Detection and delineation of glacial lakes and identification of potentially dangerous lakes of Dhauliganga basin in the Himalaya by remote sensing techniques

Glaciers are retreating and thinning in the high altitude of the Himalayas due to global warming, causing into formation of numerous glacial lakes. It is necessary to monitor these glacial lakes consistently to save properties and lives downstream from probable disastrous glacial lake outburst flood. In this study, image processing software ArcGIS and ERDAS Imagine have been used to analyse multispectral image obtained by Earth resource satellite Landsat for delineating the glacial lakes with the help of image enhancement technique like NDWI. Landsat data since 1972 through 2013 have been used and maximum seven glacial lakes (L1-L7) have been detected and delineated in Dhauliganga catchment, they are situated above 4000 masl. The Glacial Lake L2 (Lat 30A degrees 26'45aEuro(3)E and Long 80A degrees 23'16aEuro(3)N) is the largest whose surface area was 132,300 m(2) in Sept 2009, and L6 (Lat 30A degrees 23'27aEuro(3)E and Long 80A degrees 31'52aEuro(3)N) is highly unstable with variation rate -55 to +145 % with increasing trend. Additionally, glacial lakes L2 (Lat 30A degrees 26'45aEuro(3)E and Long 80A degrees 23'16aEuro(3)N) and L6 (Lat 30A degrees 23'27aEuro(3)E and Long 80A degrees 31'52aEuro(3)N) have been identified as potentially hazardous. These lakes may probably burst; as a result, huge reserve of water and debris may be released all on a sudden. This may transform into hazardous flash flood in downstream causing loss of lives, as well as the destruction of houses, bridges, fields, forests, hydropower stations, roads, etc. It is to note that Dhauliganga river considered in this study is a tributary of Kaliganga river, and should not be confused with its namesake the Dhauliganga river, which is a tributary of Alaknanda river.