5:15 PM - 7:15 PM
[ACC32-P05] The effect of meltwater on the formation of short-lived lakes in the northern Tien Shan
Keywords:Short-lived glacial lake , Glacial Lake Outburst Flood, Glacier melt, Tien Shan
In the Tien Shan Mountains and Teskei Mountains located in the Kyrgyz Republic in Central Asia (Daiyrov et al., 2020, 2022), many small glacial lakes have been experiencing frequent floods since 2000, causing extensive damage in the lower reaches of these lakes. In July 2008, a flood in the West Dzundan glacial lake in the Teskay Mountains killed three people and devastated infrastructure such as roads and bridges, as well as agricultural land (Narama et al., 2010). The lakes that cause glacial lake outburst floods are called “short-lived glacial lakes,” which emerge and flood in just a few months to a few years. In this region, debris landforms (glacier-moraine complex) containing buried ice are formed in front of glacial lakes (Shatravin, 2007), and drainage of glacial lakes takes place through ice tunnels developed inside these landforms. When these tunnels are blocked by freezing or landslides in winter, meltwater from spring to summer is dammed, forming short-lived glacial lakes. In this study, we focused on short-lived glacial lakes that appear in July and August every year, and investigated the mechanism of glacial lake formation based on observation data.
The study area is the Kolmudu Glacial Lake in the Teskei Mountains located in the Kyrgyz Republic in Central Asia. The volume of the glacial lake was estimated daily using the DSM of the lake basin generated from UAV aerial imagery and the area change of the glacial lake obtained from satellite imagery PlanetScope (3m resolution). The Degree Day method was used to calculate the amount of melting (inflow into the lake) of glaciers bordering the glacial lake. The temperature data used were observed at hourly intervals at the terminus of the glacier. In order to calculate the Degree Day Factor, we also measured the melting depth.
The results of the variation of glacier melt volume and glacial lake volume (storage volume) in 2023 show that the melt volume increases from the beginning of June, when the temperature is well above 0°C. After the glacial lake expands, the melt volume decreases and the glacial lake volume increases. After the glacial lake expanded, the volume of the glacial lake began to decrease from August 8, and the glacial lake completely disappeared by the end of August. The formation and disappearance of the glacial lake lasted about three weeks each. In all years except 2020, when the lakes appeared, the lakes appeared from July to mid-August, but the maximum volume of the lakes varied from year to year.
We examined the variation in the amount of glacier melt (inflow to the lake), glacial lake storage volume, and discharge from the glacial lake, and confirmed that glacial lakes begin to form when the inflow exceeds the discharge. The glacial lake storage volume was determined using the discharge volume at the timing when the glacial lake continued to expand, and the results were inconsistent with the rapid glacial lake volume change in 2017. This suggests that the formation of glacial lakes may be related not only to increased glacial melt but also to decreased discharge due to tunnel closure.
The study area is the Kolmudu Glacial Lake in the Teskei Mountains located in the Kyrgyz Republic in Central Asia. The volume of the glacial lake was estimated daily using the DSM of the lake basin generated from UAV aerial imagery and the area change of the glacial lake obtained from satellite imagery PlanetScope (3m resolution). The Degree Day method was used to calculate the amount of melting (inflow into the lake) of glaciers bordering the glacial lake. The temperature data used were observed at hourly intervals at the terminus of the glacier. In order to calculate the Degree Day Factor, we also measured the melting depth.
The results of the variation of glacier melt volume and glacial lake volume (storage volume) in 2023 show that the melt volume increases from the beginning of June, when the temperature is well above 0°C. After the glacial lake expands, the melt volume decreases and the glacial lake volume increases. After the glacial lake expanded, the volume of the glacial lake began to decrease from August 8, and the glacial lake completely disappeared by the end of August. The formation and disappearance of the glacial lake lasted about three weeks each. In all years except 2020, when the lakes appeared, the lakes appeared from July to mid-August, but the maximum volume of the lakes varied from year to year.
We examined the variation in the amount of glacier melt (inflow to the lake), glacial lake storage volume, and discharge from the glacial lake, and confirmed that glacial lakes begin to form when the inflow exceeds the discharge. The glacial lake storage volume was determined using the discharge volume at the timing when the glacial lake continued to expand, and the results were inconsistent with the rapid glacial lake volume change in 2017. This suggests that the formation of glacial lakes may be related not only to increased glacial melt but also to decreased discharge due to tunnel closure.