Abstract:
Glaciers have perennially been the source of fresh water for more than
1.3 billion of people in the Indian subcontinent. The climatic change and variability
in recent decades has made considerable impacts on the glacier lifecycle in the
Himalayan region. Warmer climates of the past have resulted in glacier retreat and
the formation of glacial lakes in many mountain ranges. The lakes, located at the
snout of the glacier, are mainly dammed by the lateral or end moraine, where there
is a high tendency of breaching. Sudden discharge of large volumes of water with
debris from these lakes potentially causes Glacial Lake Outburst Floods (GLOFs)
in valleys downstream. A number of hydroelectric (HE) projects in India are being
planned in the Himalayan regions. It has become necessary for the project planners
and designers to account for the GLOF also along with the design flood for
deciding the spillway capacity of projects located in similar hydro-meteorological
regions. In order to assess the possible hazards from such lakes it is therefore
essential to have a systematic inventory of all such lakes formed at the high
altitudes. The hazardous lakes, however, are situated in remote areas and are very
difficult to monitor through ground surveys due to rugged terrain and extreme
climatic conditions. Monitoring of the glacial lakes and extent of GLOF impact
along the downstream can be done quickly and precisely using time series satellite
images and aerial photographs. To identify the individual glaciers and glacial
lakes, different image enhancement techniques are useful. Besides making a temporal
inventory, a regular monitoring of these lakes is also required to assess the
change in their nature and aerial extent. In the present paper, identification of glacial
lakes has been carried out using IRS LISSIII data. Also criteria for identification
of potentially dangerous lake have been discussed.
