Pascal and several team members have just had published their paper, A physically based 3-D model of ice cliff evolution over debris-covered glaciers, in the Journal of Geophysical Research: Earth Surface. They used a new data set of high-resolution observations of cliff evolution over one ablation season to identify patterns of changes over four cliffs on the debris-covered tongue of Lirung Glacier (Nepalese Himalaya). The four cliffs have different shape, dominant orientation and slopes, and different degree and history of coupling to a supraglacial pond. The observations show that cliffs on the same glacier and at short distance from each other can both flatten and recline, remain self-similar, or expand radially. Based on the observations a model accounting for the three main processes controlling cliff evolution was developed: atmospheric melt, pond contact ablation enhancement for the cliff base, and reburial by surrounding debris. This modeling approach is able to simulate the cliff evolution over one melt season in a satisfying way in terms of horizontal and vertical extent as well as mean slope and aspect. Modelled volume losses could be validated and were in agreement with TIN-based observations (Brun et al. 2016, Journal of Glaciology).
Simulated cliff evolution based on the monthly updated outlines.
The model is able to capture the main cliff dynamics and geometric transformation. Importantly, the model application has clearly shown that for very high resolution studies, neglecting a dynamic update of the cliff geometry would lead to erroneous results in terms of backwasting patterns and volumes.
We collect most of the data we use in our research in the field, in recent years to a large degree in the Nepalese Himalayas. Field work can have effects on your health – it’s cold, oxygen levels are low, work is exhausting and you are always a bit nervous about whether the next sensor you read out will actually have any data stored. All we have is ourselves – there is no internet or phone connection in our field site, there are showers, however not all team members know how to use it. We realized that this exhaustion somehow articulates itself by lack of sleep and weird songs stuck in your head. For the sake of future research in high altitude psychology we decided to document this mess from our recent trip to Langtang in October.
All the songs listed suddenly surfaced – mostly while walking – as humming or whistling by some team member and then quickly spread through the group and sometimes remained for days in our heads or quickly disappeared again. Most of them made us laugh, many were a nuisance and for some reason very few were actually good music.
To give you an idea of the deteriorating path we took during nearly 6 weeks in the field I’ll start at the very end. While by all common standards we could be declared more or less sane at the start of our work, on the very last day of our trip Joe, an outstanding musician and singer who has played on stages in a number of countries and myself, trained in classical music at University and hence supposedly with a good taste by upbringing, sang and danced respectively to …
The closest we got to putting a ring somewhere was the ring memory of our sturdy Campbell Scientific CR1000. We were joined by a completely hammered Nepali soldier looking for cigarettes, alcohol and entertainment and our steadfast porters who must wonder again and again whether the work we produce is actually worth anything at all considering our behaviour after a day’s work.
When we were asked by our local porters to sing our field song at parties that were regularly thrown in the kitchen tent or lodge we stayed in, for some strange reason we would sing
regularly, strange because the only Italian on the team hated it and none of the rest speak any Italian.
To reach our stations at the very back of the valley we always have an easy half day hike along the main river of the catchment. This year we could witness wild boars along the sand banks and yak herds crossing the forceful stream which we could only cross on bridges made from flagpoles.
Crossing with station equipment
Self made bridge over Langtang river
Yaks crossing the same river
The rockfalls along the river as a result of the earthquake in 2015 are impressive.
Rockfall as a result of the earthquake
New Rock Slide over the river
Having reached our camp, we played cards the whole evening sipping some of Joe’s fine treat – Whiskey transported in a Nalgene bottle. Like every night our kitchen staff would come around after a while and fill up our bottles with hot water for the night. In the dark, nobody noticed the difference between the half full Nalgene and the other water bottles. The result was a lukewarm, diluted Whiskey. Quite a downer at that point.
Remembering Whiskey …
Although we do make quite silly mistakes at times especially when working very high when the exhaustion and oxygen loss really kicks in perceptibly we do seem to be able to find matching song texts for the occasion. “Plug out that cable!” …”Are you sure? Do you really want that? Really really …?”
And likely on the approach to reading out a precious datalogger in the remotest location (although I’m not sure where that song popped up)
Many of those “earworms” as we call them in German were such a nuisance and difficult to get rid of, that Joe with everyone roped up on the glacier above 5300 m suddenly called for a halt. “Can you please help me get rid of that song in my head?”
Group roped up on Yala Glacier
View from the high weather station above 5000 m
Aptly for those sometimes quite difficult ascents at this elevation there was
at one point. That surely came from my side since I also come up with other romantic hogwash like Bryan Adams. But it seems that song only comes to me below a certain 02 threshold, I fail to remember which one it was.
After 3 days in high camp – if you wonder, that’s what it looks like if you can’t sleep:
– words and sanity left us completely and for a few hours the “refrain” of
became a thing. Luckily didn’t last long.
which hit Joe’s patriotic side next to a Pluviometer in horrible weather.
What our team of porters produces in this environment on the culinary side is always impressive. So are the views during the day and at night.
Last sunrays on Gangchampo
Card playing still ongoing
Kitchen busy at night with Lirung peak in the back
Before we are served dinner in our high altitude restaurant, we do get a bowl of soup which prompts everyone to crawl out of the tent again, stopping the late afternoon nap or field report writing. For some unbeknown reason I always whistle
during soup time. I’m too young for the Archies and didn’t even know the song. But always a team, Joe helped out and quickly put a title to my annoying habit.
We arrived back in Kathmandu in a horrible Jeep on a congested road with a song on the MP3 on repeat that really never should have existed.
Mountainhydrology will be at AGU Fallmeeting 2016 the coming week with a whole bunch of exciting posters and talks. Drop by, say hi and ask us on advice on how to fall asleep when a 800kg Yak incessantly burps next to your tent.
Research team member Evan Miles, based at the University of Cambridge, has recently passed his PhD viva and will now be Dr Miles! His thesis, titled ‘Spatio-temporal variability and energy-balance implications of surface ponds on Himalayan debris-covered glaciers’ has combined remote sensing, field surveys, and numerical modelling to understand the role of supraglacial ponds.
Figure 1: Evan Miles and Anna Chesnokova installing thermistor strings and a pressure transducer in a supraglacial pond on Lirung Glacier, May 2014.
New OA paper studying spatio-temporal variability of supraglacial ponds
Evan and several other team members have just had an Open Access paper published in the Journal of Glaciology based on one aspect of Evan’s doctoral work, Spatial, seasonal and interannual variability of supraglacial ponds in the Langtang Valley of Nepal, 1999–2013. The study uses 15 years of Landsat data (172 scenes) to analyse the variability of supraglacial ponds on a set of five debris-covered glaciers. This is a major advance in several ways, as prior studies have used only a few scenes to assess ponded area for debris-covered glaciers. The use of such an extensive dataset allowed the authors to also assess the spatial patterns of ponding and interannual changes in pond cover in a more robust way than has been done previously.
Figure 2: Spatial distribution of supraglacial ponds as percent of May–October observations (n =68), also showing results for other lakes outside the debris-covered tongues (orange ellipses), 1999–2013.
One of the most important results is the seasonal variability of ponds, which controls the role they can play in a glacier’s mass balance. Expect more news on that topic soon!
Figure 3: Seasonal pattern of thawed pond cover as percent of observable debris-covered glacier area, with individual scenes coloured by year of observation (n =172) and dot tails highlighting the effect of a 34% overestimation of pond area. The solid black line is the monthly mean, with dashed lines showing the ± 1σ spread.
Evan Miles to start Post-Doc in Leeds
Finally, Evan has accepted a two-year research position at the University of Leeds to work with Dr Duncan Quincey, Dr Bryn Hubbard (Aberystwyth University), and Dr Ann Rowan (Sheffield University) as part of the NERC-funded EverDrill project. This is an exciting and ambitious effort to drill to the bed of Khumbu Glacier and install a sensor suite to understand englacial and subglacial processes, a first for the Himalaya, and a critical need identified by other MountainHydrology team members. More project info can be found here. Evan will continue to be peripherally involved in many MountainHydrology projects.
The Indus is one of the most meltwater-dependent rivers on Earth, and hosts a large, rapidly growing population and the world’s largest irrigation scheme. Understanding the hydrology of the upper Indus basin is challenging. The Hindu Kush, Karakoram and Himalayan mountain ranges are difficult to access, hampering field measurements of meteorological, glaciological and hydrological processes. These processes are therefore still poorly understood. To make it more complex, climate change projections for the Indus basin show a very large spread. In our recent (open access) paper published in PLoS ONE we present hydrological projections for the 21st century in the upper Indus basin, based on a cryospheric-hydrological model forced with an ensemble of downscaled GCM outputs.
The Hunza river in front of the Passu cones (upper Indus basin).
Three methodological advances are introduced:
A new precipitation dataset that corrects for the underestimation of high-altitude precipitation is used.
The model is calibrated using data on river runoff, snow cover and geodetic glacier mass balance.
An advanced statistical downscaling technique is used that accounts for changes in precipitation extremes.
Our projections indicate decreases in glacier melt contribution in favor of snow melt and rainfall-runoff contribution to stream flow in the upper Indus basin, at the end of the 21st century.
The focus of the analysis in our study is not only on changes in sources of runoff and water availability but also on changes in seasonality and hydrological extremes, which are still large unknowns in the upper Indus basin. We conclude that the upper Indus basin faces a very uncertain future in terms of water availability towards the end of the 21st century. Despite the large uncertainties in future climate and water availability, basin-wide patterns and trends of intra-annual shifts in water availability are consistent across climate change scenarios. For the near future these trends mainly consist of minor increases in summer flows combined with increased flows during other seasons. For the far future the trends show decreases in summer flows combined with stronger increasing flows during the other seasons. Furthermore, increases in intensity and frequency of extreme discharges are found for most of the upper Indus basin and for most scenarios and models considered, implying increases in flooding events during the 21st century.
The study is presented at the AGU Fall meeting in San Francisco on Monday, 12 December 09:15 – 09:30, Moscone West – 3005
Analysis of future changes indicates increases in the frequency and magnitude of extreme flows for most of the UIB and most of the climate change scenarios.