A. V. Kulkarni

Glacial retreat in Himalaya using Indian remote sensing satellite data

Himalayas possess one of the largest resources of snow and ice, which act as a huge freshwater reservoir. Monitoring the glaciers is important to assess the overall reservoir health. In this investigation glacial retreat was estimated for 466 glaciers in Chenab, Parbati and Baspa basins from 1962. Expeditions to Chhota Shigri, Patsio and Samudra Tapu glaciers in Chenab basin, Parbati glacier in Parbati basin and Shaune Garang glacier in Baspa basin were organized to identify and map glacial terminus. The investigation has shown, an overall reduction in glacier area from 2077 sq km to 1628 sq km from 1962, an overall deglaciation of 21 percent. However, number of glaciers is increased due to fragmentation. Mean of glacial extent was reduced from 1.4 to 0.32 km2 between 1962 and 2001. In addition, number of glaciers with higher areal extent is reduced and lower areal extent has been increased between the periods. Small glaciarates and ice fields have shown extensive deglaciation. For example, 127 glaciarates and ice fields less than 1 km2 have shown retreat of 38 percent from 1962, possibly due to small response time. This means combination glacial fragmentation, higher retreat of small glaciers and climate change are influencing sustainability of Himalayan glaciers.

Estimation of recent glacial variations in baspa basin using remote sensing technique

The Himalayas has one of the largest concentrations of glaciers outside the Polar Regions. Various reports suggest that significant number of mountain glaciers is shrinking due to climatic variations. Monitoring of these glaciers is important to assess future availability of water resources in the Himalayan region. However, Himalayan glaciers are normally difficult to monitor due to the rugged, mountainous terrain. Therefore, images of Indian Remote Sensing Satellite were used to monitor glaciers in the Baspa basin. Investigations have shown the presence of 30 glaciers in the basin, with areal extent of 167 km2. Out of these, 19 glaciers, with areal extent of 140 km2 were selected to estimate retreat. Investigation suggests that almost all glaciers are retreating in the study basin and overall 19% deglaciation has been observed from 1962 to 2001. In general, altitude distribution appears to have significant influence on glacial retreat. Glaciers located around 5000 m altitude range are showing 24% loss as compared to 14% by glaciers located in altitude range higher than 5400 m. In addition, mean altitude of glacier terminus is shifted upward by 88 m, i.e. from 4482 to 4570 m in last 39 years. The glacial volumes were estimated using regression relationship between area and depth. The investigations have suggested that 19.10 km3 of glacial water stored in the 19 glaciers in 1962, has been reduced to 14.71 km3 in 2001, respectively, an overall loss of 23 percent in a period between 1962 and 2001. These investigations suggest that all glaciers in the Baspa Basin are reducing and in long term, such reducing trend can create scarcity of water in the region.

Recession of samudra tapu glacier, chandra river basin, Himachal Pradesh

Himalayas possess one of the largest resources of snow, ice and glaciers that act as a huge freshwater reservoir. Monitoring the glaciers is important to assess the overall reservoir health of the Himalayas. Samudra Tapu is one of the largest glaciers in Chandra basin of district Lahaul and Spiti, Himachal Pradesh. Based on the field investigations and the remote sensing techniques. features such as accumulation area, ablation area snowline/equilibrium line, moraine-dammed lakes and permanent snowfields were mapped. The glacial terminus was identified using moraine-dammed lake, as lake is located at down streamside of the terminus. The total recession of glacier during the period of 38 years (1962–2000) is about 742 m with an average rate of 19.5 m/yr. In addition, glacial extent is reduced from 73 to 65 km2 between 1962 and 2000. suggesting overall deglaciation of 11%. During field investigation. three stages of glaciation using terminal moraine were identified. These moraines were mapped by merging LISS-II1 and PAN data. At the peak of glaciation. the glacial terminus was extended 3.18 km downstream of terminus position in year 2000. Total area during peak of glaciation period has been observed to be 77.67 km2, which is 12.67 km2 higher than the present glacier extent.

Snow and glacier melt runoff model to estimate hydropower potential

Himalayan region has high concentrations of mountain glaciers. Large extent of this region is covered by seasonal snow during winter. Runoff generates from melting of these snow and glaciers is one of the important sources of water for the Himalayan Rivers. Glaciers and snowfields are distributed throughout the Himalayas and form a source of numerous streams. Due to steep slopes, all such streams have potential sites for hydropower generation. If this potential is fully utilized, it will help in generating power from environmentally friendly Run-of-River (RoR) hydropower stations. Considering these aspects, a stream flow simulation model was developed for small streams. This will help in estimation of average seasonal unrestricted hydropower potential of snow and glaciated streams for winter, summer, monsoon and autumn seasons. Information generated through remote sensing technique as glacier, permanent snow cover, seasonal snow cover, altitude of snow and glaciers were used in conjunction with daily maximum and minimum temperature, rainfall and discharge. The model was developed for Malana nala located in Parbati River basin near Kullu in Himachal Pradesh. It was validated at adjacent Tosh nala in the same basin. Seasonal runoff computed from the model is comparable with observed data for all seasons except Monsoon. Good results in autumn, winter and summer seasons demonstrates usefulness of runoff model to assess hydropower potential of snow and glaciated streams and therefore, the model was applied to ungauged Sorang Gad and Kirang Khad. In winter runoff was estimated as 1.8 and 1.69 cumecs for Kirang Khad and Sorang Gad, respectively. This is important, as viability of hydropower station depends upon winter stream runoff. These results suggest that the model is useful tool to assess initial estimate of hydropower potential for large number of snow and glaciated streams, for which no hydrological data is available.

Glacier inventory in Himachal Pradesh using satellite images

A total of 125 glaciers covering an area of 1896 sq. km. were mapped on 1:250,000 scale in Himachal Pradesh using satellite images. The areal extent obtained from satellite images was found to be comparable with that from field estimates for eight glaciers for which data are available. This suggests that remote sensing can provide glacial areal extent similar to ground-based methods. Depth of an individual glacier was inferred indirectly by using its relationship with areal extent and geomorphological characteristics, as suggested by Muller (1970). These characteristics were estimated by using satellite images. The analysis suggests that the water equivalent of the glaciers in Himachal Pradesh is about 165 cu km. It is seventeen times more than the storage capacity of the Govind Sagar. This estimate will get revised when other snow/ice features as permanent snow field, ice apron, hanging glaciers and rocky glaciers are mapped. Mapping on larger scale, say 1:50,000, will lead to a further revision as many smaller glaciers and other features will get mapped.

MORAINE-DAMMED LAKES STUDY IN THE CHENAB AND THE SATLUJ RIVER BASINS USING IRS DATA

Moraine-dammed lakes are normally formed near glacier terminus. These lakes can burst due to excessive melting and can cause floods in the valleys. Many such floods have been reported in the Himalayas and other parts of the World. In this paper, an inventory of these lakes in the Satluj and the Chenab basins has been reported. During the investigation, 22 lakes in the Satluj and 31 lakes in the Chenab basin were mapped. In the Chenab basin, two lakes are of very large size, their areal extent is 105 and 55 ha, located in toposheet number 52 HI 1 and 52H02, respectively. These lakes were selected for detail monitoring.The lake near the Geepang glacier, is located in toposheet number 52H 02 and its area was 27 ha in 1976. Using the satellite data, areal extent of the lake was monitored. The lake area was almost doubled to 55 ha in 2001. This suggested that, lake size is constantly increasing and it can cause outburst flood. The maximum possible depth of lake was estimated by taking the average difference of maximum and minimum height of moraine dam from the Survey of India toposheet. By considering the average depth, the volume of the lake water and the instantaneous discharge of 350 mVsec were estimated. This is large discharge for a small stream like the Geepang Gath and it can damage many civilian and defense establishments. Therefore, further detail field investigations of this lake are needed to assess threat potential and to develop strategy to avoid this flash flood.

APPLICATION OF DIGITAL ELEVATION MODEL AND ORTHOIMAGES DERIVED FROM IRS-1C PAN STEREO DATA IN MONITORING VARIATIONS IN GLACIAL DIMENSIONS

An attempt has been made to study variations in the glacier extent over a period of time using digital elevation model (DEM) and orthoimages derived from IRS-1C PAN stereo pairs of 1997–98 and topographical map surveyed during 1962–63. DEM and orthoimages have been generated using integrated software developed for processing of IRSIC/ID panchromatic stereo data using the softcopy photogrammetric workstation. Case studies of two glaciers, i.e. the Janapa garang and Shaune garang glaciers of the Basapa basin, a sub-basin of Satluj River in India, have been presented here. Generation of DEM has been followed by the estimation of its accuracy. PAN images were interpreted for identification of the snout of the glaciers. The geographical locations of the snouts on the images were compared with the location as mapped on the topographical map of the study area. To verify satellite observations, field investigations were carried out at Shaune garang glacier area. The Janapa garang and the Shaune garang are observed to have retreat of 596m and 923 m respectively. Reduction in the thickness of ice in the deglaciated part of the Shaune garang glacier was estimated on the basis of change in the elevations of the glacial surface from 1963 to 1998.