitations of the 2D imaging technique; (iii) 3D porosity estimations of the boundary surface/subsurface for the different beds and water-working periods.
File Size : 617,311 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 34th Congress - Brisbane (2011)
Article : THEME 5: Environmental Hydraulics and Hydrology
Date Published : 01/07/2011
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