Spatial, seasonal and interannual variability of supraglacial ponds in the Langtang Valley of Nepal, 1999–2013

• Published in: Journal of glaciology Vol. 63; no. 237; pp. 88 - 105
• Main Authors: MILES, EVAN S., WILLIS, IAN C., ARNOLD, NEIL S., STEINER, JAKOB, PELLICCIOTTI, FRANCESCA
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01-02-2017
• Subjects: Annual variations; Atmospheric correction; Climate change; Debris; debris-covered glaciers; Detritus; Flow velocity; Geography; Glacial drift; glacier hydrology; Glaciers; High Mountain Asia; Hydrology; Ice; Ice cover; Interannual variability; Lakes; Landsat; Landsat satellites; Monsoon onset; Monsoons; Ponds; Precipitation; Remote sensing; Seasonal variability; Seasonal variations; Seasonality; Snowmelt; Spatial distribution; Studies; supraglacial ponds; Temporal distribution; Valleys; Variability; Wind; Mount Everest; United Kingdom > UK; China; Nepal; glacier hydrology; High Mountain Asia; debris-covered glaciers; remote sensing; supraglacial ponds
• ISSN: 0022-1430; 1727-5652
• DOI: 10.1017/jog.2016.120

Supraglacial ponds play a key role in absorbing atmospheric energy and directing it to the ice of debris-covered glaciers, but the spatial and temporal distribution of these features is not well documented. We analyse 172 Landsat TM/ETM+ scenes for the period 1999–2013 to identify thawed supraglacial ponds for the debris-covered tongues of five glaciers in the Langtang Valley of Nepal. We apply an advanced atmospheric correction routine (Landcor/6S) and use band ratio and image morphological techniques to identify ponds and validate our results with 2.5 m Cartosat-1 observations. We then characterize the spatial, seasonal and interannual patterns of ponds. We find high variability in pond incidence between glaciers (May–October means of 0.08–1.69% of debris area), with ponds most frequent in zones of low surface gradient and velocity. The ponds show pronounced seasonality, appearing in the pre-monsoon as snow melts, peaking at the monsoon onset at 2% of debris-covered area, then declining in the post-monsoon as ponds drain or freeze. Ponds are highly recurrent and persistent, with 40.5% of pond locations occurring for multiple years. Rather than a trend in pond cover over the study period, we find high interannual variability for each glacier after controlling for seasonality.