Institute of Hydrometeorology

Tergi River Basin

Glacier Gergeti

Glacier Gergeti is the large glacier of the r. Tergi glacial basin. As a result of specifying the contours, the shape of the contour of the Gergeti glacier has changed significantly. According to the satellite image of September 1, 2010, in the contours preserved in the GLIMS database, most of the glacier plateau belonged to the Gergeti Glacier. Using the DEM, the watershed was specified as a result of the use of the height isolines - hypsometric curves marked with a 30 m grid. This caused correction of the picture and a significant part of the plateau belongs to the Devdoraki glacier.

Stefantsminda meteorological station is located near the Gergeti glacier. Table 4 shows the mean summer temperatures (T_mean) for two periods and the differences between them ΔT_mean calculated from the data of this station. There is an increase in all three months, with an average of 1.10 ⁰C in summer.

These data confirm that the rapid degradation of the Gergeti glacier is caused by modern climate change. On the other hand, glacier retreat data is an effective indicator of current climate change and its acceleration in time.

Average air temperature data according to Stefantsminda weather station

The calculations show that the non-linear retreat of the Gergeti glacier is described by the parabola curve:

Y = 0.1966x²+ 12.134x + 8.0718

The length of the Gergeti glacier according to 2022 data is 6718 m. According to satellite data, the retreat of the Gergeti glacier from 1977 to 2022 was 943.2 m. The sum of these two numbers, 7661.2, should equal the trend equation, and then the resulting quadratic equation should be solved:

0.1966x²+ 12.134x + 8.0718 = 7661.2
That is
0.1966x²+ 12.134x = 7653.1

The positive solution of this equation is approximately 168.8391≈169. This result means that if the current trend of retreat continues, the Gergeti Glacier will probably melt completely in 169 years, or in 2146 (the starting point is 1977).

Also, according to ground-based data from field observations, the retreat of the Gergeti Glacier from 1977 to 2022 was 893 m. The sum of these two numbers, 7611, should equal the trend equation, and then the resulting quadratic equation should be solved:

0.3849x² + 3.8386x - 17.481=7611
that is
0.3849x²+ 3.8386x= 7628.5

The positive solution to this equation is approximately 135.8833≈136. This result means that if the current trend of retreat continues, the Gergeti glacier is expected to melt completely in 136 years, or in 2113 (the starting point is 1985).

A comparison of the analytical forms of the SRS and field data shows that the ground-based data of the TDS and field observations of the Gergeti glacier are in good agreement with each other.The comparison of these equations and consequently of the obtained analytical equations shows that they are in good agreement with each other, which confirms the relevance of using GBO for QA/QC of the results.

Gergeti Glacier: a − Schematic image of Ukandakhevi against the background of the Landsat 8 OLI TIRS sensor image of September 3, 2022. Green pins show the results obtained based on field expeditions; b − Graphs comparing the ground data of the SRS and field observations.

East Suatisi

Similarly, as in the previous cases calculations show that the analytical equation for the retreat of the East Suatisi glacier is:

Y=0.0874x²+15.354x-9.6214

The retreat patterns of Georgia’s major glaciers show regional differences. Glaciers in the Enguri Basin, such as Northern Liadeshti, Kvishi, and Adishi, have significantly accelerated their retreat since the early 2000s, coinciding with an increase in summer air temperatures of up to 0.6°C at the Mestia meteorological station. Glaciers in the Tergi Basin, including Gergeti and Eastern Suatisi, have experienced even stronger warming (up to 1.1°C at the Stepantsminda station), contributing to an even more significant increase in retreat dynamics.

These results highlight the importance of local climatic conditions, topographic parameters, and glacier morphology in influencing the speed and scale of glacier response to warming.

East Suatisi Glacier: a − Schematic image of retreat; b − Retreat graph.