Transcript Teaching Earth Sciences through Spreadsheet Modeling

Modeling Earth Processes
using Spreadsheets and
Commercial Models
William Locke/David Mogk
Dept. 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
Laboratory
Mechanics
• 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
• Theory of slope
modeling
– Mass redistribution
– Running mean
20
Initial
1 step
15
5 steps
Height (m)
– Block operations
– Graphing
Scarp Profile
10 steps
10
20 steps
50 steps
5
0
0
5
10
15
-5
Distance (m)
20
25
30
0
15
Distance (m)
5
10
20
25
30
-5
20 steps
50 steps
10 steps
5 steps
1 step
Initial
Height (m)
Scarp Profile
20
15
10
5
0
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
2800
Model
Actual
2600
2400
Elevation (m)
• Competence in block
operations & graphing
• Familiarization with
absolute cell references
• Exposure to equations
3000
2200
2000
1800
1600
1400
• Interrelationships
between modeling and
collection of field data.
1200
V.E. ~ 10X
1000
0
5
10
Distance (km)
15
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
A n n u a l P e a k D is c h a r g e ( c fs )
Magnitude/Frequency
Annual Flood Discharge
Yellowstone River near Livingston
40000
Average
30000
20000
10000
0
1897
1917
1907
1937
1927
1957
1947
Water Year
1977
1967
1997
1987
Stream Rating Curves
Rating Curve
S ta g e ( fe e t)
Yellowstone River near Livingston
10
8
6
4
2
0
0
10000
20000
Discharge (cfs)
30000
40000
Flood Recurrence Intervals
D is c h a r g e ( c f s )
Yellowstone River @ Livingston
50000
12
40000
10
30000
8
20000
6
10000
4
0
2
100
1
10
Recurrence Interval (years)
Discharge
Stage
S ta g e (fe e t)
Recurrence 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
Modflow
Grid
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?