Numerical
Modeling
One
of the primary goals of the Consortium
was to leverage advanced computing
and visualization technologies "to
bring alive the complex interplay
of natural and human forces shaping
the Mississippi River Basin."
(NSF proposal, May1998) Also important
to the Consortium was that all visual
representations and activities in
the DRB should emulate current scientific
methodologies and tools as closely
as possible and therefore be grounded
not on "canned but rather
on genuine scientific data. We relied
on three sources for such data.
- Acquired
data (e.g., historic flow, bathymetry,
elevation, land cover).
- Pre-constructed
geometric models of selected landscape
and cultural features (eg., trees,
grass cover, bridges, buildings).
- Pre-computed
outputs of numerical simulations
based on mathematical models
of dynamic phenomena, such as channel
flow, runoff, erosion, sediment
transport, and the effects of levees
and dams on river basin hydrology.
These simulations provide the data
for many of the activities currently
available in the DRB.
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For
example, a two dimensional finite-element
grid simulation was used to calculate
channel flow velocity, and water
surface elevation. |
These
outputs were fed into other computer
models to simulate the location,
velocity, and direction of a tow
barge in the River
Pilot Simulator, to compute
sediment transport in conjunction
with archival sediment load data,
and to compute the numerical data
for DRB activities such as Make
It Flood, Remove a Dam,
and Change a Levee. |
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Flow
velocity and extent ->
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Levee
in place
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Remove
Levee
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Looking
beyond the river channel and onto
the adjoining land, yet different
models were used to simulate the
amount, direction, and velocity
of overland flow (rainfall runoff),
and the extent of soil erosion
or deposition at each location
on a grid. These second sets of
simulation data underpin the following
DRB activities: Make It Rain,
Track Sediment, and Examine Erosion. |
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Hardware
constraints dictated that all simulation
data be pre-computed at the GMSlab
then archived in the DRB database.
Nevertheless, all model outputs were
visualized in real time in response
to visitor requests initiated through
the above DRB-supported activities.
Future development of the DRB might
accommodate real time numerical simulations
that afford visitors greater freedom
to explore their own "hypotheses"
by increasing the number of "what
if" scenarios that can be investigated.
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