Publication Abstracts

Mankoff et al. 2017

Mankoff, K.D., J.D. Gulley, S.M. Tulaczyk, M.D. Covington, X. Liu, Y. Chen, D.I. Benn, and P.S. Głowacki, 2017: Roughness of a subglacial conduit under Hansbreen, Svalbard. J. Glaciol., 63, no. 239, 423-435, doi:10.1017/jog.2016.134.

Hydraulic roughness exerts an important but poorly understood control on water pressure in subglacial conduits. Where relative roughness values are <5%, hydraulic roughness can be related to relative roughness using empirically-derived equations such as the Colebrook-White equation. General relationships between hydraulic roughness and relative roughness do not exist for relative roughness >5%. Here we report the first quantitative assessment of roughness heights and hydraulic diameters in a subglacial conduit. We measured roughness heights in a 125 m long section of a subglacial conduit using structure-from-motion to produce a digital surface model, and hand-measurements of the b-axis of rocks. We found roughness heights from 0.07 to 0.22 m and cross-sectional areas of 1-2 m2, resulting in relative roughness of 3-12% and >5% for most locations. A simple geometric model of varying conduit diameter shows that when the conduit is small relative roughness is >30% and has large variability. Our results suggest that parameterizations of conduit hydraulic roughness in subglacial hydrological models will remain challenging until hydraulic diameters exceed roughness heights by a factor of 20, or the conduit radius is >1 m for the roughness elements observed here.

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BibTeX Citation

  author={Mankoff, K. D. and Gulley, J. D. and Tulaczyk, S. M. and Covington, M. D. and Liu, X. and Chen, Y. and Benn, D. I. and Głowacki, P. S.},
  title={Roughness of a subglacial conduit under Hansbreen, Svalbard},
  journal={J. Glaciol.},
  publisher={Cambridge University Press},

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RIS Citation

ID  - ma00710o
AU  - Mankoff, K. D.
AU  - Gulley, J. D.
AU  - Tulaczyk, S. M.
AU  - Covington, M. D.
AU  - Liu, X.
AU  - Chen, Y.
AU  - Benn, D. I.
AU  - Głowacki, P. S.
PY  - 2017
TI  - Roughness of a subglacial conduit under Hansbreen, Svalbard
JA  - J. Glaciol.
VL  - 63
IS  - 239
SP  - 423
EP  - 435
DO  - 10.1017/jog.2016.134
PB  - Cambridge University Press
ER  -

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