Abstract:
Glacial lake outburst flood (GLOF) is created when water dammed by a
glacier or a moraine is released. Some of the glacial lakes are unstable and most of
them are potentially susceptible to sudden discharge of large volumes of water and
debris which causes floods downstream i.e., GLOF. Many glacial lakes are known to
have formed in the Himalaya in the last half century, and a number of GLOF events
have been reported in the region in the last few decades. Due to extreme hazard
potential of GLOF events, it is necessary to take into account GLOF while planning,
designing and constructing any infrastructure, especially water resources projects, as
they are located on the path of glacial lake outburst flood wave and would be the
prime target in case of GLOF. GLOF modeling may be carried out by either scaled
physical hydraulic models or mathematical simulation using computer. A modern
tool to deal with this problem is the mathematical model, which is most cost effective
and reasonably solves the governing flow equations of continuity and momentum
by computer simulation. Mathematical modeling of dam breach floods can be
carried out by either one dimensional analysis or two dimensional analysis. In one
dimensional analysis, the information about the magnitude of flood, i.e., discharge
and water levels, variation of these with time and velocity of flow through breach
can be obtained in the direction of flow. In the case of two dimensional analyses,
the additional information about the inundated area, variation of surface elevation
and velocities in two dimensions can also be assessed. In the present paper, methodology
for simulation of glacier lake outburst floods has been discussed. Further,
the discussed methodology has been demonstrated in Dhauliganga basin located in
Northwestern Himalayan region. For the present case, MIKE-11 model of Danish
Hydraulic Institute has been selected in this study because of its modeling accuracy
for the slopes steeper than 0.01 and wide acceptability in more than 40 countries.
