<p><strong>Abstract.</strong> Present study is based on the change in surface area of the glaciers in downstream area of Dhauliganga basin, Pithoragarh district, Uttarakhand. For this study, Survey of India toposheets (surveyed in 1963) have been used for preparation of initial boundary of glaciers. Total 11 glaciers have been selected for the study in downstream valley. RGI (Randolph Glacier Inventory) data version 60. (15_RGI 60.SouthAsiaEast) from GLIMS, released July 28 2017, used for measuring temporal change in surface area. Landsat 8 OLI/TIRS image of 06 November 2016 has used to measure present area of glaciers. ASTER GDEM was used for automatic extraction of basin boundary by hydro-processing methods. Glacier boundaries were manually digitised from the Landsat image for better accuracy. The total glacier area was 69.35<span class="thinspace"></span>km<sup>2</sup> (1963), 48.10<span class="thinspace"></span>km<sup>2</sup> (2001) and 34.35 (2016) as determined from SOI toposheet, GLIMS and the Landsat image of 2016 respectively. Total vacated area by the retreat and melting of glaciers from 1963 to 2016 is 35<span class="thinspace"></span>km<sup>2</sup>, which accounts to a total loss of 50<span class="thinspace"></span>% from the total glaciated area. Google Earth imagery was also considered for marking the actual position of glacier outlines. Ice walls in topographic maps are also considered as the part of glacier but in present satellite image they are free from ice.</p>
The glacier database provides an opportunity to track its dynamics and address issues linked with water resources, hazards and sustainability. To better understand the dynamics of Eastern Dhauliganga basin, we mapped the clean and debris‐covered glaciers by using satellite images from Landsat‐series and Sentinel 2. The band‐ratio based methods—NDSI (Normalised Difference Snow Index) and NDVI (Normalised Difference Vegetation Index) were used to map the clean ice glaciers. The debris‐covered glaciers were delineated using topographic parameters and thermal band of Landsat TM. The glacier extent and length change were monitored for 25 glaciers in the basin, of which 13 are clean ice and 12 are debris‐covered glaciers. During the time period from 1994 to 2018, higher area loss was observed for clean ice glaciers (±20.6%) compared with debris‐covered glaciers (±10.9%). The clean‐ice glaciers retreated at a rate of 4.8–33.7 m/year, whereas debris‐covered glaciers retreated at a rate of 2.9–28.8 m/year during 1994–2018.
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