Glacial Response to Environmental Changes in Nubra Valley
By : Prof. Rajinder K. Ganjoo
The 114 glaciers of Nubra valley, Karakorum, Ladakh of various dimensions are divided
into seven classes of 5km interval each, based on the length of the glacier. Almost
52.6% of the glaciers are of the size less than 5 km and 31.5% of the total glaciers
are between the size of 5 and 10 kms. This clearly suggests that Nubra valley is
occupied by a large number of small glaciers. Majority of largest glaciers are confined
to the southeast segment. The SE facing glaciers comprise nearly 84% of the total
glacier area of 114 glaciers. The study of 114 glaciers has been divided into two groups of 84 and 30 glaciers. The change in the area of first group comprising 84
glaciers has been made for the years 1989 and 2001, the time series for which the
satellite imageries are available for the area. The change in the area of 84 glaciers
with effect from 1969 could not be studied due to the non-availability of Survey
of India (SOI) topographic sheets covering these glaciers. The second group comprising
30 glaciers has been studied in detail with respect to change in the area for the
years 1969, 1989 and 2001. The selection of 30 glaciers for their detail study on
change in area since 1969 was primarily because of the availability of SOI topographic
sheets covering these glaciers in the Nubra valley.
Twenty-five glaciers, out of the 84 glaciers in Nubra valley show gain in area from
1989 to 2001. Good percentage (24%) of the glaciers in this category is oriented
in east, followed by northwest and west directions that are represented by 16% glaciers
each of this category. Twelve percent of glaciers of this category are in southeast
direction, followed by 8% each in north-northwest and southwest directions, whereas
4% each of glaciers are in northeast, south southeast and south-southwest directions.
The glaciers in this category occupied an area of 1096.39 sq km in 1989 that enhanced
to 1104.33 sq km in 2001.
Twenty-six glaciers, out of 84 glaciers in Nubra valley are those who vacated the
area between 1989 and 2001. The dominating orientation of glaciers in this category
is in southeast (23%), followed by northeast (19%). Equal percentage (15% each)
of glaciers belonging to this category is oriented in south and east directions.
Besides, 8% each is represented by north, south-southwest and southwest directions,
whereas 4% of glaciers are oriented north-northeast. The glaciers in this category
have reduced in area from 330.542 sq km in 1989 to 326.007 sq km in 2001.
Thirty-three glaciers, out of 84 glaciers show no change in their area between 1989
and 2001. The glaciers occupy an area of 1733.219 sq km from 1989 to 2001. Dominating
percentage of glaciers belonging to this category are oriented in west (31%) followed
by north (15%). The other directions represented by this category are northwest
(12%), northeast (9%), east (9%), southeast (9%), south (6%), south-southwest (6%)
and southwest (3%).
Thirty out of 114 glaciers of the second group are those who have record since 1969.
The critical comparative evaluation of glaciers marked on the SOI topographic sheets
of 1969 with Landsat imagery of 1989 and LiSS-III imagery of 2001
shows that three
glaciers have gained area since 1969, eight glaciers have gained area from 1969
to 1989 and then vacated the area from 1989 to 2001, five glaciers show vacation
of area from 1969 to 1989 but subsequently gain in area from 1989 to 2001, seven
glaciers show constant vacation of area from 1969 to 2001, three glaciers show gain
in area from 1969 to 1989 but subsequently no change in area from 1989 to 2001,
whereas four glaciers show vacation of area from 1969 to 1989 and subsequently no
change in area from 1989 to 2001.
The changes in the glaciers of Nubra valley are varied and complex. Some glaciers
show change in length with respect to area whereas some glaciers show variation
in area and not in length. In absence of intensive weather data from the Nubra valley,
it would be premature to conclude upon the causes for such complex and varied changes.
However, it is beyond doubt that glaciers of the Nubra valley do not show much change
in their length and area between 1989 and 2001 compared to the time period 1969