Glacier branch lines and glacier ice thickness estimation for debris-covered glaciers in the Central Tien Shan

Pieczonka, Tino; Bolch, Tobias; Kröhnert, M.; Peters, Juliane; Liu, Shiyin

doi:10.1017/jog.2018.75

Cited by 21 publications

(26 citation statements)

References 59 publications

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“…Future lake developments were estimated using GlabTop (Linsbauer and others, 2016). The bed overdeepenings at slow flowing termini could be slightly overestimated by GlabTop as the flow of glaciers is not considered in this model (Pieczonka and others, 2018). Uncertainties in the overdeepenings can result from the resolution and offset between SRTM DTM and the glacier outlines.…”

Section: Discussionmentioning

confidence: 99%

Glacial lake evolution and glacier–lake interactions in the Poiqu River basin, central Himalaya, 1964–2017

et al. 2019

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Despite previous studies, glacier–lake interactions and future lake development in the Poiqu River basin, central Himalaya, are still not well understood. We mapped glacial lakes, glaciers, their frontal positions and ice flow from optical remote sensing data, and calculated glacier surface elevation change from digital terrain models. During 1964–2017, the total glacial-lake area increased by ~110%. Glaciers retreated with an average rate of ~1.4 km2 a−1 between 1975 and 2015. Based on rapid area expansion (>150%), and information from previous studies, eight lakes were considered to be potentially dangerous glacial lakes. Corresponding lake-terminating glaciers showed an overall retreat of 6.0 ± 1.4 to 26.6 ± 1.1 m a−1 and accompanying lake expansion. The regional mean glacier elevation change was −0.39 ± 0.13 m a−1 while the glaciers associated with the eight potentially dangerous lakes lowered by −0.71 ± 0.05 m a−1 from 1974 to 2017. The mean ice flow speed of these glaciers was ~10 m a−1 from 2013 to 2017; about double the mean for the entire study area. Analysis of these data along with climate observations suggests that ice melting and calving processes play the dominant role in driving lake enlargement. Modelling of future lake development shows where new lakes might emerge and existing lakes could expand with projected glacial recession.

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Section: Discussionmentioning

confidence: 99%

Glacial lake evolution and glacier–lake interactions in the Poiqu River basin, central Himalaya, 1964–2017

et al. 2019

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“…In this model, the basal shear stress along the central flowlines is set equal to an average yield stress ( τ y ) which is calibrated with the measured ice thicknesses based on the following relations:with α the local surface slope and ρ the average ice density (900 kg m −3 ). Following Li and others (2012) and Pieczonka and others (2018), a shape factor ( f ) is introduced to account for the drag by the valley walls. For simplicity, we assume a constant of 0.8, similar to the value used for the consensus estimate (Farinotti and others, 2019) and in the parametrization scheme of Haeberli and Hoelzle (1995).…”

Section: Ice Thickness Modelling In Unmeasured Areasmentioning

confidence: 99%

“…Previous studies showed that Eqn (5) tends to overestimate the ice thickness in very flat regions (small slope). Therefore, we implemented a minimum slope of 5% (Farinotti and others, 2009, 2017; Carrivick and others, 2016; Pieczonka and others, 2018). However, we do not observe slopes smaller than 5% at the reconstruction points.…”

Section: Ice Thickness Modelling In Unmeasured Areasmentioning

confidence: 99%

“…Moreover, differences between the individual reconstruction models are unsatisfying as a result of the scarcity of in situ measurements used for calibrating these models (Sorg and others, 2012; Unger-Shayesteh and others, 2013; Kutuzov and others, 2018; Farinotti and others, 2019) and additional detailed ice thickness reconstructions based on measurements are needed. To date, the ice thickness of only a handful of glaciers in the Tien Shan is known from geophysical observations using a radio-echo sounding (RES) system, and most of them are located in the eastern areas of the Tien Shan (Hagg and others, 2013; Zhen and others, 2013; Petrakov and others, 2014; Wang and others, 2014; Nosenko and others, 2016; Pieczonka and others, 2018).…”

Section: Introductionmentioning

confidence: 99%

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Measuring and inferring the ice thickness distribution of four glaciers in the Tien Shan, Kyrgyzstan

et al. 2020

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Glaciers in the Tien Shan mountains contribute considerably to the fresh water used for irrigation, households and energy supply in the dry lowland areas of Kyrgyzstan and its neighbouring countries. To date, reconstructions of the current ice volume and ice thickness distribution remain scarce, and accurate data are largely lacking at the local scale. Here, we present a detailed ice thickness distribution of Ashu-Tor, Bordu, Golubin and Kara-Batkak glaciers derived from radio-echo sounding measurements and modelling. All the ice thickness measurements are used to calibrate three individual models to estimate the ice thickness in inaccessible areas. A cross-validation between modelled and measured ice thickness for a subset of the data is performed to attribute a weight to every model and to assemble a final composite ice thickness distribution for every glacier. Results reveal the thickest ice on Ashu-Tor glacier with values up to 201 ± 12 m. The ice thickness measurements and distributions are also compared with estimates composed without the use of in situ data. These estimates approach the total ice volume well, but local ice thicknesses vary substantially.

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“…a −1 during 1999−1 during -2007−1 during (Shangguan et al, 2015, with surface-flow velocities in its upper part being faster than those on its lower part (Nobakht et al, 2014;Shangguan et al, 2015). The estimated maximum thickness is 380 m, and the mean thickness of its debris-covered part is 136 m (Pieczonka et al, 2018). Many supraglacial lakes have developed on its debris-covered area with an annual seasonal drainage cycle (Narama et al, 2017).…”

Section: Study Areamentioning

confidence: 99%

Daily water-level variations of supraglacial lakes in the southern Inylchek Glacier, Central Asia

Sakurai

Narama

Daiyrov

et al. 2020

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Abstract. To better understand the storage in and drainage through supraglacial lakes and englacial conduits, we investigated the daily water-level variations of supraglacial lakes on the southern Inylchek Glacier in Kyrgyzstan. To examine these variations, we used daily aerial digital images over three years (22 July–15 August 2017, 8–29 July 2018, and 12–19 July 2019) from an unmanned aerial vehicle (UAV) that were converted to digital surface models (DSMs) and ortho-images. Our main results are as follows. 1) When one lake drained, the water levels of other lakes might simultaneously increase, indicating that drainage water is shared with several lakes through a main englacial conduit. In one drainage event, a branch englacial conduit clearly connected to a main englacial conduit. 2) Sometimes, several lakes discharged simultaneously, indicating that several lakes had connected to a main englacial conduit that had opened. Such a case can cause larger-scale drainage than that from the opening of a branch englacial conduit. 3) Several lakes discharged twice in the same year, each time through a different conduit, indicating that the main englacial conduit can be abandoned and reused. 4) In some lakes, the water level gradually increased with nearly the same increase rate just before drainage. Such an increase may be an indicator of imminent lake drainage.

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Glacier branch lines and glacier ice thickness estimation for debris-covered glaciers in the Central Tien Shan

Cited by 21 publications

References 59 publications

Glacial lake evolution and glacier–lake interactions in the Poiqu River basin, central Himalaya, 1964–2017

Glacial lake evolution and glacier–lake interactions in the Poiqu River basin, central Himalaya, 1964–2017

Measuring and inferring the ice thickness distribution of four glaciers in the Tien Shan, Kyrgyzstan

Daily water-level variations of supraglacial lakes in the southern Inylchek Glacier, Central Asia

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