Spatio-temporal and surface elevation change assessment of glaciers of Sikkim Himalaya (India) across different size classes using geospatial techniques

An assessment of the influence and significance of different topographic and morphometric parameters of glacier catchments such as size, average slope, median elevation, and aspect upon the spatio-temporally changing characteristics of glaciers belonging to different size classes in Tista river basin of Sikkim Himalaya has been performed. The reference years of 2000 and 2018 were considered and different morphometric techniques showed recessive nature and shape change of the observed main glaciers along with some of the tributary glaciers. Pearson’s correlation coefficient and Student’s t test were applied to measure the correlation and statistical significance of used parameters to understand the varying morphometric and topographic conditions of the glaciers. LANDSAT TM (thematic mapper), LANDSAT 7 ETM + (enhanced thematic mapper), and LANDSAT 8 (OLI) (operational land imager) imageries and shuttle radar topographic mission (SRTM) digital elevation model (DEM) and different automated and semi-automated techniques indicated overall loss of 19.78% over the years 2000 to 2018 of the glaciated area investigated and such decrease in respective years of reference was 2.06% for the year 2000 and 1.65% for the year 2018, respectively, of the total geographic area of Sikkim. TanDem-X DEM (90 m) was useful in inferring glacier surface elevation change.