So, thoughts on mass wasting in Bangladesh:
Bangladesh, as already stated, is located in a delta and
situated at the base of a valley. This valley was actually formed by mass
wasting caused by landslides in the Himalayan range. Bangladesh is accruing
sediment as it washes down from the surrounding high elevations and it is
thereby gaining land mass but it is simultaneously losing sediment as the river
dumps it into the bay (as active deltas are wont to do). It receives heavy rainfall seasonally which
means that much of the region for a percentage of the year is saturated. The
areas surround Bangladesh suffer from landslides due to mass wasting especially
those countries such as Nepal, Pakistan, Bhutan and India- all of which are
located near large mountain ranges and all of which also experience seasonal flooding.
The few articles I was able to scrounge up regarding Bangladesh stated that not
enough data has been collected to engage in a serious scientific debate of how
large a role mass wasting plays in the country’s overall geological state. However,
there are papers and articles published on the subject, they usually squeeze
Bangladesh in an afterthought sort of fashion. So I went back to the maps of Bangladesh to
examine the elevation of areas which received the heaviest rainfall. The
steepest of the river banks are the Chittagong and Padma. It is important to
recall that many areas of Bangladesh are also severely arid (in fact tornadoes
are another one of the many natural disasters Bangladesh is at risk of). I
think that if the Chittagong Hills were hit with enough rain to get saturated
but not enough to wash all the plant life holding the soil together away that
those hills could continue to hold the moisture until the ground became to
saturated and heavy to resist the pull of gravity- thus some form of
mass-wasting. I do not think the landslides caused by mass wasting in
Bangladesh would cause the same amount
or even categorization of damage as I does in the surrounding countries (Nepal
suffers deadly mass wasting landslides during every monsoon season). I think if
Bangladesh did sustain the same kind of damage from mass wasting, the data
would be obvious. However, perhaps the monsoons wash away the soil to the
alluvial plain before it can become saturated enough to trigger mass wasting in
any other form than your garden variety torrential flooding.
The plan that Bangladesh has mapped out for mitigating calamitous
mass wasting is similar to that which they drew up for the rest of their
natural disasters. They will hopefully be able to communicate which areas should
evacuate and what, if anything can be done. There are satellites in place to
catch warning signs and evidence of mass wasting as it occurs over time in
Bangladesh and hopefully that information will reach the people fast enough for
them to move out of the way of a mass wasting event.
This is one of my favorite aspects of Bangladesh in regards
to natural disaster/ catastrophe: Bangladesh is at high risk of all manner of
natural disasters and their infrastructure as it stands will surely be unable
to withstand a disaster. It seems to be on the brink of all kinds of natural
disasters but it always either just misses the worst of the occurrence as with
the 2004 tsunami or it is as if the earth just keeps putting off its doomsday
as with the potential seismic activity and mass wasting.
Interesting that Bangladesh is formed around an existing example of mass wasting. I always picture events of mass wasting suffering impact from falling off of cliffs and mountains, rather than the already existing debris that fell long ago. The impact of events on fragile valleys is a unique dynamic. Sad to see the infrastructure is struggling to cover all risks.
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