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Glacier inventories serve as critical baseline data for understanding the impacts of climate change on glaciers. The present study maps the outlines of glaciers in the Chandra-Bhaga Basin (western Himalaya) for the years 1993, 2000, 2010, and 2019 using Landsat Thematic Mapper (TM), Enhanced Thematic Mapper (ETM), and Operational Land Imager (OLI) datasets. A total of 251 glaciers, each having an area above 0.5 km2, were identified, which include 216 clean-ice and 35 debris-covered glaciers. Area changes are estimated for three periods: 1993–2000, 2000–2010, and 2010–2019. The total glacierized area was 996 ± 62 km2 in 1993, which decreased to 973 ± 70 km2 in 2019. The mean rate of glacier area loss was higher in the recent decade (2010–2019), at 0.036 km2, compared to previous decades (0.029 km2 in 2000–2010 and 0.025 km2 in 1993–2000). Supraglacial debris cover changes are also mapped over the period of 1993 and 2019. It is found that the supraglacial debris cover increased by 14.12 ± 2.54 km2 (15.2%) during 1993–2019. Extensive field surveys on Chhota Shigri, Panchi II, Patsio, Hamtah, Mulkila, and Yoche Lungpa glaciers were carried out to validate the glacier outlines and supraglacial debris cover estimated using satellite datasets. Controls of various morphological parameters on retreat were also analyzed. It is observed that small, clean ice, south oriented glaciers, and glaciers with proglacial lakes are losing area at faster rates than other glaciers in the basin. [ABSTRACT FROM AUTHOR]

Delineation of Glaciers is a challenging task in the Himalaya due to its complex topography, cloud cover, seasonal snow cover, hillshade, debris cover. Glacio-hydrological studies including mass balance, run-off, and dynamic modelling rely on the availability of consistent and reliable glacier inventory datasets. This article on data set presents a homogenous, multidecadal inventory of glaciers in the Chandra-Bhaga Basin (CB Basin), western Himalaya, for 1993, 2000, 2010, and 2019. Landsat Thematic Mapper (TM), Enhanced Thematic mapper (ETM+), and Operational Land Imager (OLI) imageries, with minimum snow and cloud cover have been used for enhanced accuracy and consistency. Uncertainty assessment for the generated glacier inventory was performed, following various approaches such as buffer method, standard error estimation, and manual digitisation error and the maximum uncertainty has been quantified. We have identified and manually mapped a total of 251 glaciers with an area > 0.5 km², and in order to minimise the uncertainty, field surveys were carried out on 6 glaciers in the basin. Out of these 251 glaciers, 217 are clean ice and 35 were debris-covered glaciers. The estimated total glacier area was 996 ± 62 km² in 1993 that decreased to 973 ± 70 km² in 2019. Apart from quantifying temporal changes in glacier area, this inventory further allows the estimation of supraglacial debris cover and glacier volume. The supraglacial debris cover area has increased by 14.1 ± 2.54 km² (15.2 %) during 1993-2019. Accuracy of the debris cover dataset estimated using ground surveys is 82 % with a kappa coefficient of 0.87. Moreover, a glacier ice volume dataset was also generated by incorporating the inventory into Glacier Bed Topography Version 2 (GlabTop2) model and shows a total of 112.5 ± 41 km³ of ice volume stored in the CB Basin glaciers. For accuracy assessment of the DEMs generated using ASTER Stereopairs images, DGPS surveys were carried out on (28 GCPs) and off (6 GCPs) the glaciers. Glacier volume uncertainty with respect to the generated DEMs and model bias is 5.3 km³ and 35.5 km³ respectively. Overestimation of glacier volume due to over deepening is estimated to be 1.2 km³. The impact of climate change on the Himalayan glaciers is a matter of serious concern and such holistic multitemporal inventory datasets can help quantify that impact with improved certainty. [ABSTRACT FROM AUTHOR]