Contribution of ground ice melting to the expansion of Selin Co (lake) on the Tibetan Plateau

Abstract

Abstract. Selin Co, located within permafrost regions surrounded by glaciers, has exhibited the greatest increase in water storage among all the lakes on the Tibetan Plateau over the last 50 years. Most of the increased lake water volume has been attributed to increased precipitation and the accelerated melting of glacier ice, but these processes are still not sufficient to close the water budget with the expansion of Selin Co. Ground ice meltwater released by thawing permafrost due to continuous climate warming over the past several decades is regarded as another source of lake expansion. This study presents the first attempt to quantify the water contribution of ground ice melting to the expansion of Selin Co by evaluating the ground surface deformation. We monitored the spatial distribution of surface deformation in the Selin Co basin using the small baseline subset (SBAS) interferometric synthetic aperture radar (InSAR) technique and compared the results with the findings of field surveys. Then, the ground ice meltwater volume in the watershed was calculated based on the cumulated settlement. Finally, this volume was compared with the lake volume change during the same period, and the contribution ratio was derived. SBAS-InSAR monitoring during 2017–2020 illustrated widespread and large subsidence in the upstream section of the Zhajiazangbu subbasin, where widespread continuous permafrost is present. The terrain subsidence rate was normally between 5 and 20 mm a−1, indicating rapid ground ice loss in the region. The ground ice meltwater was released at a rate of ∼57×106 m3 a−1, and the rate of increase in lake water storage was ∼485×106 m3 a−1 during the same period, with ground ice meltwater contributing ∼12 % of the lake volume increase. This study contributes to explaining the rapid expansion of Selin Co and equilibrating the water balance at the watershed scale. More importantly, the proposed method can be extended to other watersheds underlain by permafrost and help in understanding the hydrological changes in these watersheds.

Quantification of Water Released by Thawing Permafrost in the Source Region of the Yangtze River on the Tibetan Plateau by InSAR Monitoring

“…We assume that the long-term subsidence is equivalent to the thickness of excess ground ice released from the original ground material. The released ground ice meltwater can be calculated via the following conversion of Equation 3 (Wang et al, 2022b).…”

“…SBAS‐InSAR utilizes multi‐master‐image InSAR pairs of small temporal‐spatial baselines to reduce the effects of decorrelation and is suitable for permafrost environments that undergo severe temporal decorrelation. Several studies have applied Sentinel‐1 data SBAS‐InSAR in monitoring deformation over permafrost terrain on the Tibetan Plateau (J. Chen et al., 2022; Daout et al., 2020; Daout et al., 2017; Lu et al., 2020; Reinosch et al., 2020; Wang et al., 2022a, 2022b, 2022; X. Zhang et al., 2019). According to research, the seasonal deformation over the Tibetan plateau is normally less than 50 mm, and thaw subsidence rates are normally between 5 and 20 mm/a, with certain ice‐rich permafrost regions having subsidence rates higher than 30 mm/year (J. Chen et al., 2022; Wang et al., 2022a).…”

“…Several studies have applied Sentinel-1 data SBAS-InSAR in monitoring deformation over permafrost terrain on the Tibetan Plateau (J. Chen et al, 2022;Daout et al, 2020;Daout et al, 2017;Lu et al, 2020;Reinosch et al, 2020;Wang et al, 2022aWang et al, , 2022bWang et al, , 2022. According to research, the seasonal deformation over the Tibetan plateau is normally less than 50 mm, and thaw subsidence rates are normally between 5 and 20 mm/a, with certain ice-rich permafrost regions having subsidence rates higher than 30 mm/year (J.…”

Dynamic Monitoring and Ecological Risk Analysis of Lake Inundation Areas in Tibetan Plateau

“…In recent years, the results of dynamic monitoring of lakes by many scholars have shown that climate change on the Tibetan Plateau has led to massive melting of glaciers, sufficient precipitation and surface runoff replenishment and other comprehensive factors, resulting in lake expansion and lake inundation areas [66]. Most scholars discuss the impact of the expansion of a single lake, and there are few studies on the lake inundation area of the Tibetan Plateau [14,15].…”

“…Cheng et al [13] evaluated the impact of the rapid expansion of Lake Angzi Co on adjacent villages. Chen and Wang et al [14,15] have shown that the level of the Selin Co Lake has been rising in recent years, leading to the inundation of surrounding high-quality grasslands, and the decline of animal husbandry has had a serious impact on local herdsmen. Although Liu and Wu et al [16,17] have recognized that inundation is an important factor affecting the landscape changes around the lake, there is still a lack of systematic and quantitative research on how the inundation process of different characteristics affects the landscape changes in the inundated area.…”