Large values of hydraulic roughness in subglacial conduits during conduit enlargement : implications for modeling conduit evolution

Auteur(s) et Affiliation(s)

GULLEY, J.D.

Michigan Technological Univ., Dept. of Geological and Mining Engineering and Sciences, Houghton, Etats-Unis

SPELLMAN, P.D.

Michigan Technological Univ., Dept. of Civil and Environmental Engineering, HOUGHTON, Etats-Unis

COVINGTON, M.D.

Dept. of Geosciences, Univ. of Arkansas, Etats-Unis

MARTIN, J.B.

Dept. of Geological Sciences, Univ. of Florida, Gainesville, Etats-Unis

BENN, D.I.

Univ. Centre in Svalbard (UNIS), Dept. of Arctic Geology, Norvege

CATANIA, G.

Inst. for Geophysics, Univ. of Texas, Etats-Unis

Description :
In this paper, the AA. calculated values for 2 roughness parameters, the Darcy–Weisbach friction factor (f) and the Manning roughness coefficient (n), using dye tracing data from a mapped subglacial conduit at Rieperbreen, Svalbard. Values of f and n calculated from dye traces were compared with values of f and n calculated from commonly used relationships between surface roughness heights and conduit hydraulic diameters. Equations that calculate roughness parameters from surface roughness heights underpredicted values of f by as much as a factor of 326 and values of n by a factor of 17 relative to values obtained from the dye tracing study. The AA. argue these large underpredictions occur because relative roughness in subglacial conduits during the early stages of conduit enlargement exceeds the 5% range of relative roughness that can be used to directly relate values of f and n to flow depth and surface roughness heights. Simple conduit hydrological models presented here show how parameterization of roughness impacts models of conduit discharge and enlargement rate.

Type de document :
Article de périodique

Source :
Earth surface processes and landforms, issn : 0197-9337, 2014, vol. 39, n°. 3, p. 296-310, nombre de pages : 15, Références bibliographiques : 1 p.

Date :
2014

Editeur :
Pays édition : Royaume-Uni, Chichester, Wiley

Langue :
Anglais