ID27: High Asia cryo-hydrology: processes and impacts across elevations
The river basins of High Mountain Asia (HMA) are characterized by extreme altitude ranges, integrating cryospheric processes in remote headwaters with ecosystems and society in lowland reaches. They are among the most important globally in terms of water supply, while also being among the most vulnerable to climate change. The region's remoteness and complexity present major challenges for both scientific understanding and water resource forecasting.
In this session we integrate diverse scientific and practical perspectives of HMA's mountain systems. Submissions could relate to observations (e.g. remote sensing, field measurements); numerical modelling (e.g. landscape elements or catchments); data integration (e.g. data-driven inference, data assimilation); and impact assessment (e.g. ecosystems, hydropower, geohazards). By drawing together these threads, we aim to promote interactions bridging scale and disciplinary boundaries to, for example, exchange on lessons learned, discuss multifaceted climate change impacts and consider prospects for operational water resource forecasting.
Abstract ID 478 | Date: 2022-09-13 10:00 – 10:10 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Silwal, Gunjan; Pradhan, Ananta Man Singh
Water Resources Research and Development Centre, Ministry of Energy, Water Resources and Irrigation, Government of Nepal, Nepal
Keywords: Conceptualization, Development Of Methodology, Data Analyses, Modelling And Result Analyses
Major perennial rivers of Nepal originate from the Himalayas and are substantially fed by snow and glacier melt particularly during the dry season of the year. However, global climate change has led to significant reduction in snowcover extent and accelerated glacier mass loss in the Himalayas in last past decades largely altering the timing, magnitude and distribution of seasonal runoff in snow-glacier-fed rivers. Thus the practical assessment and projection of the effect of snowcover extent and glacier changes on hydrological regime of the glacierized basins demand for reliable simulation of snow accumulation and melt, glacier mass balance and the evolution considering their interactions and feedbacks over time and space (Naz et al., 2014; Clarke et al., 2015; Huss and Hock, 2018; Rounce et al., 2020b) as well as uncertainty analysis associated with the climate models and scenarios, downscaling and bias correction approaches of climate data, input data for model calibration, model parameters and model structures (Panday et al., 2013; Nepal et al., 2017; Rounce et al., 2020b). This study aims to characterize and quantify the cascade of uncertainty in climate impact projections using CMIP6 ensemble on fresh water resources availability and distribution for effective climate change adaptation and mitigation strategies in the Himalayan catchments taking the Karnali River basin of Nepal as a case study . A well calibrated coupled glacier dynamics (Open global glacier model- OGGM) and a spatially distributed hydrologic model and a method for improving our understanding of effect of glacio-hydrologic model parameterization and regionalization alongside the climate models and climate change scenarios (RCPs) on the cascade of uncertainty is developed. The methods developed in this study can be implemented at both local and regional scale and the results can be used as a guide for water security and water resources management and to cope with compounding environmental challenges by water resources managers and stakeholders.
Abstract ID 271 | Date: 2022-09-13 10:10 – 10:20 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Santolaria-Otín, María (1,2); Ménégoz, Martin (3); Terray, Laurent (4); Lalande, Mickaël (3); García-Serrano, Javier (1,5)
1: Group of Meteorology, Universitat de Barcelona (UB), Barcelona, Spain
2: Basque Centre for Climate Change (BC3), 48940 Leioa, Spain
3: Univ. Grenoble Alpes, CNRS, IRD, G-INP, IGE, 38000 Grenoble, France
4: CECI, Université de Toulouse, CERFACS/CNRS, Toulouse, France
5: Barcelona Supercomputing Center (BSC), Barcelona, Spain
Keywords: Anthropogenic Forcings, Climate Variability, High Mountain Asia, Atmospheric Circulation Changes
Climate change in High Mountain Asia (HMA) is largely uncertain because the lack of local observations does not allow a proper estimation of long-term trends. The complex topography induces marked heterogeneities of the atmospheric variables in an area under the influence of both the Asian monsoons and the Western disturbances, two circulation patterns that show considerable variability from daily to decadal timescales. It is therefore challenging to simulate the climate variability in HMA. The ongoing retreat of glaciers observed in the Southern Himalayas suggests a significant warming signal, since there is no clear trend of precipitation in this area. The relative stability of the glaciers located on the western part of HMA observed over the last decades, with some glaciers showing even positive mass balance in the Karakoram region is more difficult to interpret. To explain this "Karakoram anomaly", several physical processes have been suggested, including cloud changes, summer cooling and winter snowfall increase. However, there is no consensus on the exact causes of this phenomenon and their relative contributions, including the role of anthropogenic influence. A general increase in precipitation is expected in this area, in relation to the warming associated with greenhouse gases that favour higher moisture rates in the atmosphere. This effect contrasts with the increase in aerosol concentrations observed in the Indian subcontinent that induces a local cooling and a weakening of the monsoon systems. In this study, a large set of observational and model datasets is used to investigate dynamical versus thermodynamic atmospheric changes in this area. Trends are decomposed to disentangle atmospheric circulation changes from thermodynamic signals, with their respective imprints in temperature, precipitation and snow cover. The method is first applied to observations to directly interpret the atmospheric trends over the last decades as well as their potential impacts on the cryosphere. Then, climate simulations including and excluding anthropogenic forcings, as well as single forcing experiments considering separately aerosols and greenhouse gases (DAMIP) are used to highlight their signature in the climate of HMA.
Abstract ID 515 | Date: 2022-09-13 10:20 – 10:30 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Pohl, Eric (1); Barandun, Martina (2)
1: Alpine Cryosphere and Geomorphology Group, Department of Geosciences, University of Fribourg, Fribourg, Switzerland
2: Institute of Earth Observation, EURAC research, Bolzano, Italy
Keywords: Mass Balance Variability, Climate, Uncertainty, Regression Analysis
A picture of strong heterogeneous mass balance variability over Central Asia was previously identified using a snowline observation-based mass balance modelling approach. The high temporal (annual) resolution of this approach provides the possibility to investigate the spatio-temporal patterns of mass balance variability in addition to the purely spatial heterogeneity previously reported for the region based on geodetic methods. The dataset allows investigating the relationship between mass balance and potential meteorological drivers over time. However, large uncertainties in meteorological datasets, due to lack of precise ground truthing, renders this investigation difficult. We present an in-depth analysis using multiple, frequently used reanalysis and satellite-based snow cover datasets, as well as topographic parameters in multiple linear regression analyses to identify spatial and temporal mass balance variability relationships with climatic and static drivers. Based on the chosen meteorological data, the derived relationships can vary significantly and prevent conclusive understanding. We extend this study by incorporating mass balance estimates from a recent geodetic study to highlight the range of possible conclusions that can be drawn, and, that great care should be taken when concluding driving factors of mass balance variability.
Abstract ID 293 | Date: 2022-09-13 10:30 – 10:40 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Stigter, Emmy (1); Steiner, Jakob F. (1,2); Koch, Inka (2,3); Saloranta, Tuomo (4); Kirkham, James D. (2,5); Immerzeel, Walter (1)
1: Department of Physical geography, Utrecht University, The Netherlands
2: International Centre for Integrated Mountain Development, Nepal
3: Department of Geosciences, University of Tübingen, Germany
4: Hydrology department, Norwegian Water Resources and Energy Directorate, Norway
5: Scott Polar Research Institute, University of Cambridge, United Kingdom
Keywords: Snow, Observations, Himalaya, Energy Balance
Snow dynamics play a crucial role in the hydrology of alpine catchments in the Himalaya. However, studies based on in-situ observations that elucidate the energy and mass balance of he snowpack at high altitude in this region are scarce. In this study, we use meteorological and snow observations at two high-altitude sites in the Nepalese Himalaya to quantify the mass and energy balance of the seasonal snowpack. Using a data driven experimental set-up we aim to understand the main meteorological drivers of snowmelt, illustrate the importance of accounting for the cold content dynamics of the snowpack, and gain insight into the role that snow meltwater refreezing plays in the energy and mass balance of the snowpack. Our results show an intricate relation between the sensitivity of melt and refreezing on the albedo, the importance of meltwater refreezing, and the amount of positive net energy used to overcome the cold content of the snowpack. The net energy available at both sites is primarily driven by the net shortwave radiation, and is therefore extremely sensitive to snow albedo measurements. We conclude that, based on observed snowpack temperatures, 21% of the net positive energy is used to overcome the cold content build up during the night. We also show that at least 32–34% of the snow meltwater refreezes again for both sites. Even when the cold content and refreezing are accounted for, excess energy is available beyond what is needed to melt the snowpack. We hypothesize that this excess energy may be explained by uncertainties in the measurement of shortwave radiation, an underestimation of refreezing due to a basal ice layer, a cold content increase due to fresh snowfall and the ground heat flux. Our study shows that in order to accurately simulate the mass balance of seasonal snowpacks in Himalayan catchments, simple temperature index models do not suffice and refreezing and the cold content needs to be accounted for.
Abstract ID 328 | Date: 2022-09-13 10:40 – 10:50 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Khadka, Arbindra (1,2,3); Wagnon, Patrick (1,2); Brun, Fanny (1); Shrestha, Dibas (3)
1: University of Grenoble Alpes, France
2: ICIMOD, Nepal
3: Tribhuvan University, Nepal
Keywords: Everest, Reanalysis Data, Glacier
We present a multi-site evaluation of meteorological variables in the Everest region (Nepal) using ERA5-Land and HARv2 reanalyses compared to in-situ observations, based on classical statistical metrics. Observation data have been collected since 2010 by seven meteorological stations located on or off glaciers between 4260 m a.s.l. and 6352 m a.s.l. in the upper Dudh Koshi basin. 2-m air temperature, relative humidity, wind speed, incoming shortwave, and longwave radiations, as well as precipitation, are considered successively. Overall, ERA5-Land reanalysis performs slightly better than HARv2 except for wind speed. Due to the complex topography, even the highest resolution reanalysis products fail to reproduce the observations, especially for variables that have a large spatial variability such as precipitation or wind speed. Air temperature is the variable that is best captured by reanalyses, as long as an appropriate lapse rate, spatiotemporally variable and preferentially assessed by local observations, is used to extrapolate it vertically. A cold bias is still observed but attenuated over clean-ice glaciers. On average, we observe a moderate humid bias, slightly more important for HARv2 than for ERA5-Land, resulting in a spectacular over-estimation of precipitation during the monsoon and in relative humidity a little too high the rest of the year. The agreement between reanalysed and observed shortwave and longwave incoming radiations depends on the elevation difference between the station site and the reanalysis grid cell. The seasonality of wind speed is only captured by HARv2. Before being used for glacier mass and energy balance studies, reanalysis data must be bias-corrected using in-situ meteorological records.
Abstract ID 378 | Date: 2022-09-13 10:50 – 11:00 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Martin, Léo (1); Westermann, Sebastian (2); Magni, Michele (1); Fanny, Brun (3); Fiddes, Joel (4); Lei, Yanbin (5); Kraaijenbrink, Philip (1); Mathys, Tamara (6); Immerzeel, Walter (1)
1: Utrecht University, The Netherlands
2: Oslo University, Norway
3: IRD-IGE, France
4: WSL Institute, Switzerland
5: Institute of Tibetan Plateau Research, China
6: University of Fribourg, Switzerland
Keywords: Thermo-Hydrological Modeling, Catchment Scale, Cryo-Hydrology, Lake Level, Tibet
Ground thermal regime of high mountain catchments impacts the distribution between infiltration and runoff, latent and sensible heat fluxes, frozen and liquid subsurface water and the presence (or absence) of permafrost. In the context of global warming, hydrological modifications associated to ground thermal changes are of critical importance for extensive headwater regions such as the Qinghai-Tibet Plateau (QTP) and the Himalayas, which are major water towers of the world. Many watersheds of the QTP have seen their hydrologic budget modified over the last decades as evidenced by strong lake level variations observed in endorheic basins. Yet, the role of ground thermal changes in these variations has not been assessed.
Lake Paiku (central Himalayas, southern TP) has exhibited important level decreases since the 70s and thus offers the possibility to test the potential role of ground thermal changes and permafrost thaw on these hydrologic changes. We present distributed ground thermo-hydric simulations covering the watershed over the last four decades to discuss their implications on the lake level changes. We use the Cryogrid model to simulate the surface energy balance, snow pack dynamics and the ground thermo-hydric regime while accounting for the phase changes and the soil water budget. Because the surface radiative, sensible and latent heat fluxes in alpine environments are strongly dependent on the physiography, the model is forced with distributed downscaled forcing data produced with the TOPOSCALE model to account for this spatial variability. Simulated surface conditions are evaluated against meteorological data acquired within the basin, ground surface temperature loggers and remotely sensed surface temperatures. The simulations show that, contrary to large scale estimates of permafrost occurrence probability, an significant part of the basin is underlaid by permafrost (>20%). We also show that over the 1980-2020 period, ground temperature warmed up by 1.5 to 2°C per centuries. The permafrost limit rose from 5100 to 5300 m asl (in 40 years). Unfrozen surface conditions increased by around 25 days per century and evaporation increasing by +22% over the period. To represent the impact of these changes on the lake level, we included them in a simple hydrological budget calculation including the contribution of glacier melt and lake evaporation. This approach shows that ground thermo-hydric changes in the catchment have contributed to the lake level changes. These first results highlight the potential of thermo-hydric simulation to better quantify hydrological changes to come in the QTP.
Abstract ID 268 | Date: 2022-09-13 11:00 – 11:10 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Rowan, Ann V. (1,2); Quincey, Duncan J. (3); Hubbard, Bryn (4); Miles, Evan (5); Miles, Katie (4); Kirkbride, Martin (6); Hornsey, Josephine (1)
1: University of Sheffield, United Kingdom
2: University of Bergen, Norway
3: University of Leeds, United Kingdom
4: Aberystwyth University, United Kingdom
5: WSL, Switzerland
6: University of Dundee, United Kingdom
Keywords: Khumbu Glacier, Hot-Water Drilling, Debris-Covered Glaciers, Holocene
Regional satellite observations of glacier mass change indicate that debris-covered glaciers are shrinking at similar rates to clean-ice glaciers across High Mountain Asia, and that the rate of glacier mass loss is accelerating. This greater-than-expected mass loss has been partly attributed to differential ablation processes that locally enhance mass loss within the debris-covered section of the glacier, for example at ice cliffs and supraglacial ponds, and to changes in ice flow as glaciers respond to climate change. For the last five years, we have measured the englacial properties of the high-elevation debris-covered Khumbu Glacier in the Everest region of Nepal and combined these data with observations of the geomorphological expression of longer-term glacier change through the Holocene and the Little Ice Age. Data collection has included observations of ice temperature from deep boreholes through the glacier, englacial debris distribution, supraglacial hydrology from dye tracing, sub-debris melt from measurements of supraglacial debris temperature, and the timing and rate of glacier mass change from terrestrial cosmogenic nuclide exposure-age dating of Holocene moraines built by Khumbu Glacier and the adjacent Lobuche Glacier. These data are used to constrain a numerical model of the evolution of Khumbu Glacier through the Late Holocene to the present day, with the aim of developing and testing models of the dynamic behaviour of high-elevation debris-covered glaciers and improving the parameterisation of their behaviour in projections of future regional and global glacier change.
Abstract ID 731 | Date: 2022-09-13 11:10 – 11:20 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Singh, Chetan (1); Mandal, Arindan (1); Soheb, Mohd (1,2); Sharma, Parmanand (3)
1: Jawaharlal Nehru University, India
2: Heidelberg University
3: National Centre for Polar and Ocean Research,India
Keywords: Snow, Surface Energy Balance, Latent Heat, Sublimation
The study presents point-scale wintertime surface energy balance (SEB) of the snow surface in the cold arid environment at 5114 m a.s.l. in the Lato catchment in the Ladakh region of India from October 2018 to March 2021. The study includes those days of winter months (October to March) when albedo was greater than 40% for computation of snow SEB to understand the processes and drivers of SEB and sublimation of snow. We also investigate the control of cloud cover on SEB components and sublimation. The bulk Aerodynamic method including stability corrections is employed to calculate turbulent heat fluxes. The relative contribution of turbulent heat fluxes and net radiation to SEB are 83% and 17%, respectively, indicating turbulent heat flux, particularly Latent heat (67%) governing the winter SEB of the snow surface. Cloud cover controls SEB on overcast days by reducing shortwave incoming radiation by up to 70% and consequently sublimation rate by 61%. The computed winter sublimation rate is 2.23 mm we d-1 which is relatively greater than that of western and central Himalayan glaciers/snow surface, located at similar altitude, highlighting dry air favoring higher sublimation in the cold arid regime of Ladakh. We also observe that mid-latitude western disturbances induced winter precipitation impede sublimation rate from 2.46 to 1.74 mm we d-1 through the influx of high moisture in the region.
Abstract ID 693 | Date: 2022-09-13 11:20 – 11:30 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Van Tricht, Lander; Huybrechts, Philippe
Vrije Universiteit Brussel, Belgium
Keywords: Glaciers, Modelling, Tien Shan, Climate Change, Kyrgyzstan
High Mountain Asia (HMA) contains the largest concentration of glaciers outside the polar regions. These glaciers play an essential role in terms of water supply for the surrounding densely populated lowland areas. During summer months, the contribution of glacier meltwater to fresh water supply for households, agriculture and industry can increase to more than 50%. The retreat of these glaciers consequently can have a major impact. However, few detailed modelling studies exist that examine in detail how individual ice bodies in the area are responding to climate change. Further, different climatic and topographic settings ensure a heterogenous impact on ice masses in the area. In this study, we focus on the Tien Shan mountain range in the northwest of HMA. During the Soviet era, various glaciological measurements were carried out in this region. After abandonment in the nineties, different measurement programs have reinitiated in the last decades. We use several recent measurements and reconstructions of the ice thickness, surface elevation, surface mass balance and ice temperature to study in detail six different ice masses in the Kyrgyz Tien Shan: 5 valley glaciers and 1 ice cap. The selected ice bodies are located in different sub-regions of the Tien Shan with different climatic settings, and they are all characterised by detailed recent glaciological measurements. A 3-dimensional higher-order model is calibrated and applied to simulate the evolution of the ice masses since the Little Ice Age and to make a prognosis of the future evolution up to 2100 under different climate scenarios.
Abstract ID 334 | Date: 2022-09-13 11:30 – 11:40 | Type: Oral Presentation | Place: THEOLOGIE – SRVI |
Saloranta, Tuomo M. (1); Hegdahl, Trine J. (1); Steiner, Jakob F. (2); Melvold, Kjetil (1)
1: Norwegian Water Resources and Energy Directorate (NVE), Norway
2: International Centre for Integrated Mountain Development (ICIMOD), Nepal
Keywords: Water Resources, Snow, Himalaya, Nepal
The seasonal snow cover in high-mountain Asia is an important source of melt water for domestic use, irrigation and hydropower production, especially in the long dryer season after the 3-4 month long monsoon rain period has passed. At the same time, snow cover can also be a cause of disasters, such as avalanches and slush flows. Thus, there is a great demand for up-to-date information on the snow conditions and water discharge in the rivers in the remote Himalayan environment.
In our study we combine a snow mapping model (seNorge) and a hydrological model for two pilot study catchments remotely located in the Nepal Himalayas in the Langtang and Mustang regions. We set-up and couple snow mapping and streamflow forecasting systems, which together can give estimates of the current status as well as medium- and long-range prognosis on expected snow conditions and water discharge in these two catchments. This type of information may benefit the local water managers. It may also provide useful information on snow conditions and for producing avalanche danger bulletins for local citizens, tourist operators and tourists.
Our model setup utilizes and compares meteorological forcing data from (1) robust and almost maintenance-free in-situ weather and snow measurement stations located between 4000-5000 m elevation with real time satellite data transmission, as well as (2) meteorological forecasts from a global weather forecast model (ECMWF IFS). The single-layer snow model features an extended degree-day melt algorithm where estimation of snow melt model parameters is based on local meteorological and snow observations. Melt water refreezing, which may be a significant factor in hampering melt water runoff from the snow pack, is also simulated taking into account the depth of the refreezing front and insulation effect of the overlying snowpack.
FinaIly, a web- and mobile phone-based solution is planned to enhance communication between the scientists and the local citizens. This application (regObs) aims to enable easy registration of local snow, weather, geohazard, etc. observations (data sharing and exchange by crowd-sourcing).
Abstract ID 207 | Date: 2022-09-13 15:21 – 15:31 | Type: Oral Presentation | Place: SOWI – Garden |
Mitkari, Kavita (1); Sofat, Sanjeev (1); Arora, Manoj K. (2); Tiwari, Reet Kamal (3)
1: Punjab Engineering College (Deemed to be University), India
2: BML Munjal University, Gurugram, Haryana, India
3: Indian Institute of Technology Ropar, Rupnagar, Punjab, India
Keywords: Glacier Features, Debris-Cover, High Spatial Resolution, Obia
Accurate and detailed mapping of glacier features can be efficiently done from high spatial resolution remote sensing images using object-based image analysis (OBIA). OBIA that works on a group of pixels (i.e., objects) offers possibilities for situations where spectral properties are not unique, but where shape and/or neighbourhood relations are distinct. It also provides a means to work collectively on data from varied sources and at different measurement scales and units (using multiscale segmentation) and weigh them based on their importance. However, since the debris covered glacier features exhibit irregular shapes due to complex landforms, the challenges that OBIA can pose are to determine the correct spatial scale, define meaningful context and pattern relations, and classify based on spectral, spatial, contextual, and hierarchical criteria.
In this paper, we have developed an OBIA paradigm which establishes contextual and hierarchical relation among objects for sequential extraction of debris covered glacier features like snow/ice, ice-mixed debris (IMD), supraglacial debris (SGD), periglacial debris (PGD), valley rock, debris cones, supraglacial lakes/ponds including mountain shadows by integrating multispectral, thermal, and slope information into one workflow. We have used remote sensing imagery of Linear Imaging Self-Scanning System (LISS)-IV satellite sensor procured from National Remote Sensing Centre, Hyderabad, India. Ancillary information such as slope derived from ASTER Global DEM v2 and brightness temperature derived from Landsat Thematic Mapper thermal band have also been used to deal with the spectral resemblances between glacier surface (snow/ice + IMD + SGD) and non-glacier surface (PGD + valley rock). As a case study, we have considered the debris covered Gangotri Glacier which is one of the largest glaciers in the Himalayas. Its ablation zone is full of supraglacial lakes/ponds. The OBIA paradigm has been developed in the most widely known OBIA software i.e., eCognition. The novel contributions of this study are precise classification of shadow regions without manual corrections and discrimination of glacier surface features namely, snow/ice, SGD, and SGD without using short-wave infrared band. This study is also first of its kind to map small yet important geomorphological feature of a debris covered glacier i.e., debris cones which are conical-shaped depositions of thick debris sufficient to inhibit the melting of the ice beneath it. The large-scale thematic glacier map has been produced with a high overall accuracy of ≈90%.
Abstract ID 722 | Date: 2022-09-13 15:15 – 15:17 | Type: Poster Presentation | Place: SOWI – Garden |
Brun, Fanny (1); Lambrecht, Astrid (2); Mayer, Christoph (2); Berthier, Etienne (3); Dehecq, Amaury (1); Rezaei, Janali (1); Völksen, Christof (2); Deschamps-Berger, César (4)
1: Univ. Grenoble Alpes, CNRS, IRD, IGE, Grenoble, France
2: Bavarian Academy of Sciences and Humanities, Munich, Germany
3: LEGOS, Toulouse, France
4: Instituto Pirenaico de Ecología, CSIC. Avda Montañana 1005. Zaragoza, Spain
Keywords: Glacier, Pamir, Remote Sensing
Fedchenko Glacier, located in the central Pamir in Tajikistan, is the longest glacier in Asia. Due to its prominent location and its large size, it attracted scientific interest over the course of the twentieth and twenty first centuries, providing thus a rare legacy of historical data in Central Asia. In this study, we investigate a series of topographic data from 1928 to 2019. We use topographic maps collected during historical expeditions in 1928 and 1958. We take advantage of modern satellite data, such as KH-9 spy satellite (1980), SPOT5 (2010) and Pléiades (2017 and 2019). We also rely on ICESat campaign of 2003 and numerous GNSS surveys conducted in 2009, 2015, 2016 and 2019, which ensures a proper co-registration of the satellite data.
We calculate a mean rate of elevation change of -0.40 m/yr for 1928-2019, with a maximum thinning at the lowermost locations (approaching -0.90 m/yr). Despite this long-term thinning trend, we observe large contrasts between the sub-periods. The thinning rate of the tongue doubled for two sub-periods (1958-1980 and 2010-2017) compared to the long-term average. The ERA5 reanalysis (1950-2020) and the Fedchenko meteorological station records (1936-1991) reveal a dry anomaly in 1958-1980, followed by a wet anomaly in 1980-2010, which might have compensated for the temperature increase and thus mitigated mass losses. This wet anomaly could be an important feature of the "Pamir-Karakoram" anomaly, characterized by limited glacier mass losses in this region during the early twenty-first century. Our work contributes to better constrain the decadal glacier thickness changes, with unprecedented temporal resolution. This opens the way for more sophisticated approaches that link the glacier response to climate variability over decades.
Abstract ID 519 | Date: 2022-09-13 15:17 – 15:19 | Type: Poster Presentation | Place: SOWI – Garden |
Mandal, Sandip Tanu; Sharma, Milap Chand
Jawaharlal Nehru University, India
Keywords: High Mountain Asia, Glacier Changes, Corona Imagery, Glacial Lakes, Debris-Covered Glaciers
Glaciers in the High mountain regions and ice caps outside the polar regions cover ~680000 km2, about 4.2 % of the total ice-covered Earth surface. Mountain glaciers are key indicators of climate change on both a global and temporal scale. There has been substantial glacier mass loss since the Little Ice Age, and especially in the last century, glacier recession has been remarkable. The Hindukush Himalaya and Karakoram (H-K-H) regions are some of the most glaciated regions outside the polar regions. Recent estimates of glacier area for the H-K-H region, based on mapping using satellite imageries, is ~40800 km2 (Himalaya, ~22800 km2; Karakoram, ~18000 km2). Snow and glacial meltwaters have immense importance in the continuous fresh water supply for drinking, irrigation, hydroelectricity generation. Any loss of mass in the glaciers will directly impact the socio-economic conditions of the millions downstream. Snow and Glacier-melt runoff from the Himalayas maintain the perennial flow of the Indus, the Ganga, and the Brahmaputra river systems.
Glaciers are threatened by climate change. On a global scale, glacier changes have an immense impact on processes of global importance such as sea-level rise, Hydrology of glacier melt-water fed rivers, freshwater balance of oceans. Scientific studies indicate that glaciers in the 'Third Pole' are retreating at rates comparable to those in other parts of the world and confirm that the rate has accelerated in the past century. But, the pattern of the recession is not uniform throughout the region. Many factors, such as local topography, local climate influence the changes in these glaciers. This study tries to present a detailed account of glaciers in the Milang watershed in the Lahaul region of the Western Himalaya. It tries to assess changes in the area and length of the glaciers using remote sensing data and field observations. In the watershed, glaciers have lost around 5.35 ±0.45 % area between 1971 and 2021 and have seen formation and expansion of two pro-glacial lakes. The glaciers have retreated at an average rate of 4.38 ±0.43 m year-1 during the same period. However, the retreat rate varies highly among the glaciers. This study also investigates the influence of different topographic parameters, debris cover etc. on variable glacier changes.
Abstract ID 947 | Date: 2022-09-13 15:19 – 15:21 | Type: Poster Presentation | Place: SOWI – Garden |
Ghosh, Tanisha; Guha, Supratim; Tiwari, Reet Kamal
Geomatics Engineering Laboratory, Department of Civil Engineering, Indian Institute of Technology Ropar, Punjab, India-140001
Keywords: Glacier Response, Ladakh, Friedman Test, Statistical Tests, Area Changes
The assessment of glacial area changes has become very crucial due to variations in glacier retreat or surge, as it helps in understanding the future availability of water. Pertaining to the research region, the spatio-temporal analysis of these changes is rather apparent in Himalayan glaciers, but little is known about them. The current study examines the temporal rate of glacier area change estimations across the entire Indian Union Territory of Ladakh, revealing varied responses of 56 glaciers over the period 1992 to 2020. In order to figure out the changes in the glaciers, we used satellite images from the Landsat series and Google Earth. We estimated the differences in rate of area changes for individual glaciers for five different years, namely, 1992, 2004, 2009, 2014 and 2020. In four time frames, 1992 to 2004, 2004 to 2009, 2009 to 2014, and 2014 to 2020. To do so, we have first manually digitized each glacier for the specified years. As the time intervals were not uniform, we have converted the area change to annual average area change. Then to understand the temporal area change, a non-parametric analysis named the Friedman Test is used. This tells us about the results being equal or not. If the results are unequal, a non-parametric post hoc test (Dunn's test) is automatically run. Ultimately, we found out that in the first two time frames, the rates of area changes are -0.01477 to 0.05011 km2/year and -0.00897 to 0.05812 km2/year, being approximately equal. After that, in the time span of 2009 to 2014, an increasing trend is noticed in the rate of area changes to -0.03467 to 0.15912 km2/year and finally, a drastic increase is seen in the time span of 2014 to 2020 with a range of 0.20921 to 1.69050 km2/year. We observed that the area is varying diversely in the Ladakh region. This tells us how important it is to analyze the temporal area changes in the Ladakh region. We propose that glaciers be monitored on a regular and systematic basis in order to reduce glacial hazards in the Himalayas.
Abstract ID 946 | Date: 2022-09-13 15:31 – 15:33 | Type: Poster Presentation | Place: SOWI – Garden |
Guha, Supratim; Tiwari, Reet Kamal
IIT Ropar, India
Keywords: Glacier Mass Balance, Central Himalaya, Debris Cover, Morphological Parameter
Understanding current and future glacier mass change are crucial to avoiding water-scarcity-induced socio-political instability. The glacier response which can be calculated by measuring area changes, length changes, thickness changes, or mass balance is not equal at the catchment scale. It can be explained by a complex interplay of many morphological factors, which is very important to understanding the future of an individual glacier. Therefore, the satellite-based geodetic mass balance has been calculated in the Central Himalayan region to know the current status of the glaciers in this region and understand which morphological parameters are responsible for their heterogeneous mass balance. The "best subset method" has been used to identify the confining parameters from the list of probable parameters reported in the previous studies. After that, multiple linear regression was introduced to understand the relation between the selected parameters and the mass balance. The result of the mass balance shows that the average mass balance is -0.799±0.209 m.w.e.y-1 in the studied sample glaciers. Also, the 95% confidence interval shows that the range of mass loss lies between -0.507 to -1.08 m.w.e.y-1 in the entire Garhwal Himalayan region. The result also indicates that the larger mass balance ranges are due to variations in the mean slope and percentage of debris cover in the glaciers. In detail, the debris cover has a positive coefficient, meaning that the mass balance is negative, however, this negative effect decreases with an increase in the debris cover and vice versa. On the other hand, mass balance is inversely proportional to the mean slope of the glacier. That means mass balance is more negative when the slope is steep, and less negative or positive mass balance can be seen over gentler slopes. We also observed an approximate mass gain of 0.36 m.w.e.y-1 with the rise of 10% debris cover for a given slope. Additionally, an interesting phenomena was noticed that as the steepness of the slope surges by 10%, the mass loses by 0.86 m.w.e.y-1 for debris cover glacier.