Grant project IRN AR08856470
Project manager: Kaldybayev Azamat, PhD
Download the project final report: Region-Wide Glacier Mass Balance Assessments and Inventory of Active Rock Glaciers in the Zhetysu Alatau Using Remote Sensing Data (REPORT)(NO.GR 0120РК00).pdf
Scientific research work (SRW) is carried out within the framework of a state order for the implementation of a scientific and/or scientific and technical project under budget program 217 “Development of science in the priority area of information, communication, and space technologies,” IRN AR08856470.
The relevance of the research is determined by the need to assess and monitor the dynamics of changes in glaciers and rock glaciers, as well as the mass balance of glaciers throughout the entire mountain range, where ground-based data is practically unavailable. The results of the research will enable the study of the country’s water resources in the context of climate change.
The aim of the work is to assess changes in glacier heights and calculate the geodetic mass balance on a regional scale with high temporal and spatial resolution, as well as to inventory active rock glaciers in the Zhetysu Alatau using optical and radar images.
Expected results:
For 2020: Database of archived and current remote sensing data of various types and resolutions for the Zhetysu Alatau region. Detailed review of previous studies.
For 2021: Identification and mapping of glaciers and rock glaciers, determination of the equilibrium line altitude (ELA) above the Zhetysu Alatau.
For 2022: Assessment of changes in the altitude and mass balance of glaciers on a regional scale for the Zhetysu Alatau based on Earth remote sensing data.
Results achieved:
In 2020, archival and current remote sensing data of various types and resolutions were selected for the territory of Zhetysu Alatau. A detailed literature review on the main objectives of the project was carried out, published materials on the study of the glaciers mass balance, active rock glaciers and the glacier area change were analyzed. A database of archival and actual data of remote sensing of various types and resolutions has been created for the study of the Zhetysu Alatau glaciers.
In 2021, glaciers were mapped from remote sensing data using a semi-automatic band ratio technique. The rock glaciers of the Zhetysu Alatau have been identified and mapped using high-resolution Google Earth optical and SAR imagery.
Glaciers were detected in all seven river basins for Zhetysu Alatau using Landsat satellite images from 1989 to 2020, at the end of the ablation period (end of the summer season). On the basis of natural and climatic characteristics (the presence of clouds, fog, the amount of snow cover, etc.), a selection of images suitable for analysis was carried out, namely, for 2001, 2012 and 2016. The area of glaciers on the selected satellite images was determined by the semi-automatic band ratio technique. Detailed analysis was made of the rate of shrinkage in the glaciers area.
As a result, 897 glaciers were identified in 2001, 842 in 2012 and 813 in 2016, which were listed in the Catalog of Glaciers with a total area of 517.4, 453.7 and 414.6 km2, respectively. The largest area of glaciers in the Zhetysu Alatau is occupied by glaciers up to 1.0 km2 in size for all three periods of time. In total, about 90% of the glaciers of the Zhetysu Alatau are glaciers with an area of up to 1 km2. Glaciers with an area of more than 1 km2 make up more than 10%, but in general, in the covered area of the glaciers of the Zhetysu Alatau, it is 60%.
The total reduction in glacier area between 1956 and 2001 was -36.4 ± 2.8% or 296.2 ± 8.3 km2, decreasing from 813.6 km2 to 517.4 ± 14.5 km2, while how the number of glaciers decreased from 985 to 897. During the period from 1956 to 2016, the area of glaciers decreased by – 49 ± 2.8% or 399 ± 11.2 km2 (from 813.6 km2 to 414.6 km2), the number of glaciers decreased from 985 to 813.
In the period from 2001 to 2012, the number of glaciers in Zhetysu Alatau (Kazakhstan part) decreased from 897 to 842, and in the period from 2001 to 2016 from 897 to 813 glaciers. In the period from 2012 to 2016, the total area of glaciers decreased by 8.6 ± 2.8% and decreased from 453.7 km2 to 414.6 km2.
In addition, in Zhetysu Alatau in 1956 there were 385 glaciers with an area of less than 0.1 km2. In 1956, the total area of these glaciers was 18.9 km2, in 2001 their area decreased to 5.1 km2, in 2016 to 3 km2.
Interferometric processing by the SBAS (Small Baselines) method of radar data was carried out. Zones of horizontal and vertical displacements are revealed. Zhetysu Alatau rock glaciers have been identified and mapped using high-resolution Google Earth optical and SAR imagery. Using the results of radar interferometry, a classification of active rock glaciers was carried out according to their displacement velocity. For general statistics, both inactive and relict rock glaciers are included.
The study provided the first comprehensive up-to-date documentation on the characteristics of rock glaciers in the Zhetysu Alatau.
A total of 848 rock glaciers were identified with an area of more than 83.4 km2 and with an average lower limit at an altitude of 3018 m above sea level; the average area of individual units was 0.10 km2. The largest rock glacier in the area has an area of 1.53 km2, while the smallest rock glacier has an area of about 0.003 km2. The displacement rate of rock glaciers in the Zhetysu Alatau reached 252 mm/yr.
Most of them had a northern (northern, northeastern, northwestern) orientation, which indicates the important role of solar insolation in their formation and preservation. Slopes with lower PISR favored the development of rock glaciers. The height of rock glaciers generally increased from east to west and decreased from south to north, indicating the effect of latitude and longitude on rock glacier height.
The most amount of rock glaciers were found in the Karatal river basin – 238 pieces with a total area of 17.3 km2. The lowest rates of glaciers both in number and area are in the Yrgaity River basin – 47 pieces with a total area of 4.2 km2. Perhaps this is due to the fact that the territory of the Yrgaity river basin itself is the smallest. Also, in this basin there are the least glaciers. Although Karatal basin is the leader in terms of quantity, rock glaciers in the Lepsy-Baskan basin predominate in terms of area.
This inventory has provided a baseline dataset for further studies of rock glaciers as a reservoir, as well as permafrost for slope instability, water resources, and emissions.
In 2022, an assessment was made of elevation changes and mass balance of glaciers on a regional scale for Zhetysu Alatau based on remote sensing data. Our method for calculating the geodetic mass balance of glaciers is based on the DEM differencing. The elevation difference arising from the different possibilities of penetration through the surface of the C-band and X-band microwave radiation is taken into account. The method used includes the stages of horizontal co-registration of compared digital models based on reference points obtained over stable regions and calculation of elevation changes.
According to our data, the regional average value of the mass balance per year for the Zhetysu Alatau glaciers averaged -0.44 m w.e. a-1. These mass balance indicators are in good agreement with the GLIMS data. It has been established that the fastest mass loss occurs in the Yrgaity and Tentek basins, where it is -0.59 w.e. a-1. and -0.55 w.e. a-1, respectively. And in the Aksu, Lepsy and Karatal basins, the relatively slowest loss is -0.35, -0.38 and -0.40 w.e. a-1, respectively. The rate of mass loss correlates well with the loss of glacier area.
For a more detailed analysis of the reason for the sharp reduction in the glacier, we analyzed climate data. Estimates of air temperature trends showed that the temperature rise occurs at all stations in all seasons and months of the year. Rates of temperature change are observed in the mountainous areas of Zhetysu Alatau (Kogaly MS), where the average rate of change was 0.12 ºС/10 years. Trends in summer temperature changes (June-August) showed that in mountainous and foothill areas they have the highest values and range from 0.19 ºС/10 years (Kogaly MS) to 0.25 ºС/10 years (Taldykogan MS). An analysis of trends in change has shown that a steady increase in air temperature has been observed in the study area over the past decades.
In the trends of the average annual precipitation over the territory, there is a tendency to an increase in annual precipitation (up to 11 mm / 10 years), the only exception is the Sarkand MS, where there is a slight decrease in precipitation. At the same time, in the last years of 2019 and 2020, there was a deficit of atmospheric precipitation at the three Taldykorgan, Usharal and Kogaly stations.
It has been established that climatic conditions play a main role in the state of glaciers. The location of the region under study on the periphery of the Tien Shan mountain system has less favorable climatic conditions than the inner ranges. Two main climatic factors, a significant increase in temperature and a slight change in precipitation, played a main role in the negative balance of glaciation in the Zhetysu Alatau.