ID:
publications-2655
Type:
Peer reviewed articles
Year:
2016
Authors:
Pascal Buri, Evan S. Miles, Jakob F. Steiner, Walter W. Immerzeel, Patrick Wagnon, Francesca Pellicciotti
Title:
A physically based 3-D model of ice cliff evolution over debris-covered glaciers
Venue/Journal:
Journal of Geophysical Research: Earth Surface
DOI:
10.1002/2016JF004039
Research type:
Data Management & Analytics
Water System:
Natural Water Bodies
Technical Focus:
Abstract:
AbstractWe use highâresolution digital elevation models (DEMs) from unmanned aerial vehicle (UAV) surveys to document the evolution of four ice cliffs on the debrisâcovered tongue of Lirung Glacier, Nepal, over one ablation season. Observations show that out of four cliffs, three different patterns of evolution emerge: (i) reclining cliffs that flatten during the ablation season; (ii) stable cliffs that maintain a selfâsimilar geometry; and (iii) growing cliffs, expanding laterally. We use the insights from this unique data set to develop a 3âD model of cliff backwasting and evolution that is validated against observations and an independent data set of volume losses. The model includes ablation at the cliff surface driven by energy exchange with the atmosphere, reburial of cliff cells by surrounding debris, and the effect of adjacent ponds. The cliff geometry is updated monthly to account for the modifications induced by each of those processes. Model results indicate that a major factor affecting the survival of steep cliffs is the coupling with ponded water at its base, which prevents progressive flattening and possible disappearance of a cliff. The radial growth observed at one cliff is explained by higher receipts of longwave and shortwave radiation, calculated taking into account atmospheric fluxes, shading, and the emission of longwave radiation from debris surfaces. The model is a clear step forward compared to existing static approaches that calculate atmospheric melt over an invariant cliff geometry and can be used for longâterm simulations of cliff evolution and to test existing hypotheses about cliffs' survival.
Link with Projects:
676819
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