Glaciers of Himachal Himalaya:
Geological history of Earth indicates that glacial dimensions are constantly changing
with changing climate. During Pleistocene the earth’s surface has experienced repeated
glaciations over a large land mass. During the interglacial period, climate was
warmer and deglaciation occurred on large scale. This suggests that glaciers are
constantly changing with time and these changes can affect the discharge of most
of the Himalayan Rivers. Therefore it is important to carry out the investigation
for snow and glaciers for the proper management of Himalayan water resources.
Keeping in mind this view, Space Applications Center had initiated a programme for
the mapping of glaciers and permanent snowfields in the Satluj basin. Using IRS
satellite data inventory was completed for the Satluj basin right from its orgin
in Tibet catchment. Similar investigations were carried out in the Chenab basin
in Himachal Pradesh. The mapping was carried out on 1:50,000 scale using LISS III-
High Resoultion Satellite Data.
Seasonal Snow Cover Variation during the year 2004, 2005,
2008 & 2009 in Beas, Satluj, Ravi & Chenab Basins in Himachal Pradesh:
The state of Himachal Pradesh receives winter precipitation in the form of snow
in the higher altitudes and about 1/3rd of the total geographical area remains under
thick snow cover during the winter season. Most of the major rivers and the perennial
streams originating from the Himalayas depend upon the seasonal snow cover for their
discharge dependability. Keeping this in consideration, using High Resolution AWiFS
satellite data the analysis was done for assessing the variation of seasonal snow
cover in three winter months i.e. January, March and April for the years 2004 &
2005 and 2008 & 2009 in the state of Himachal Pradesh. The investigations were completed
at Space Application Center Ahmedbad. The results obtained from the analysis suggest
that there is an overall increase in the total area under snow in each basin in
the year 2005. Thus it is observed that there is an overall increase in the total
area under in all the basins observed in the year 2005 for the months January, March
and April as compared to the year 2004. Likewise an overall reduction in total area
under snow cover during the month of February 2009 was observed where as March and
April shows an increasing trend in 2009 than 2008.
Monitoring of Glaciers of Baspa Basin:
Himalaya has the largest concentration of glaciers outside the Polar Regions. Predominantly
Himalayan glaciers are valley type in morphology and most of them are covered by
debris. Therefore, they provide unique and complex interaction with climate. Melt
water from these glaciers forms an important source of water for most of the North
Indian Rivers. Based on the recent observations on the Himalayan Glaciers, it is
observed that most of them are retreating. Thus monitoring of these glaciers would
be helpful to assess the future availability of Himalayan water resources. In the
present study, glaciers of the Baspa and Spiti sub catchment of Satluj River basin
have been monitored.
On the basis of the updated inventory of the glaciers in the Baspa basin a total
of 30 glaciers could be mapped. Out of these 19 glaciers were selected to estimate
glacier retreat. Investigation reveals that almost all the glaciers are receding
and an overall 19% deglaciation is observed from 1962 to 2001. Glacier located around
5000m have shown 24 % loss as compared to 14% for those located on the altitude
higher than 5400 m and the mean altitude of the glacier terminus is shifted upward
by 88m i.e. from 4482 to 4570. In the last 39 years almost 19% glaciated area is
reduced in the Baspa basin. In addition, in the month of December January snow melting
was observed in altitude range as high as 4800 m which will have a profound effect
on the stream run off pattern of many glaciers and snow fed streams.
GLACIER LAKE OUTBURSTS FLOODS (GLOF):
Glacier outbursts floods caused by moraine dammed lakes are a common feature in
the glaciated terrain in the world. The bursting of these lakes increases the discharge
of the stream causing flash floods in the downstream areas and causes huge loss
of life and property. Many events of such outbursts floods have been reported in
the North America, Europe and in the Himalayas (Clark & Mathews, 1981, Deslognes
et al 1989 ) . So far in the Himalayan region the bursting of such lakes have been
reported from Manalsu region , Central Nepal and in Bhutan (Gansar ,1983).However
no systematic records of glacier lake outbursts from Indian Himalayas is available.
During the investigation for the snow and glaciers in the Himachal Himalayas, an
attempt has also been made to delineate all such lakes formed in the glaciated region.
A total of 38 lakes could be mapped in the entire Satluj basin ,out of which 14
lakes falls in the Himachal Himalayas where as the remaining lakes fall in the Tibet
Himalayas and 55 lakes have been delineated in Chandra basin out of which 5 are
supra glacier lakes.
Monitoring of Glaciers of Spiti Basin
The monitoring has been done using 1962 as the base layer from Survey of India topographic
maps and the glacier layers for the year 2001 and 2007 based on the satellite data.
On comparison, it is found that 188 glaciers in 1962 have increased to 217 in 2001,
which may be due to fragmentation of large sized glaciers increasing the small glaceris.
This is evidenced by the fact that 5 glaciers with area more than 10 sq km in 1962
have been reduced to only 2 glaciers in 2001. Similar trends have been observed
in case of glacier with areal range between 5-10 and 3-5 sq km. Likewise, the small
sized glaciers with area less than 1 sq km shows an increase in their numbers from
556 (2001) to 621(2007) and loss of area of about 5%, whereas glaciers with aerial
range of 3-5 sq km shows minimum deglaciation of the order of about 4% during this
period. The large sized glaciers do not show much variation in their number between
2001 & 2007, but shows a deglaciation of the order of about 21% during this period.
In general an overall reduction of about 11% has been observed during the monitoring
period of 2001 to 2007.Thus based on the investigations, it is concluded that the
large sized glaciers seems to be worst affected in the basin with the result the
glaciers of the valley can be said to be in reducing phase and such reducing trends
may create scarcity of the water in the region in future.
