Today's Atlantis: the Thai Buddist temple Wat Khun Samut Trawat
My
last post was criticized about the doomsday prophecies I
made about the Fennoscandian area (I think dear Annie missed the
non-seriousness in my text, but heck, he/she got a point). The
mentioned process of land uplift takes a lot of time and
the dramatic geological change will not affect our way of
life in a long time. So I decided to write about a geological change
that does affect the way of life already today and dramatically in
the future. The research I write about is from a couple of
my colleagues working a lot with people from Thailand. They
are part of a research project called GEO2TECDI-2,
which uses GNSS, InSAR and tide gauges to see the movement of the
surface of Thailand with respect to the sea level.
When
you look at the topography of Thailand, you will notice that the
country is very flat. The difference in height between coastal areas
and 500 km inland is only a few meters. This means that if sea level
would rise, or the land would collapse (which is already going on
very rapidly), most of Thailand will be under water. This means that
a lot of the 66 million population will get wet feet. To get an idea
of what will happen, the GEO2TECDI-2 research group is examining
every source of land and sea motion.
There
is one particular area where the effect of this land collapse can be
seen very clearly. This is the area around the Thai Buddhist temple
Wat Khun Samut Trawat. In 1950, this was still an inland temple
surrounded by Thai settlements. Today we can find the current state
on Google Earth
We
can clearly see that the temple is surrounded by water and that
people have built protective structures to ensure the temples present
state. Comparing the current sea shore lines with that of the 1950's
tells us that the sea has already taken 1 km of the Thailand
mainland.
The
GEO2TECDI-2 research team has accurately measured the sea
level rise in the area (tide gauges) for the past 60 years and they
found a 25 cm rise in mean sea level. However, this alone could not
represent the large land erosion seen today. With InSAR and GNSS
measurements they observed a land collapse of 1 meter!!! over the
last 60 years. This explains the dramatic geological and social
changes in the coastal areas quite well. However, this
land subsidence could not be explained by any natural
tectonic motion (1-3 mm/yr tectonic uplift and 10-15 mm/yr subsidence
after the Sumatra-Andaman earthquake) of the crust. What could it be?
They
had an excursion to the Wat Khun Samut Trawat temple. Traveling
mostly by boat and they hiked the last bit. During this travel they
encountered a lot of shrimp farms (yes, the kind from "My momma
always said..."). To grow shrimps you need fresh water (because
fresh water shrimps taste better). This fresh water could have be
taken from the Bangkok river, east of that area, but industry and
population have polluted the river water, making it unusable for
shrimp farming. Still, the shrimp farming business in that area is
booming. Despite of the law forbidding it, the fresh water
is pumped from the groundwater. This is especially clearly visible in
InSar images, which show large subsidence in areas where newly build
shrimp farms are located. Due to the groundwater pumping, the ground
is settled more firmly causing the ground to subside.
It
is impossible to ban shrimp farming, because it is
the economic driving factor in that area. But it will cause
major flooding in the near future. Thanks to the GEO2TECDI-2 research
the issue is made visible and they can inform the people of the
possible dangers. It is now up to all of us to find out what to do
with this information and hopefully find an answer to this
complicated question.
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