Glacier Mapping in India since the 19th Century

Rakesh Bhambri, Tobias Bolch, Ravinder Kumar Chaujar

Glacier maps are significant resources to obtain information about glacier variability, mass balance estimation, calculate changes in ice volume, hydro power planning and estimate the position of the equilibrium line. They also provide details about the landforms made by the glaciers. This paper presents the progress of glacier mapping in Indian Himalaya since the mid-nineteenth century, and the contributions of remarkable field based Himalayan surveys and expeditions for mapping glacial features. This appraisal provides a comprehensive overview of the constraints and challenges relating to mapping of cleanice and debris-covered glaciers in the Indian Himalaya. This requires a need for further improvement, and possible solutions are suggested. In addition, opportunities of remote sensing and GIS are highlighted, and short review of the recent knowledge on glacier changes in the Indian Himalaya is presented.

Introduction

The glacier maps represent the spatial morphology of glacier terrain features and its surroundings slopes, mountain ridges and peaks on maps in particular times. Most of these maps are detailed, large scale, and hence provide valuable information for researchers, mountaineers and climbers. Moreover, due to the recent debate on climate change and its impact on Himalayan glaciers, these maps are of high value for the glaciological research. They are valuable assets for generating an inventory of glaciers and to study glacier area changes, and changes in ice volume in comparison with other more recent data. More detailed analysis allow to estimate the mass balances of glaciers, e.g. for hydrological purpose such as irrigation and hydro power planning. However, all these uses are fundamentally governed by the accuracy and authenticity of the original map resource.

The Himalaya comprise one of the largest collections of glaciers outside the polar regions, with a glacier coverage of ~33,000 km2 with a total number of about 10,000 glaciers in the Indian Himalaya. The Himalayan glaciers within the Indian subcontinent are broadly divided into the three river basins, namely the Indus, Ganga and Brahmaputra. The Indus basin has the largest number of glaciers (~8000), whereas the Ganga basin including Brahmaputra contain about 1600 glaciers. (Raina and Srivastava, 2008).

Existing studies of Himalayan glaciers indicate that many Himalayan glaciers are receding at different rates during the last decades (Bhambri and Bolch, 2009). Climate change in mountain regions has been one of the significant factors in understanding glacier variability. One recent published study reveals that seasonal mean, maximum and minimum temperature over the Western Himalaya has increased by ~2.0°C, ~2.8°C and ~1.0°C respectively between 1984/85 to 2007/08 (Shekhar et. al. 2010). The water discharge from the Himalayan glaciers contributes to a certain amount to the overall river runoff. The water is utilised by a large population of northern India for their domestic needs and irrigation for agricultural crops which play a vital role in economical and social life of northern India people.

Thus, regular monitoring of a large number of Himalayan glaciers is essential not only for scientific purposes but especially to improve the knowledge about the water resources for the benefit of the society. Although field investigations are highly recommended, only a limited number of glaciers are investigated as they demand a great deal of time, capital and involve high risks in remote mountain areas. Geoinformatics techniques provide abundant potential for mapping and monitoring the large coverage of glaciers at regular interval. Especially historic glacier maps allow extending the investigation back in time. The aim of this paper is to present a general overview of glacier mapping in India since 19th century, to highlight the opportunities of geoinformation, and to provide a short overview of the recent knowledge on glacier changes in the Indian Himalaya.

Topographic glacier mapping since the mid-nineteenth century

The Survey of India (SOI) is the primary agency of India involved in surveying the Himalayan mountain region since its establishment in 1767. Several field based surveys, especially the plane-table surveys of the Mustakh range, various expeditions of Longstaff, and stereophotography survey by Mason have made remarkable and memorable contributions to glacier mapping of the Himalaya. These surveys and expeditions contributed significantly in the following objectives:

(1) Mapping of unexplored valleys, peaks, passes and glacier terrain of the Himalaya;
(2) Correcting maps of the earlier Himalayan terrain through improved scientific instruments and advanced techniques;
(3) Many of these survey and expeditions led to precise maps of the glaciers and their surroundings which are of high accuracy and therefore be used to recognise the glacier changes on the basis of previous glacier snout maps.

Several Himalayan expeditions began the survey and mapping of glaciers during the Great Trigonometrical Survey (GTS) in the mid nineteenth century using plane-table surveying and heavy theodolite. For instance, Godwin-Austen mapped Kashmir Himalayan glaciers in 1860s and Ryall surveyed the Garhwal Himalayan glaciers during the 1874 to 1877. However, Strachey surveyed the Pindar glacier on 21 May 1848 during the journey of Rakas-Tal and Manasarowar and resurveyed the glacier on 15 October while returning from Tibet and recorded 98.5 feet (8 inches/24 hours) motion on Pindar glacier. Adolf Schlagintweit made one of the first ice-velocity measurements in the whole of Asia on Chungpar glacier, Nanga Parbat in 1856. In addition, Adolf Schlagintweit had painted Pindar and the Milam glaciers in 1855. Pocock’s successfully performed the plane-table survey of upper Mana valley in 1874 and surveyed maximum 22,040 feet height, this being so far the highest authenticated plane-table station during that time in the Indian Survey. The Geological Survey of India (GSI) initiated the monitoring of secular movements of the principal Himalayan glaciers as part of the programme of the Commission International des Glaciers during 1906-1908. Initially, GSI surveyed the twelve glaciers of entire Indian Himalaya. Plane-table glacier sketches were made for all the glaciers, showing the glacial geomorphic features. In addition, cairns were also built for further reference which was used by several scientists (e.g. Jangpangi, Vohra, Tiwari and many others) for the estimation of glacier variability.

However, the accurate delineation of glacio-geomorphic features above the snow-line had not been included in the SOI maps during mid nineteenth century. The surveyors were expressly told ‘not to waste their time surveying barren regions above 15,000 feet’. Therefore, several survey expeditions in the Himalaya (e.g. Baltistan, Garhwal Himalaya and Eastern Karakoram by Workman, Longstaff during 1900s) reported that glaciers had not always been delineated correctly during the Great Trigonometric Survey. Moreover, Mason (1928) corrected the location of Indira col on Workman’s map during his Shaksgam valley expedition (Figure 1).

Mason introduced stereo-photogrammetry mapping method devised by Captain Vivian Thompson photo-theodolite during Pamir triangulation in 1910s. In addition, Mason successfully demonstrated contouring of glacier terrain near K2 at a distance of 42 miles by terrestrial stereo-photogrammetry using Wild Phototheodolite in the mid 1920s. Bauer surveyed the Zemu glacier by terrestrial photogrammetry and prepared a large-scale glacier map in 1931 (Finsterwalder, 1935). Waymouth and his team effectively performed aerial survey over the Nanda basin, Garhwal Himalaya on 27 December 1939 and total twenty-nine verticals and one oblique photograph were taken during flight.

Mason observed during several Himalayan expeditions that representation of glacier-features on the SOI maps did not meet the requirements of modern science, especially in view of the fact that several important trade-routes traverse glaciers and passes were not mapped. Mason (1929) concluded that there is a need to first train surveyors in recognising the morphology of glaciers, their typical features and movements, before one can expect the glaciers to be surveyed and drawn correctly. In addition, Mason designed symbols, colour schemes and instructions for the representation of glacio-geomorphic features with special reference to Himalayan conditions on SOI maps. Initially, relief on topographic glacier maps was represented by black and white and colour hachure technique. The example of Zemu glacier maps illustrated in figure 2 and 3.

A large number of Indian and British surveyors thus used contemporary techniques and instruments for surveying unexplored Himalayan ranges and paved the way for future generations of explorers in mapping the Himalayan peaks and glaciated terrain in extreme climatic and high-altitude conditions. In the 1960s, the SOI published topographical maps of Himalayan glacier terrain on the basis of aerial photographs with limited fieldwork on a scale of 1:50,000. Mostly topographic maps which covers larger segment of Indian glaciers (e.g. Kashmir, Garhwal, Sikkim and Arunachal Pradesh) are defense series maps (DSM) and are restricted (Survey of India, 2005).

Since the beginning of the twentieth century, GSI have mapped several glacier snouts and surrounding glacio-geomorphic features such as Gangotri, Pindari, Milam, Shankalpa, Gor Garang, Trilokinath, Poting and many others for monitoring glacier recession. A literature review suggests that few large-scale topographic glacier maps have been prepared by the SOI since India obtained its independence in 1947. One of the maps was prepared by SOI for Meru bamak at 1:5000, Garhwal Himalaya, in 1977. In 1984 and 1995, SOI prepared maps at a scale of 1:10,000 for Chhota Shigri and Dokriani glaciers, respectively. These maps were prepared by the SOI during Interdepartmental expeditions. In contrast, more than a dozen glacier maps had been produced at a scale of 1:10,000 by the end of the nineteenth century, with the development of cartography as an independent discipline. Chaujar published first geomorphological map of Chota Shigri Glacier on 1:10,000 scale and plotted various landforms made by the glacier in 1991. It is noteworthy that in Norway alone as many as 24 glaciers were mapped more than once on a large scale between 1952 and 1996.

Glacier mapping using Remote Sensing and GIS

The continuous acquisition of the earth’s surface with satellite imagery with the start of the first Landsat satellite in the year 1972 marks also a new area for the glaciological research. The spatial resolution of about 80 m is precise enough to map the larger glaciers. Mapping of clean ice and smaller glaciers was facilitated with the launch of the Landsat TM sensor in 1982 which has a better resolution and can also record in the short wave infrared.

Recently, several studies on debris-covered glaciers have been attempted within Indian Himalaya. However, the mapping of debriscovered glaciers is very challenging as the margins of their tongues look sometimes similar to the surrounding debris without ice underneath. Debris-covered glacier mapping studies attempted on single or a group of glaciers. There is still no universal approach to map debriscovered glaciers precisely due to differences in regional/local landscape conditions such as (1) different size, shape and height of debris-covered glacier snouts, (2) vegetation cover, (3) surface ponds, (4) characteristics of debris-cover (medial moraine vs. thick debris cover on whole tongue) and (5) the amount of debris cover on ablation zone.

Recent Glacier Variation in Himalaya

The GSI is the leading institution who has recorded more than 30 Himalayan glaciers variability records based on ground survey. Recently, Bhambri and Bolch (2009) documented and analysed the length records of Indian Himalayan glaciers. The several studies by GSI based on field plane-table surveying, reveals that after mid 1990s recession of Gangotri glacier rate has decreased. Similarly, Meru glacier retreated at the rate of 27.5 m/a during 1977 to 1987, and from 1987 to 2000 it retreated 9.2 m/a which is less than previous observation. Parvati glacier (Himachal Himalaya) retreated at the rate of 168 m/a from 1962 to 2001. Almost 24% of the area of the Parvati glacier was deglaciated from 1962 to 2001, whereas Dokriani glacier (Garhwal Himalaya) lost about 11% of it previous area in 31 years (1962-1995).

It is noticeable that mostly basins in Himalayan regions were observed under glacier recession such as Chenab (~0.53%/a), Parvati (~0.56%/a), Baspa (~0.48%/a), clean ice glaciers in the Khumbu region and Sagarmatha National Park, Nepal (~0.12%/a) and Tamor river basin/eastern Nepal (~0.2%/a) from about 1970 to 2000. In contrast some advancing glaciers are found especially in the Karakoram region. In Himachal Himalaya glaciers <1 km2 lost 38% (~0.95%/a) of their area from 1962 to 2001-04 which reveals that small Himalayan glaciers are retreating at a higher rate. However, the absolute area loss is less than for the larger glaciers. Most of these studies used older topographic maps from SOI and compared these outlines with recent satellite imagery. Hence, these topographic maps are the valuable assets for glacier change studies. Unfortunately, several studies have shown that mapping of glacier areas on SOI topographical maps have serious accuracy issues. Therefore, glacier variation results derived from flawed topographic glacier maps cannot be explained by climate change and the topography alone^*. These inaccuracies are attributed mainly to cartography skills and the time of aerial photography acquisition during early winter months after snowfall (Bhambri and Bolch, 2009).

Variables influencing the glacier variability

Generally, the south-north and east-west irregularity of Himalayan glacier variability could be explained by the snow shadow zone effects, east to- west and south-to-north decreases in monsoonal intensity. However, the reaction of glaciers is influenced by many factors. Most important are the climatic variables temperature and precipitations. But also the wind and the solar radiation have a strong influence on the glacier, e.g. on snow redistribution and glacier melt. Non climatic factors are e.g. the distribution of supraglacial debris cover; altitude of accumulation zone; contributions from tributary glaciers. The glacier mass balance which can be obtained in the field but also through DEM differencing shows the direct response to climate change whereas area and length changes show a filtered signal only. This is mainly due to the fact that the glacier ice needs some time to build and flow from the head of the glacier to its snout e.g. high winter snow fall can effect the glacier snout years later. Glacier advances can be also caused by sudden sliding of glacier ice. These surges, which are common in the Karakoram but can also occur in parts of the Himalaya, can not be directly linked to climate.

Conclusion and Outlook

Topographic glacier maps are valuable assets to obtain information about glacier variability, glacier inventory, estimate mass balance, infer the morphometric status of glaciated regions and calculate changes in ice volume. However in India SOI maps are imprecise for glacier terrain in some instances. Declassified imagery from intelligent spy satellites, such as Corona imagery from the 1960s and 1970s, can be used for confirmation and improvement of the glacier outlines derived from the SOI maps. In addition, recent developments in geo-informatic software facilitate rectification, reprojection, and error detection and allow analysis of potential error sources. In the absence of topographic contour-based DEMs, only one study has estimated mass balance based on the geodetic approach. There exists a great opportunity to estimate mass balance from DEM generation based on old topographic maps and their comparison with recent high-resolution stereo data of the Indian Himalaya. However, due care is required while using old topographic maps, SRTM and stereo satellite data, which need validation using GPS and DGPS survey. Existing studies of Himalayan glaciers indicate that many glaciers are receding at different rates during the last decades. Thus, large-scale glacier maps should be prepared and updated regularly at scales of 1:50,000 to 1:25,000 for the monitoring of Indian Himalayan glaciers. In addition, topographic maps of glaciated terrain should be revised in order to optimise the prevention of hazards related to glacier changes. Furthermore, geoinformatics methods such as digital photogrammetry and airborne laser altimetry could be introduced for mass balance estimation.

References Bhambri, R. and Bolch, T. 2009: Glacier Mapping: A Review with special Reference to the Indian Himalayas. Progress in Physical Geography. 33, 672-704.
Finsterwalder, R. 1935: On the map of the Zemu Glacier. Himalayan Journal 7, 125-38.
Garwood, E. J. 1902. Notes on a Map of “The Glaciers of Kangchenjunga,” with Remarks on Some of the Physical Features of the District. The Geographical Journal 20, 13-24.
Mason, K. 1928: Note on Sir Francis Younghusband’s Urdok Glacier.The Geographical Journal, 71, 275-77.
Mason, K. 1929: The representation of glaciated regions on maps of the Survey of India. Professional Paper 25. Dehradun: Geodetic Branch, Survey of India, 18 pp.
Raina, V.K. and D. Srivastava, 2008. Glacier atlas of India. Bangalore: Geological Society of India, 316 pp.
Shekhar, M.S., H. Chand, S. Kumar, K. Srinivasan and A. Ganju. 2010. Climatechange studies in the western Himalaya. Ann. Glacio. 51(54) 105-112.
Survey of India 2005: National map policy. Retrieved 2 September 2009 from http://www.surveyofindia.gov.in/tenders/nationalmappolicy/nationalmappolicy.pdf
Authors Rakesh Bhambri: Wadia Institute of Himalayan Geology, Dehradun-248001, India
Tobias Bolch: Geographisches Institut, Universität Zürich, Switzerland
Ravinder Kumar Chaujar: Wadia Institute of Himalayan Geology, Dehradun-248001, India

Summary : A study of glacier mapping in Indian Himalaya.