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Poster Session
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Mapping of Bara Shigri Glacier, H. P. using
Digital Image Processing Techniques
A. Jeyaram, Y. V. N. Krishna Murthy and D. S. Srinivasan
Regional Remote Sensing Service Centre
Department of Space, Nagpur 440 010 - India
Abstract
Glacier are perennial source for more than 19 rivers which flow from lofty mountain ranges of Himalaya in North India. These glaciers act as buffers with a regulated runoff in the rivers. The runoff from the glaciers in any part of the year may be less but collectively for a year may be less but collectively for a year may be more than that of the years precipitation. With the threat of global warming looming large, scientists across the world are trying to study the impact of the warmer earth on glacier system. Since the glaciers are mostly found inaccessible and in rugged terrain in the Himalayas, the use of remotely sensed data plays a crucial role by providing synoptic view in multispectral mode. different wave length bands are sensitive to the varying properties of lice/snow. The area covering Bara Shigri glacier forming part of Chandra Basin, Himachal Pradesh, has been made to map the major glacial features using digital techniques and assessed the application potential of IRS LISS II data for glacial mapping on an operational basis.
The change in the digital number (DN Value) of IRS data long the glacier transect from snout area to accumulation area have been analysed. Various digital image processing techniques have been carried out to delineate glacier boundary, accumulation area, equilibrium line, ablation area etc. The image ratio techniques provided major glacier units. The digital elevation model (DM) has been generated and false colour composite of band 4,3,2 and colour coded ratio output have been draped over DEM. Te mapping of the major glacier features are not clearly discernible in the FCC of IRS LISS II data probably due to 7 bits quantization level which due to 7 bits quantization level which shows mils change in gradient of DN values from accumulation zone to ablation zone. The rationing techniques of appropriate bands enhanced glacier features bands enhanced glacier feature which could be mapped easily.
The generation of digital terrain model (DTM) by draping colour coded ratio output and false colour composite provided new dimension for glacier mapping by delineation of glacier units and superimposition of selective contour over the glacier, permitted the correlation of elevation with glacier features.
Introduction
The surface of the glacier receives mass as snow and losses by ablation. The hydrologic characteristic of the glacier, its thickness, volute, mass balance, nature, rate of movement and response to climate change are the primary interest of glaciologist and hydrologists. Glaciers are found in the high altitudes of Himalayan ranges in India which from the perennial source for most of the north Indian rivers. The data compiled from 1812 by Mayewski and Jeschaka (1979) on the glacier history of high Asia indicate a peak position of the glacier during the year 1850 and a general state of retreat from that time. The pindari glacier in Kumaon region has retreated by over 2.6 km since 1958. The Garhwal Himalayas have some of the longest glaciers such as Gangotri in which the snout has retreated by 1100 m. Bara shigri and Chota Shigri glaciers of Himachal Pradesh have shrunk by 1 to 1.5 km 1850.
Since the glaciers are mostly found inaccessible in rugged terrain of Himalayas, the remotely sensed data plays a crucial role by not only providing synoptic view but also provides information in various wavelength ranges to study the glaciers in details. Ice/snow are easily discernible from the satellite images in the optical range. Different wavelength bands are sensitive to the varying properties of ice/snow.
Sutdy Area
The area covering Bara Shigri glacier in Hiamchal Pradesh, north India in bounded by latitudes of 320, 05' - 320 20' N and longitudes 770 28' - 770 - i) has been taken for digital image processing. Bara Shigri glacier form part of Chandra river basin. The elevation is ranging from 3800 m above MSL to 6637 m above MSL and the entire catchments is oriented towards ESE NNW direction. Fairly good vegetation is found in lower altitudes of the study area which extends as bushes in the higher altitudes. During winter, entire in summer close to 50% of the are a becomes snow free. The entire area is divided into 5 elevation zones.
Figure 1 Location Map
Figure 2 Altitude Zones and Mean Hypsometric Zones
Data Inputs
The following data are used for the present investigation :
- Satellite data
IRS LISS II Path : 29 Row : 45 Q:A1
acquire on 21.09.1992.
- Topographical map
52 H (1:2, 50,00 scale)
52 H/12, H/16, (1:50,000 scale)
Methodology
The area covering Bara Shigri Glacier has been extracted from IRS LISS II digital data and processed for glacial mapping. IRS LISS II data has been geocoded using topographical maps. Band 4 has been scaled from0-127 to 0-255 by linear enhancement technique. The enhanced band 4 has been used for rationing with band 2. The resultatnt image is colour coded for various glacier features. The digital elevation model ahs been generated using SOI topographical map. False colour composite and the ratio images are subsequently raped on the DTM for further analysis. The digital rerrain model of rationed image ha been used for correlation of elevation with different glacial features.
Figure 3 Flow Chart of Methodology
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