Expedition in the Zeravshan Glacier

Expedition in the Zeravshan Glacier

The Agency for Hydrometeorology of the Committee for Environmental Protection under the Government of the Republic of Tajikistan, during the implementation of the "State Program for the Study and Preservation of Tajikistan's Glaciers for 2010-2030," made every effort to achieve the desired results.

It should be noted that in accordance with paragraph 5.2 of the State Program for the Study and Preservation of Tajikistan's Glaciers for 2010-2030, specialists from the Agency's Center for Glaciology conducted expeditionary work on the Zeravshan Glacier on October 15-26, 2019. The expedition was attended by specialists of the Agency of Hydrometeorology Rakhmonov R. - head of the Glaciology Center, Pirov A. - head of the department for the study of snow-avalanche processes, Nazirzoda K. - chief specialist of hydrography and expedition, as well as Malaev K. - head of the Dehavz station of the Gorny Matches Sogdian region area.

The large dendritic Zeravshan glacier lies in the upper reaches of the valley of the same name between the southern slope of the Turkestan ridge and the northern slope of the Zeravshan ridge, so the exposure of its individual sections is very diverse: southern, southeast, southwest, western.

The glacier consists of a main stream and about two dozen tributary glaciers. Zerafshan glacier begins at the junction of the ranges of Turkestan, Alai and Zerafshan. The glacier flows first to the south, and then near the per. The match is turning west. The firn region of the Zeravshan glacier is relatively small; the glacier receives its main food due to tributaries that originate on the southern slope of the Turkestan ridge.

These are complex valley glaciers that lie in well-developed transverse valleys — the Farakhnau, Tolstova, Skachkova, Miramin and other glaciers. The left tributaries descending from the northern slope of the Zerafshan ridge are small and steep. The relatively narrow and long tongue of the Zeravshan glacier with an average slope of about 8 ° descends along the valley between the Turkestan and Zeravshan ridges to a height of 2810 m and from the grotto of which the Zeravshan River originates. Moraine deposits, thick cracks, dips are characteristic of the surface of the glacier tongue , wells and other ablative landforms.

According to the plan of work of the Center for Glaciology of the Agency for Hydrometeorology, from 15.10.2019 to 20.10.2019, the employees of the Center for Glaciology carried out expeditionary work to examine the Zeravshansky glaciers. The program of work included: tachymetric survey of the tongue of the Zeravshansky glacier in order to determine the boundaries of the frontal zone of the glacier. The magnitude of the melted severed glacial section of the so-called "dead ice". The current location of the glacier tongue.

Meteorological observation: air temperature in the area of ​​Zerafshansky glaciers, cloud cover, precipitation, wind direction and speed, atmospheric pressure, air humidity in terms of 6 hours, 9 hours, 12 hours, 15 hours, 18 hours. Hydrological observations: measurement of water discharge in the estuary (grotto) of the Zeravshan rivers in terms of 8 hours, 18 hours. Water sampling for chemical analysis at the end of work. Devices: thermometer - sling, stopwatch, water meter river, aneroid barometer, anemorumbometer.

At the time of the survey, conducted on 10/19/2019, the area of ​​“dead ice” that had been separated from the tongue of the glacier for the last decade was completely absent. The linguistic boundary of the glacier receded from the previous borders of the glacier 1979,1991,2009 by an average distance of 1,700 m. The boundary of the final part of the glacier is clearly located between the gorges of the right bank of Frachnou and the left bank of the Nazarailok Valley.

According to estimates for 40 years at a distance of 1700 meters. The glacier retreat rate, taking into account the already melted section of “dead ice”, was 43 m / year along the entire front of the glacier tongue. According to the 2009 survey, the main part of the glacier was located almost in the middle part of the glacier tongue. According to the survey in 2019, the grotto of the source of the Zeravshan River moved to the right and is located 180-200m from the starboard side of the glacier tongue.

 Pig. 1 Zerafshansky Glacier 1979, 2009 and 2019

Matchinsky glaciation knot

Zeravshansky Glacier

The last visit to the glacier, the survey of its final part was carried out on July 17, 09, for the period from the reference point “B” to the border of the tongue of the grotto of the main part, the distance was 1100 m. Three transition points during the survey of the glacier were located on the site of “dead ice”. Covered with moraine deposits of the severed language zone of almost the final part of the glacier located in the right-bank part of the glacier. The bridge of the severed part reached a width of 180-200 m. The area of ​​the “dead ice” site was 385.4 thousand m2. The volume according to the calculated data was 11562.0 m3.

Conclusion:

Based on the observations made, an unambiguous conclusion can be made. The Zeravshansky glacier continues to retreat. The area of ​​melted ice, taking into account areas of “dead ice” both in the right-bank and in the left-bank part, according to surveys conducted in 1979,1991,2009,2019, amounted to 1.34 km2. According to estimates, the volume of melted ice was 2.04 km3. The progress of the continuing retreat of the end of the glacier’s tongue is indicated by numerous cracks, dips, and wells located both on the linguistic part and on the stem part of the glacier’s body.

According to estimates, in the coming decades there is reason to believe that the separation of its right tributary of the Skachkov glacier will begin from the body of the Zerafshan glacier. In the region where the Skachkova glacier tongue is severed, the cross-cutting of the Zeravshansky glacier trunk by the watercourse from the Skachkova glacier will take place and the final part of the Zeravshansky glacier will gradually transform into a “dead ice” zone.

It should be noted that at the time of the survey of the middle part of the glacier, the collapse of one of the left-bank tributaries of the Zeravshan glacier was revealed. The collapse of the ice masses at the slope glacier occurred 10 km above the tongue of the Zeravshansky glacier from a height of 3700 m. Judging by the state of the ice fractions, the collapse occurred in the period July - August 2019.

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