UTILIZING 3D GIS MODELING TECHNIQUES TO BETTER UNDERSTAND THE REGIONAL SUBSURFACE GEOLOGY OF BANGLAD

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UTILIZING 3D GIS MODELING TECHNIQUES TO BETTER
UNDERSTAND THE REGIONAL SUBSURFACE GEOLOGY OF
BANGLADESH
With possible insights into arsenic contamination
issues
muse.jhu.edu
Summer Brown, Department of Geosciences, Virginia
Tech
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Elevated levels of arsenic in groundwater have
spawned an epidemic within Bangladesh.
This has caused adverse health effects including
hyperpigmentation, keratosis, and numerous forms
of cancer.
web.worldbank.org
Began with the installation of 6 to 10 million
tube wells to dissuade drinking of microbially
contaminated surface water.
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25 of the wells sampled by the British
Geological Survey (BGS) showed arsenic
concentrations in excess of 50 ug/L.
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Many questions are left unanswered regarding the
cause of the groundwater contamination.
Perhaps the best step to take is to ensure
confidence in the foundation many important
assumptions are based upon.
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A complete understanding of the three-dimensional
regional geology would provide an ideal basis for
future research and mitigation efforts.
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To accomplish this, 3D models will be developed,
primarily utilizing preexisting data.
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GIS applications are a practical way to relate
regional geology to the suggested sources,
mechanisms, and mitigation of the arsenic.
Geographical Information Systems (GIS) have been
successfully used for both two and
three-dimensional modeling.
3D models of the subsurface would be especially
useful for

• determining the relationship between the shallow
  and deep aquifers
• finding the locations and structure of peat
  layers
• putting geologic controls on arsenic release and
  transport

A beneficial aspect of 3D modeling, is that it
can reveal flaws unseen in the original
two-dimensional interpretations.
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Two programs which are potentially useful for
this project are ArcScene and EarthVision.
A 3D analyst extension of ArcView which can be
combined with a database (from geophysical,
surface, well, etc) to create extremely useful
subsurface models.As an example, ArcView was
used in Brussels to gain a better visual
understanding of regional seismic hazards.
ESRI, 2006
EarthVision, is a user-friendly tool. The
software is intuitive, allowing easier modeling
of geologic structures from geophysical and drill
data. It automatically performs time to depth
conversions for seismic data, which can save
considerable time.
DGI, 2006
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Developing a set of 3D models using GIS would
provide a basis for better understanding arsenic
release and transport.
Elevated levels (50 ug/L in some cases) of
arsenic in tube wells have caused health problems
across Bangladesh.
3D models will be developed, primarily utilizing
preexisting data, to help answer questions
regarding the cause of contamination.

• These would be useful for determining -
  relationship between the shallow and deep
  aquifers
• - locations and structure of peat layers
• - geologic controls on arsenic release and
  transport

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Questions?