Expansion of Glacial Lakes in Bhutan during 1990- 2009

Abstract

In recent decades, there are notable impacts of climate change on the glacial lakes in the Himalayan region. Therefore, the glacial lakes are expanding due to melting of the glaciers. The current study has been adapted to observe the changing pattern of glacial lakes during 1990 to 2009, which are located in the glacier mountain in Bhutan. The identification of the actual area of the lakes has been done using satellite imagery (Landsat TM and Landsat ETM+) by digitization after application of the correction methods (geometrical and radiometrical) on raw satellite images. The satellite images are utilized for the time periods of 1990, 2001, 2007 and 2009 for this study. The lake volume has been calculated using a glacial lake area and Digital Elevation Model (DEM). Finally, changes in the volume of lakes have been observed from 1990 to 2009. The highest increment of lake volume is found in the Luggye (45%) and Thorthormi (27%), while the lowest is observed in the Thorthormi-4 (1%). Overall, the highest expansion rate of glacial lakes is found in the Thorthormi-1 and Luggye around 0.036 km2/year and the smallest were Thorthormi-2 and Thorthormi-3 around 0.005 km2/year respectively. Higher extent (area and volume) of glacial lakes should be taken care to avoid the damage due to potential bursting.