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

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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.

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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

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Annual Flood DischargeYellowstone River near Livingston

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Stream Rating Curves

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Rating CurveYellowstone River near Livingston

Flood Recurrence Intervals

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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?