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Bangladesh
is a target for natural disasters of all sorts including earthquakes, floods,
tropical storms, drought, subsidence, and monsoons. However, without contest,
those hazards which affect the drinking water supply of this country are the
most dangerous. As with many earth-related phenomenon, many of these disasters
are linked together as in a chain reaction.
I will review the disastrous effects of tropical storms and
drought-related disasters (which include subsidence and other ground water
issues).
A word about tropical storms:
The tropical storms which Bangladesh is subject to are classified as cyclones
(which is just another term for hurricane except that it is more commonly used
in the Asian Pacific.) Cyclones/ hurricanes are low pressure systems. At the
center on the cyclone spiral is the eye, which has the lowest pressure of the
cyclone. Tropical cyclones are warmer low pressure systems which result from passing
major thunderstorms. Tropical storms are definitely one of the main foci of the
natural disaster mitigation and relief efforts in Bangladesh. The death toll
during tropical such the cyclones which hit the coast on a fairly regular basis
is usually instantaneous and devastating. As explained in previous entries,
some of the most devastating cyclones to affect Bangladesh include the 1970
Bhola Cyclone which killed approximately 500,000 people, and the most recent
storm was the Cyclone Sidr which hit Bangladesh in 2007 killed approximately
2,000 people. These storms also cause extreme property damage, wipe out coastal
fisheries, cattle populations, deltaic crops, destroy the mangrove forest which
protects the western edge of the coast and they contribute to the heavy erosion
of the coastal sediment which then contributes to high salinity levels inland.
Some years, the coast of Bangladesh is hammered with multiple large-scale
cyclones (exp. In 1983, both in October
and November Bangladesh suffered from two separate cyclones). Approximately 90% of the human loss of life is
due to initial storm surge. Storm surge is the sudden wave of water which
occurs during a storm such as a hurricane, not to be confused with a tsunami or
rogue wave, it is more accurately described as an ocean based flash flood.
Surges can travel as far inland as 25 miles and they wipe out nearly everything
their path. Bangladesh experiences usually at least on cyclone per year and
although the cost of human life has decreased significantly since 1970, the coast
never really is allowed the opportunity to fully rebuild its infrastructure or
way of life.
However,
Bangladesh at least has designed mitigation plans specifically for Cyclones. Mitigation
for cyclones includes the construction of cyclone shelters and a coastal
warning system which makes it possible for people to leave their homes and
either simply move to higher ground, further inland or reach a designated
cyclone shelter, or simply the closest shelter to their current area. The
coastal areas need to have a strictly regimented cyclone mitigation plan
because the coastal population itself is high in number and also ill-organized
with a weak infrastructure. The combination of those two components makes
cyclones even more dangerous as when they do make land fall the area they
strike is filled with people who live in weak structures in close quarters
which can cause wide spread panic and miscommunication. The sheer population
density, as would be expected hikes up the death toll for those people who
remain simply on a statistical basis (the more people left on the coast, the
more people killed in the initial storm surge). Another cause of death is disease and injury
as well as loss of livelihood which occur as a direct result of these storms.
Furthermore, due to the damage cyclones cause to the sediment of the coast, potable
water becomes yet another issue as the delta and the shore erodes salt water
seeps into the coast line and moves north with each new surge making the soil
barren and the water undrinkable. These cyclones rip up the mangrove forests, contribute
to the disintegration of the coast islands (which also protect the central and
eastern edges of the coast from storms much like a barrier reef would
elsewhere).
The aforementioned
brings us to a second major ongoing geological disaster which is water. The
issue of water management, preservation and all issues regarding potable water
are the most prevalent and dangerous which Bangladesh faces. There are many
water-geological problems in Bangladesh; too many to cover in an entry such as
this. They are all inter-related and as each new issue comes up there is a sort
of domino effect as more and more systems are disturbed. The biggest problem
which Bangladesh faces is water availability. In the Northern areas of the
country, the ground water is heavily poisoned with arsenic which naturally occurs
in the soil. Furth south and especially close to the coast, the ground water
and surface water are becoming steadily more and more brackish as the ocean
infiltrates the delta, its watershed and seeps into the soil. The aforementioned
mangrove forest on the western coast can grow in somewhat brackish water but as
the salinity of the soil increases their root systems die. Sea level is also
rising (as it all over the world due to climate change). As sea level rises it
contributes to the seepage of salt into the coast and it has begun to flood
into the delta regions, giving it the same characteristics of a brackish estuary.
Also as sea level rises, it erodes the coastal sediment away and the mangroves with
weakened root systems do not have any solid ground to cling to so they wash
away with the soil. When the mangroves wash away part of the coastal defense
against storm surge is weakened which brings us all the way back to the dangers
of storm surge in general and not excluding the further salinization of the
soil inland.
Because
drinkable water is hard to come by in Bangladesh the country has attempted has
basically exhausted what little clean ground water by sucking the soil dry. The
dryer the soil gets, the more it subsides and. As subsidence worsens, the pores
where ground water would normally collect shrink, turning the layers beneath
the farmland areas into clay. This makes it hard to grow crops. Clay is not
porous enough to become an aquifer again so whenever the monsoons arrive (right
around the time the cyclones roll around) instead of some of the rain water
seeping back into the earth and replenishing the aquifers for potential
extraction later, it all runs off into the ocean again over a weakened and
eroded coast line, taking more sediment with it and exacerbating the problem
even further.
Obviously,
all of the above makes for a fairly constant disaster scenario. Unfortunately,
there is very little being done to mitigate the issue. I honestly am not sure
what Bangladesh could do to mitigate the water issues it faces short of
building a desalinization plant somewhere near the coast. However, such a plant
would be in danger of sustaining major damage every time monsoon/tropical storm
season came about in the fall. A desalinization plant would also disrupt the
local coastal processes, especially the shrimp farming industry as it would
suck up anything big enough to fit past its initial grate filter. Bangladesh is
fast becoming an inhospitable area especially in regards to water. I predict
that as they run out of water options, the people of Bangladesh will be forced
to relocate, potentially north or to either one of its neighboring countries,
India or Myanmar. Personally I would not build my house anywhere in Bangladesh, but if I had no other choice: I would build my house on high ground to avoid the coastal problems and near the border of India so I could immigrate quickly if necessary. Finally, I would build my house with a large, sturdy rain-water collection system so as to avoid the arsenic in the ground water. I would also have to have a decontamination unit of some kind in order to avoid getting sick via bacteria. Or perhaps I would just have to ignore my personal morals and make a big deal with Pepsi so that I could have crates of bottled water delivered via parachute every week.
