Semi-automated mapping of glacial lakes – a study in Sikkim Himalayas, India

Abstract

In the Himalayas, rising number of glacial lakes with increase in area of existing lakes is a matter of serious concern and correct mapping is an important step towards regular monitoring of these glacial lakes. This study used Double Window Flexible Pace Search method to identify an optimal threshold of Normalized Difference Water Index value on multi-spectral Sentinel-2 image of 31^st October 2020. A threshold value of 0.30 is obtained that resulted in identification of 419 glacial lakes with an estimated total area of about 29.86 ± 6.85 km². The results are found to be in close agreement with previously published research article on Sikkim Himalayas and boundaries of classified lakes are validated by overlaying on high resolution PlanetScope dataset for the same date. Hence, this study presents an effective and simple way for mapping of glacial lakes that may further be extended for regular monitoring of glacial lakes in the region.

Keywords:

• Glacial lakes
• DFPS
• NDWI
• Sentinel-2A
• Sikkim Himalayas

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Supplementary material

The supplementary material has been attached with the article. The spatial location of glacial lakes and their extent are provided in Supplementary material 1. The detailed information of 419 glacial lakes mapped in this study are provided in Supplementary material 2. The shapefile for all mapped glacial lakes of Sikkim Himalayas are available from the corresponding author which will be uploaded to open repository after acceptance of article for publication.

Acknowledgements

Authors would like to acknowledge the comments from two anonymous reviewers, whose comments have helped us improve the quality of the manuscript. The authors would like to thank European Space Agency for providing Sentinel-2 images and Planet labs for providing high resolution PlanetScope dataset free of charge. The authors would also like to thank RGI Consortium (2017) for providing global inventory of glacier outlines free of cost.

Disclosure statement

No potential conflict of interest was reported by the author(s).