Informatics Publishing Limited

Anil V. Kulkarni ¹, Yogesh Karyakarte ¹

Affiliations
1 Divecha Centre for Climate Change, Indian Institute of Science, Bangalore 560 012, IN

Abstract

In the Himalaya, large areas are covered by glaciers and seasonal snow. They are an important source of water for the Himalayan rivers. In this article, observed changes in glacial extent and mass balance have been discussed. Various studies suggest that most of the Himalayan glaciers are retreating though the rate of retreat varies from glacier to glacier, ranging from a few meters to almost 61 m/year, depending upon the terrain and meteorological parameters. In addition, mapping of almost 11,000 out of 40,000 sq. km of glaciated area, distributed in all major climatic zones of the Himalaya, suggests an almost 13% loss in area in the last 4-5 decades. The glacier mass balance observations and estimates made using methods like field, AAR, ELA and geodetic measurements, suggest a significant increase in mass wastage of Himalayan glaciers in the last 3-4 decades. In the last four decades loss in glacial ice has been estimated at 19 ± 7 m. This suggests loss of 443 ± 136 Gt of glacial mass out of a total 3600-4400 Gt of glacial stored water in the Indian Himalaya. This study has also shown that mean loss in glacier mass in the Indian Himalaya is accelerated from -9 ± 4 to -20 ± 4 Gt/year between the periods 1975-85 and 2000-2010. The estimate of glacial stored water in the Indian Himalaya is based on glacier inventory on a 1 : 250,000 scale and scaling methods; therefore, we assume uncertainties to be large.

Keywords

Glacial Stored Water, Glacier Retreat, Mass Balance, Snow.

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U. S. Maanya ¹, Anil V. Kulkarni ¹, Alok Tiwari ¹, Enakshi Dasgupta Bhar ¹, J. Srinivasan ¹

Affiliations
1 Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru 560 012, IN

Abstract

The Himalayan glaciers feed major Asian river systems sustaining the lives of more than 800 million people. Though the rates of retreat of individual glaciers are uncertain, on the whole the Himalayan glaciers have been losing mass at an increasing rate over the past few decades. With the changing climate, glaciers will continue to shrink and the rates of retreat may increase even further. This may lead to the formation of moraine dammed glacial lakes, which can cause outburst floods upon failure of the dam, catastrophic to human life and infrastructure downstream. Therefore, identification of potential lake sites and predicting the expansion of existing lakes are crucial for timely monitoring and mitigation of these hazards. In the present study, glacier surface velocity and slope are used to calculate ice thickness, by applying a basic parallel flow model, subsequently outlining the bed topography and locating potential lake sites in overdeepenings in the bedrock. Comparison of the modelled and measured ice thickness values on Chhota Shigri glacier suggests a model uncertainty of ±15%. The model is further applied to Samudra Tapu and Drang Drung glaciers using satellite data between the years 1999 and 2001, where eight potential lake sites were identified with mean depths varying between 33 ± 5 and 93 ± 14 m, of which three sites have a volume greater than 0.01 km³. The analysis predicts an over-deepening near the snout of Samudra Tapu, in close proximity to an existing moraine dammed lake. A portion of the predicted site has already evolved into a lake between the years 2000 and 2015, which upon further deglaciation could lead to an expansion of the existing lake by an area of 14 ± 2 ha. This observation further validates the model prediction of lake expansion. The present study demonstrates the utility of the model to predict maximum expansion of the existing lakes and possible formation of new lakes due to glacier retreat. Systematic application of this technique can provide information crucial to policy makers and planners dealing with the security of people living in the mountains.

Keywords

Bed Topography, Glacial Lakes, Ice Thickness, Remote Sensing.

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G. Vinay Kumar ¹, Anil V. Kulkarni ², Anil Kumar Gupta ³, Parmanand Sharma ¹

Affiliations
1 Cryosphere Science Division, ESSO-National Centre for Antarctic and Ocean Research, Goa 403 804, IN
2 Divecha Centre for Climate Change, CAOS, Indian Institute of Science, Bengaluru 560 012, IN
3 Department of Civil Engineering, Dr Ambedkar Institute of Technology, Visvesvaraya Technological University-RC, Bengaluru 560 056, IN

Abstract

Himalayan glaciers, which contribute to water security for almost 1.3 billion people in Asia, are now under threat due to climate change. Assessment of glacier mass balance changes is crucial to determine the implications of climate change, but in situ measurements are limited due to rugged terrain and harsh climate of the Himalaya. Remote sensing-based geodetic method is therefore important for studying the evolution of Himalayan glaciers at a large scale. In this study, the mass balance of glaciers located in Baspa basin (Western Himalaya) is estimated for a period of 11 years between 2000 and 2011, using geodetic method. Out of 89 glaciers in the basin, 42 glaciers (greater than 1 km²) covering an area of ~72% (215 km²) of the total glaciated area were selected for the study. A mean thinning of ~50 ± 11 m and mean accumulation of ~35 ± 11 m was observed during the study period, with the cumulative mass balance varying between -36.9 ± 1.98 and 6.47 ± 1.98 m.w.e. A mean annual mass loss of -1.09 ± 0.32 m.w.e.a^-1 was observed for the entire basin, suggesting that the glaciers in Baspa basin are losing mass at higher rate compared to the glaciers in central and eastern Himalayas. This study demonstrates the utility of geodetic method to estimate mass balance of glaciers at basin scale, which will be useful to assess future changes in glacial extent and stream run-off.

Keywords

Baspa Basin, Geodetic Method, Mass Balance, Western Himalaya.

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Anil V. Kulkarni , S. K. Satheesh

Abstract

Himalayan cryology

The Himalayan region, including Karakoram, possesses a large concentration of mountain glaciers. In addition, large area is also covered by seasonal snow during winter. Snow and glacier melt during summer provides water to the major Indian rivers. This makes these rivers perennial and they are considered as the lifeline of millions of people living along the banks. However, water availability can be affected due to changes in global and regional climate. This will have a profound impact on the livelihood of millions of people living in the region. Therefore, understanding changes in the cryosphere is important to assess future changes in water availability and its influence on the people. In this context, this special section in Current Science highlights the latest understanding of the Himalayan cryosphere.

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S. Pratibha ¹, Anil V. Kulkarni ¹

Affiliations
1 Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru 560 012, IN

Abstract

Supraglacial debris cover (SDC) influences surface energy balance and glacier dynamics. However, very few studies have been carried out to understand its distribution and evolution. Previous glacier investigations carried out in Baspa basin, Western Himalaya, focus on retreat and mass balance. Therefore, the present study monitored change in SDC area from 1997 to 2014 using Landsat data. SDC area change was estimated within a ‘minimum snow-free glacier area’ using normalized difference snow index (NDSI) and band ratio of near infrared and shortwave infrared. Threshold values for NDSI and band ratio map were derived manually. The study was carried out for a ‘minimum snow-free glacier area’ of 60.5 ± 2.4 sq. km out of 174 ± 7 sq. km of total glaciated area. SDC area of 31.5 ± 1.4, 33.2 ± 1.2, 34.6 ± 1.9 and 36.3 ± 0.7 sq. km for 1997, 2000, 2011 and 2014 respectively, was estimated. Analyses show a linear increase in SDC area from 1997 to 2014 by 2.8 ± 0.4%. Naradu, a benchmark glacier in the basin, show one of the highest increase in SDC area (5.6 ± 0.4%). The findings from the present study are in line with other published results that suggest retreat, glacier fragmentation and mass loss, which could be due to climate change. The present study can be extended further using the SDC map and the results, in glacier hydrology and mass balance modelling to predict future loss.

Keywords

Climate Change, Glaciers, Remote Sensing, Supraglacial Debris Cover, Western Himalaya.

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Anil V. Kulkarni ¹, S. Pratibha ¹, Nisha Mendiratta ², Akhilesh Gupta ²

Affiliations
1 Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru 560 012, IN
2 Climate Change Programme, Department of Science and Technology, New Delhi 110 016, IN

Abstract

The glaciers and seasonal snow melt feed numerous Indian rivers originating from the Himalaya and support millions of people. However, snow and glaciers are sensitive to climate change and the ongoing climate change will potentially affect water availability for millions of people living in North India. Therefore, comprehensive understanding of factors and processes affecting the Himalayan cryosphere is necessary.

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S. N. Remya ¹, Anil V. Kulkarni ¹, S. Pradeep ¹, D. G. Shrestha ²

Affiliations
1 Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru 560 012, IN
2 Sikkim State Council of Science and Technology, Department of Science and Technology and Climate Change, Development Area, Gangtok 737 101, IN

Abstract

Glacial lake outburst floods (GLOFs) are a hazard commonly reported in the glaciated terrain of the Himalaya. Glacier lakes can form if the glaciers retreat and the bottom topography overdeepens. We have adopted a technique to estimate the depth and volume of lakes using parameters such as glacier surface velocity, slope and laminar flow of ice. The technique has been automated using Python programming language. The method was applied in the Sikkim Himalaya to map potential lake sites and also to predict further expansion of existing glacier lakes. Studies were carried out for ten glaciers in the Tista river basin. The analysis suggests nine potential lake sites, including further expansion of four existing glacier lakes. To validate the results, the model lake boundary in 2001 was compared with the satellite-observed value of 2015 and field measurements made at the South Lhonak lake. The volume of the South Lhonak lake (in 2015) was estimated as 60 ± 10.8 million m³; with prolonged retreat of the glacier, the lake is likely to expand to a maximum volume of 90 ± 16.2 million m³. The above technique can provide new information to planners, leading to a more realistic approach in understanding the disaster potential of glacier lakes.

Keywords

Glacier Lakes, Depth and Volume Estimation, Remote Sensing, Disaster Potential, Over Deepening.

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Veena Prasad ¹, Anil V. Kulkarni ¹, S. Pradeep ¹, S. Pratibha ¹, Sayli A. Tawde ², Tejal Shirsat ¹, A. R. Arya ¹, Andrew Orr ³, Daniel Bannister ³

Affiliations
1 Divecha Centre for Climate Change, IN
2 Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bengaluru 560 012, IN
3 British Antarctic Survey, Cambridge, CB3 0ET, GB

Abstract

Glaciers in the Satluj river basin are likely to lose 53% and 81% of area by the end of the century, if climate change followed RCP 8.5 scenario of CNRMCM5 and GFDL-CM3 models respectively. The large variability in area loss can be due to difference in temperature and precipitation projections. Presently, Satluj basin has approximately 2000 glaciers, 1426 sq. km glacier area and 62.3 Gt glacier stored water. The current mean specific mass balance is –0.40 m.w.e. a^–1. This will change to –0.42 and – 1.1 m.w.e. a^–1 by 2090, if climate data of CNRM-CM5 and GFDL-CM3 are used respectively. We have used an extreme scenario of GFDL-CM3 model to assess the changes in the contribution of glacier melt to the Bhakra reservoir. Mass balance model suggests that glaciers are contributing 2 km³ a^–1 out of 14 km³ of water. This will increase to 2.2 km³ a^–1 by 2050, and then reduce to 1.5 km³ a^–1 by the end of the century. In addition, loss in glacier area by the end of century, will also increase the vulnerability of mountain communities, suggesting need for better adaptation and water management practices.

Keywords

Climate Change, Glacier, Glacier Melt Runoff, Himalaya, Mass Balance, Satluj Basin, Water Availability.

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