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引用本文:

DOI:

10.11834/jrs.20210205

收稿日期:

2020-06-14

修改日期:

2021-02-09

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基于NDWI-NDSI组合阈值法的布加岗日冰湖提取及其变化分析
闫斌, 贾洪果, 任文静, 吴仁哲, 黄心茹
西南交通大学
摘要:

自20世纪90年代以来,中国冰川在全球升温影响下处于全面加速退缩的态势。长时序的冰湖变化既能反映冰川演变过程,也可为冰湖灾害研究提供重要依据。本文提出一种基于NDWI-NDSI组合法提取冰湖的改进方法,有效增加了阈值分割法提取冰湖的适用范围,使冰湖的错分现象得到极大改善;并以1988-2018年共16景landsat影像为数据源,成功对布加岗日冰川的冰湖面积实施提取并对其进行统计分析和时序研究。进而发现,该冰川出现冰湖数目增多(2个)、面积增大(约2.4642 km2)的现象,表明其在近30年间消融过快、退缩严重,并阐明温度变化为导致这一现象的主要因素,同时指出由冰川融水导致的部分冰湖诱发洪水、泥石流等次生灾害的可能性也极具增高。

Glacier lake extraction and its variation analysis of the Bujiagangri based on NDWI-NDSI combination threshold method
Abstract:

Glacier is a precious solid freshwater resource for humans. It has been changing dynamically due to the influence of climate. Glaciers not only play a role in regulating rivers, but also may cause a series of serious geological disasters in the process of evolution. Potential unsafe factors give humans social life poses a great threat. Since the 1990s, China’s glaciers have been in a trend of accelerating retreat under the influence of global warming. The rapid melting of glaciers will change the size of the surrounding ice lakes and form new ice lakes. An ice lake that develops to a certain extent will cause glacial lake disasters, and the geological disasters caused by glacial lake outburst have the characteristics of suddenness, great destructiveness, short duration, and wide spread. How to monitor glacial lake disaster and prevent it is an important task in glacier research. This paper takes the ice lake of the Bujiagangri Glacier located in the eastern section of Tanggula in southeastern Tibet as the research object, and takes the area of the ice lake as a measurement index. Based on these, an improved method for extracting ice lakes based on the NDWI-NDSI combined method is proposed. Then the area of the ice lake extracted by this method was compared and verified with the visual interpretation results. The experiment found that the method effectively increased the scope of application of the threshold segmentation method to extract the ice lake around the glacier, and the misclassification phenomenon in the extraction process of the ice lake was greatly improved. At the same time, 16 Landsat images covering the study area from 1988 to 2018 were used as the data source, and the combined method proposed in this paper was used to successfully extract the area of the ice lake of the Bujiagangri Glacier, and then statistics and time series research on them were carried out respectively. It was further discovered that during the evolution of the glacier, the number of ice lakes increased by 2 and the area expanded by about 2.4642 km2. Although the changes in the area of ice lakes cannot accurately reflect the ablation of the glacier and the amount of lake water changes, the results can still indicate that the glacier has melted too fast and retreated severely in the past 30 years, and the huge changes in the number and area of ice lakes have undoubtedly aroused people"s awareness of glacial lake disasters. In addition, this paper combines the relationship between the change in the area of ice lakes in the study area and the average annual temperature in the area to clarify that climate change is the main factor leading to this phenomenon. The increase in melting water from the Bujiagangri Glacier has also increased the possibility of secondary disasters such as floods and mudslides in some ice lake areas. This provides a basis for decision-making by relevant disaster prevention departments.

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