Modeling Earth Processes using Spreadsheets and Commercial Models William Locke/David Mogk Dept. of...
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Transcript of Modeling Earth Processes using Spreadsheets and Commercial Models William Locke/David Mogk Dept. of...
Modeling Earth Processes using Spreadsheets and
Commercial Models
William Locke/David MogkDept. of Earth Sciences
Montana State University, Bozeman MT
Why Modeling?• Effective learning is experiential!
• Substitute arithmetic/mathematics for:– Space
• Loess deposition– Time
• Thrust-belt evolution– Safety
• Thermohaline circulation– Money!
What do modelers do?
• “A major purpose of scientific investigation is to describe reality through models” Gauch, 1993, Am. Sci., 81, 468.
• “..what some researchers are calling the ‘third branch of science’ - using…computers to simulate physical processes..” Pool, 1993, Science, 260, 1077.
• “..predict the future state of a system with tolerable certainty” Denning, 1990, Am. Sci., 78, 496.
Caveats(Denning, 1990, American Scientist, 78, 498)
• “We must come to understand the domains over which a given model is reliable..”
• “Systems whose rules can…change in unpredictable ways are unlikely to have a reliable…model.”
• “…it is easy to substitute the model for reality and to confuse our opinions with ‘scientific facts’ supported by the model.”
Why Spreadsheets?
• Ubiquitous– AppleWorks, Microsoft Works, Quattro, Lotus…
• Visually Powerful Graphics– 2-D (XY, Line), 3-D (Ribbon, Surface)…
• “Translucent” - not “Black Box”– point-and-click cell contents
• “What-if?”– real-time graphical response to changing inputs
Modeling in ESCI 307 - “Principles of Geomorphology”
• Assumption:– One application is “Exposure”– Two applications are “Familiarization”– Three applications are “Competence”– Four applications are “Mastery”
• How far do you want to get this year?• Mastery of spreadsheet skills - exposure to and
familiarization with specific applications
LaboratoryMechanics
• Traphagen 100• 10 computers (in pairs,
out-facing) + instrux.• Teams of 2 or 4• Face in for “lecture”,
map work, specimens• One instructor and a
teaching assistant are generally required.
SCARP1 - Scarp Evolution
• Exposure to spreadsheet practice– Block operations– Graphing
• Theory of slope modeling– Mass redistribution– Running mean
Scarp Profile
-5
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0 5 10 15 20 25 30
Distance (m)
He
igh
t (m
)
Initial
1 step
5 steps
10 steps
20 steps
50 steps
0 5 10 15 20 25 30
Initi
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1 s
tep
5 s
tep
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ps
20
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ps
50
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ps
-5
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He
igh
t (m
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Distance (m)
Scarp Profile
Outcomes - SCARP1
• “Way-cool graphics!”
• “I already knew that.”
• “Oops! I lost it!”
• “It’s not real” but “Material eroded from the top accumulates at the bottom”.
• “It looks like chemical diffusion.”
• “Measure all of the possible variables and the slope responses.”
Discussion - Scarp1
• Do you use spreadsheets, personally?– If so, why - what do you find useful?
• Is a lab teaching spreadsheeting worthwhile?
• Is the graphical capability valuable for other applications than modeling?
SCARP2 - Scarp Evolution• Familiarization with
– Block ops. & Graphing
• Exposure to– Absolute cell refs.
• Practice of slope modeling– Acceleration of gravity– Disequilibrium -
“Erosivity”
Outcomes - SCARP2
• “It looks just like SCARP!”• “You didn’t really include all of the
variables.”• “How do I:
– add a resistant layer?”– mimic a deluge?”– model a stream at the toe?”– …?”
Discussion - SCARP2
• Is this a good way to learn about the effects of g•sin?
• Is this a good way to learn about probabilistic natural processes?
• Is it worth doing additional exercises?
LONGPRO - Stream Evolution
• Competence in block operations & graphing
• Familiarization with absolute cell references
• Exposure to equations
• Interrelationships between modeling and collection of field data.
1000
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0 5 10 15
Distance (km)
Ele
vat
ion
(m
)
Model
Actual
V.E. ~ 10X
Outcomes - LONGPRO
• About 70% of teams “succeed” - matching real and modeled profiles (but with unreal parameters - e.g., a tiny output of m-scale particles).
• About 40% of teams succeed.– Success requires changing one variable away
from the optimal solution, then another one towards it.
Discussion - LONGPRO
• Is the integration of field data with modeling worth the investment of two laboratory periods?
• Is the failure rate (30% total, 60% partial) acceptable given the complexity of natural systems?– Do those who don’t succeed, fail?
GLACPRO - Glacier Reconstruction
• Mastery of block operations and graphing
• Introduction to research– Team activity– Resource allocation– Interaction with other
groups– Quality control
Outcomes - GLACPRO
• A surprising number of results are incorrect.– No intuitive knowledge of what a glacier
“should look like”.
• Great difficulty meeting as teams outside of class.
• Inevitable team friction.
• Publishable products (when “massaged”).
Discussion - GLACPRO• Is the difference between “glacial extent” and
“modeled glacial extent” clear?
• Are team/interactive exercises worth the degradation of content?
• Are exercises with no “right answer” fair to students (as for grading purposes)?
Data Downloading
• Sources– USGS
– Other?
• Formats– Parsing
– Web Tables X• Outcomes
– Trends
– Statistics
Log10 transformation
Magnitude/Frequency
0
10000
20000
30000
40000
Annual P
eak D
ischarge (
cfs
)
18971907
19171927
19371947
19571967
19771987
1997
Water Year
Annual Flood DischargeYellowstone River near Livingston
Average
Stream Rating Curves
0
2
4
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Sta
ge (
feet)
0 10000 20000 30000 40000 Discharge (cfs)
Rating CurveYellowstone River near Livingston
Flood Recurrence Intervals
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Dis
charge (
cfs
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Sta
ge (
feet)
1 10 100 Recurrence Interval (years)
DischargeStage
Yellowstone River @ LivingstonRecurrence Intervals (n=73)
Discussion - Download
• What numerical data sets exist?
• Does spreadsheet manipulation result in increased learning effectiveness?
• Would a field trip to a stream gauge be a more effective teaching tool?
Virtual MODFLOW
• The standard in professional groundwater modeling - $750 (incl. academic discount!)
• The Scientific Software Group: http://www.scisoftware.com/
• Downloadable demo: http://www.scisoftware.com/products/visual_modflow_demo/visual_modflow_demo.html
ModflowGrid
Discussion of Visual MODFLOW
• Is it appropriate to use a commercial product for a class activity?
• Is “black-box modeling a valuable learning tool?
General Modeling Issues
• At what academic level is modeling critical?
• Relative importance of physical, theoretical and mathematical models?
• Optimal execution - homework, solo lab, team lab, class demo…?
• Optimal tradeoff against content, field trips, map exercises, quizzes…?
General Issues relating to DLESE
• Who should maintain such models?– Author? DLESE? Other agency?
• How can DLESE promote this activity?
• Action Items?– User Group?– “White Paper” on modeling pedagogy?– Testing Service for models?