Journal
JOURNAL OF GLACIOLOGY
Volume 63, Issue 239, Pages 423-435Publisher
CAMBRIDGE UNIV PRESS
DOI: 10.1017/jog.2016.134
Keywords
glacier hydrology; roughness; subglacial conduits
Funding
- National Science Foundation (NSF) [1503928]
- Norwegian Arctic Research Council and Svalbard Science Forum, RiS [6106]
- National Aeronautics and Space Administration (NASA) Headquarters under the NASA Earth and Space Science Fellowship Program [NNX10AN83H]
- University of California, Santa Cruz
- Woods Hole Oceanographic Institution Ocean and Climate Change Institute post-graduate fellowship
- NSF EAR Postdoctoral Fellowship [0946767]
- NASA [NNX11AH61G]
- NASA [144824, NNX11AH61G] Funding Source: Federal RePORTER
- Division Of Earth Sciences
- Directorate For Geosciences [0946767] Funding Source: National Science Foundation
- Office of Polar Programs (OPP)
- Directorate For Geosciences [1503928, 1629893] Funding Source: National Science Foundation
Ask authors/readers for more resources
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 m(2), 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.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available