Abstract:
Glacial hazards relate to hazards associated with glaciers and glacial lakes in
high mountain areas and their impacts downstream. The climatic change/variability in
recent decades has made considerable impacts on the glacier life cycle in the Himalayan
region. As a result, many big glaciers melted, forming a large number of glacial lakes. Due
to an increase in the rate at which ice and snow melted, the accumulation of water in these
lakes started increasing. Sudden discharge of large volumes of water with debris from these
lakes potentially causes glacial lake outburst floods (GLOFs) in valleys downstream.
Outbursts from glacier lakes have repeatedly caused the loss of human lives as well as
severe damage to local infrastructure. Monitoring of the glacial lakes and extent of GLOF
impact along the downstream can be made quickly and precisely using remote sensing
technique. A number of hydroelectric 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. The
present study deals with the estimation of GLOF for a river basin located in the Garwhal
Himalaya, India. IRS LISSIII data of the years 2004, 2006 and 2008 have been used for
glacial lake mapping, and a total of 91 lakes have been found in the year 2008, and out of
these, 45 lakes are having area more than 0.01 km2. All the lakes have been investigated
for vulnerability for potential bursting, and it was found that no lake is vulnerable from
GLOF point of view. The area of biggest lake is 0.193, 0.199 and 0.203 km2 in the years
2004, 2006 and 2008, respectively. Although no lake is potentially hazardous, GLOF study
has been carried out for the biggest lake using MIKE 11 software. A flood of 100-year
return period has been considered in addition to GLOF. The flood peak at catchment outlet
comes out to be 993.74, 1,184.0 and 1,295.58 cumec due to GLOF; 3,274.74, 3,465.0 and
3,576.58 cumec due to GLOF; and 100-year return flood together considering breach width
of 40, 60 and 80 m, respectively.
