Marine Geophysics and Hydroacoustics

Hydroacoustic mapping of Lake Sary-Chelek, Kyrgyzstan

Summary

Lake Sary-Chelek is a small lake in Western Kyrgyzstan, within the Tien Shan Mountain range at an altitude of about 1880m above sea level (Figure). It covers an area of ~5 km², with 6.5 km length and up to 2 km long. Water depth reaches up to 220 m in the center of Lake Sary-Chelek. The lake formed by river damming during a chatastrophic rockslide, which originated from a 2700 m high mountain chain southeast of the lake (Strom and Korup, 2006; Strom 2010). The rockslide has been More estimated to be older than at least 7000 years based on a sediment core from the small Lake Bakaly, located on top of the rockslide deposits (Beer et al., 2008). A major right-lateral Talas-fergana strike slip fault zone is located only 20 km northeast of Sary-Chelek (Strom and Korup, 2006).

overview

Figure 1: Topographic map and political outline of Kyrgyzstan in Central Asia.

The entire area is prone to landsliding and rockfalls, especially in Spring when the snow on the surrounding mountains is melting. Lauterbach et al. 2019 investigated the potential of Lake Sary-Chelek as a natural archive for regional earthquake activity. Cores have a uniform sediment succession across most of the lake basin with subrecent varved sediments overlying large-scale event deposits (Lauterbach et al. 2019). Large-scale turbidites in the sediment cores below varved sediments are most likely related to mass-transport events representing the subaquatic continuation of landslides/rockfalls or slope failures caused by a common and simultaneous trigger (Lauterbach et al. 2019).

innomar

Figure 2: View from the rubber boat through the Innomar transducer holder to the steep slopes of Sary-Chelek.

In September 2019 a field campaign using an Innomar SES Light 2000 system was carried out in order to evaluate the upper most sediments in Lake Sary-Chelek. The campaign is part of the PALESCA project funded by the BMBF at GFZ Potsdam initiated by Jens Mingram. We were very lucky with the weather and could use 3 full days of surveying on the lake (Figure 1, inlet). Now a dense grid of high resolution sediment echosounder data is available that will be analysised by a PhD student Kati Langenwalter at University Potsdam. Unfortunately the penetration was very limited due to the high topographic relief, steep slopes and most likely mass transport deposits with large size boulders. Nevertheless it will be possible to extract a first bathymetric map of Lake Sary-Chelek.

References

Beer, R., F. Kaiser, K. Schmidt, B. Ammann, G. Carraro, E. Grisa and W. Tinner (2008). "Vegetation History of the Walnut Forests in Kyrgyzstan (Central Asia): Natural or Anthropogenic Origin?" Quaternary Science Reviews 27(5): 621-632.

Lauterbach, S., J. Mingram, G. Schettler and S. Orunbaev (2019). "Two Twentieth-Century Mlh = 7.5 Earthquakes Recorded in Annually Laminated Lake Sediments from Sary Chelek, Western Tian Shan, Kyrgyzstan." Quaternary Research: 1-16.

Strom, A. (2010). "Landslide Dams in Central Asia Region." Journal of the Japan Landslide Society 47(6): 309-324.

Strom, A. L. and O. Korup (2006). "Extremely Large Rockslides and Rock Avalanches in the Tien Shan Mountains, Kyrgyzstan." Landslides 3(2): 125-136.

 

Contact Person: Dr. Katja Lindhorst

Corporation partner: Dr. Jens Mingram, Katrin Langenwalter (GFZ Potsdam) and Dr. Stefan Lauterbach (Uni Kiel)