Modelling rock glacier ice content based on InSAR-derived velocity, Khumbu and Lhotse valleys, Nepal

IF 4.4 2区地球科学 Q1 GEOGRAPHY, PHYSICAL

Cryosphere Pub Date : 2023-06-08 DOI:10.5194/tc-17-2305-2023

Yan Hu, S. Harrison, Lin Liu, J. Wood

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引用次数: 1

Abstract

Abstract. Active rock glaciers are viscous flow features embodying ice-rich permafrost and other ice masses. They contain significant amounts of ground ice and serve as potential freshwater reservoirs as mountain glaciers melt in response to climate warming. However, current knowledge about ice content in rock glaciers has been acquired mainly from in situ investigations in limited study areas, which hinders a comprehensive understanding of ice storage in rock glaciers situated in remote mountains over local to regional scales. This study proposes a novel approach for assessing the hydrological value of rock glaciers in a more quantitative way and presents exploratory results focusing on a small region. We develop an empirical rheological model to infer ice content of rock glaciers using readily available input data, including rock glacier planar shape, surface slope angle, active layer thickness, and surface velocity. The model is calibrated and validated using observational data from the Chilean Andes and the Swiss Alps. We apply the model to five rock glaciers in the Khumbu and Lhotse valleys, northeastern Nepal. The velocity constraints applied to the model are derived from interferometric synthetic aperture radar (InSAR) measurements. The volume of rock glacier is estimated based on an existing scaling approach. The inferred volumetric ice fraction in the Khumbu and Lhotse valleys ranges from 70 ± 8 % to 74 ± 8 %, and the water volume equivalents lie between 1.4 ± 0.2 and 5.9±0.6×106 m3 for the coherently moving parts of individual rock glaciers. Due to the accessibility of the model inputs, our approach is applicable to permafrost regions where observational data are lacking, which is valuable for estimating the water storage potential of rock glaciers in remote areas.

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尼泊尔Khumbu和Lhotse山谷基于insar速度的岩石冰川冰含量模拟

摘要活动岩石冰川是一种粘性流动特征，包含了富含冰的永久冻土和其他冰块。它们含有大量的地下冰，当山区冰川因气候变暖而融化时，它们可以作为潜在的淡水水库。然而，目前关于岩石冰川冰含量的知识主要来自有限研究区域的实地调查，这阻碍了对偏远山区岩石冰川冰储量的全面了解。本研究提出了一种更定量地评估岩石冰川水文价值的新方法，并提出了侧重于小区域的探索性结果。我们开发了一个经验流变模型，利用现成的输入数据来推断岩石冰川的冰含量，包括岩石冰川的平面形状、表面坡度角、活动层厚度和表面速度。该模型使用智利安第斯山脉和瑞士阿尔卑斯山的观测数据进行校准和验证。我们将该模型应用于尼泊尔东北部昆布和洛子山谷的五座岩石冰川。应用于模型的速度约束来自干涉合成孔径雷达(InSAR)测量。岩石冰川体积的估算是基于现有的标度方法。在昆布和洛则山谷推断的体积冰分数在70±8% ~ 74±8%之间，而在单个岩石冰川的相干运动部分，水当量在1.4±0.2 ~ 5.9±0.6×106 m3之间。由于模型输入的可及性，我们的方法适用于缺乏观测数据的冻土地区，这对偏远地区岩石冰川的储水潜力预测有价值。

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来源期刊

Cryosphere GEOGRAPHY, PHYSICAL-GEOSCIENCES, MULTIDISCIPLINARY

CiteScore

8.70

自引率

17.30%

发文量

240

审稿时长

4-8 weeks

期刊介绍： The Cryosphere (TC) is a not-for-profit international scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on all aspects of frozen water and ground on Earth and on other planetary bodies. The main subject areas are the following: ice sheets and glaciers; planetary ice bodies; permafrost and seasonally frozen ground; seasonal snow cover; sea ice; river and lake ice; remote sensing, numerical modelling, in situ and laboratory studies of the above and including studies of the interaction of the cryosphere with the rest of the climate system.