Intensive field studies during the years 2010 to 2014 allowed developing the rules for the permafrost distribution in the Kyrgyz Tianshan. The results are published online in the dissertation "Glaciers and permafrost in Kyrgyzstan - distribution, recent dynamics, and relevance as water resource and hazard factor for the development of Central Asian semiarid regions" by Murataly Turganalievich Duishonakunov, currently at Kyrgyz National University of Kyrgyzstan, and CAIAG Bishkek. The project was financed by Volkswagenstiftung (LUCA project), supervised by Ryskul Usubaliev/Lorenz King and logistically supported by CAIAG Bishkek.
Studies for distribution and temperature of ground ice
For the current study we investigated frozen ground in the upstream Naryn catchments, between August 2010 and August 2013. We measured the near-surface ground temperature at 18 locations at different altitudes and slopes. The objectives of this study are to estimate the distribution of permafrost, and its active layer, and to discuss the permafrost environment in the upstream Naryn catchments. The general features of mountain permafrost such as permafrost distribution and temperatures, active layer thicknesses within the upstream Naryn catchments, Tian Shan Mountains are described. The area of permafrost studies in the Naryn basin is located within the two upstream river basins (Chon Naryn and Kichi Naryn). The mountain permafrost zone in our study area belongs to the Asian mountain permafrost area, the largest in the world.
In the field we used steel rods and a hammer to dig holes up to 1.5 m deep for our thermistor strings. Ground temperature measurements were carried out in 18 locations in our study area between altitudes 3007 and 4043 meters. These ground temperature measurements performed using wireless mini thermistor sensors (M-Log5W) and data sampling continues. They have a high memory capacity (2048 kB), low energy consumption and waterproof cover. The temperature sensor has a high resolution of 0.01 °C and an overall accuracy of ± 0.1 °C. This thermistor can work more than 5 years without changing batteries depending on temperature conditions of the ground. The temperature recording started in August 2010 at an hourly interval at all locations the observation period was up to end of August 2013.
The lower altitudinal limit of the sporadic permafrost in Naryn basin is as low as 2700 meters. We have data at our disposal on location of permafrost on northern slopes at altitudes between 3334 and 3756 meters (Akshyirak, Uchemchek and Sook mountain ranges), on southern slopes at altitudes between 3007 and 3875 meters (Terskey, Sook, Uchemchek, Jetim mountain ranges), on western slopes at altitudes of 3650 to 4043 meters (Akshyirak and Sook mountain ranges) and on eastern slopes at altitudes of 3781 to 3865 meters (Terskey and Sook mountain ranges). The sporadic permafrost area is increasing by the altitude; there are more and more such areas and the area of discontinuous permafrost starts somewhere near the hypsometric line of 3300 meters. Here the area with permafrost is larger than the non-permafrost area. Permafrost is wide-spread throughout, at altitudes above 3200-3400 meters we propose to regard the contour line of 3300 meters as the lower limit of discontinuous permafrost in the Upstream Naryn basin. Above 3600 m the continuous permafrost zone starts.
High mountain permafrost and periglacial landforms may contain large quantities of fresh water in the form of ice. Especially glacier moraines and rock glaciers have high ice content. Rock glaciers are ice-rich periglacial landforms, ice can occupy up to 80% of the volume.
Our data in the Kumtor catchment during 2001-2011 show (Figure 1) that the ten years average annual ground temperatures were between -0.2 °C (at the depth of 5 cm) and -1.3 °C (at the depth of 300 cm) warmer than the mean annual air temperature (-5.73 °C; MAAT). Annual average temperatures during the last ten years at the depth of 100, 150 and 300 cm never were above 0 °C. Other measurements in 18 locations during August 2010 and August 2013 show that the average annual ground temperatures at the depth of 10 cm ranged between +4.4 °C (south slope of Uchemchek mountain, 3007 m) and -4.3 °C (north slope of Sook mountain, 4043 m).
Figure 1: Average annual ground temperature variability at the depth of 5 cm, 10 cm, 20 cm, 50 cm, 100 cm, 150 cm and 300 cm, Tian Shan meteorological station, 3659 m a.s.l., 2001-2011). Source: processed from the Tian Than Meteo data.
The data in figure 1 show that average ground temperatures at similar depths are significantly below at Tian Shan Station. Large-amplitude temperature variations are observed at Tian Shan Station and other 17 locations.
The duration of the freezing period is increased with the depth of the active layer. The number of days which daily are crossing 0 °C in Tian Shan meteostation (3659 m) at the depth of 5 cm make up 197 days, at the depth of 50 cm 219 days, at 150 cm 271 days, and at 300 cm – 365 days (average for 2001-2011; Table 1).
Table 1: Number of days with daily crossing 0°C at a depth of 5, 10, 20, 50, 100, 150 and 300 cm in the Tian Shan meteorological station (3659 m a.s.l.) from 2001 to 2011.
Report prepared by Ryskul Usubaliev ( [email protected])