Modeling the Environment: A Call for Interdisciplinary Modeling 1 st Edition: 1999 2 nd Edition: 2009 (the benefits of interdisciplinary modelin using system dynamics)
Jan 02, 2016
Modeling the Environment:A Call for Interdisciplinary Modeling
1st Edition: 1999
2nd Edition: 2009(the benefits of
interdisciplinary modelingusing system dynamics)
A Boom Town Story
constructionworkers atproject site
totalworkers
housingdemand
stock ofhouses
+
+
vacancy rate
-
+construction
workersatisfaction
+
other factors such asadequacy of public
infrastructure
Vacancies Falland so does worker productivity
constructionworkers atproject site
totalworkers
housingdemand
stock ofhouses
+
+
vacancy rate
-
+construction
workersatisfaction
+
other factors such asadequacy of public
infrastructure
construction workerturnover
construction workerproductivity
-
-
Lower productivity means we need to hire still more workers!
constructionworkers atproject site
totalworkers
housingdemand
stock ofhouses
+
+
vacancy rate
-
+construction
workersatisfaction
+
other factors such asadequacy of public
infrastructure
construction workerturnover
construction workerproductivity
-
-
normal need forconstruction workers
-
+
TheViciousCircle
Conclusion of the Boom Town Story
• Everybody knew about the vicious circle; but nobody would simulate it
• Leaving planners to do so in their head
• Insight for some companies: the boom town problem is “our problem” not “their problem”
Another Storyfrom the Electric Power Industry
in the 1970s-1980s
The Vicious Circle Makes the Headlines
The Vicious Circle that Utilities Can’t Seem to Break:new plants are forcing rate increases-further cutting the growth in demand
The Electricity Curve Ball:declining demand and increasing rates.
The Death Spiral
The Death Spiral in Context
electricityconsumption
actual price ofelectricity
indicated priceof electricity
allowedrevenues
value of therate base
constructionstarts
forcecasted needfor capacity
++
installedcapacity
-
+ ++
+
-
-
constructioncompletitions
+
+
the deathspiral
(+)capacity
expansion (-)
delayeddemandcontrol
(-)
Linking Existing Models TogetherDoesn’t Work
OK, let’s build a single model(a Corporate Model)
•Workshop by EPRI: 1 of 12 models did the spiral
•Workshop for Dept. of Energy: 1 of 13 models did the spiral
•Most managers had to simulate the spiral in their head
Conclusions from the “Spiral Study”
• Waiting for regulators to raise rates won’t necessarily solve the financial problems
• The IOUs could improve their situation by building smaller, shorter-lead time plants
• And by slowing the growth in electricity demand through efficiency programs
The 1980s: The Move to Small Scale
Shift to Small Scale
The Difficult Years
1880s 1890s 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s
1882: Pearl Street Station
AC versus DC
Samuel Insull and the IOUs
The Depression & Federal Power
The Golden Years
Nat. Gas and Deregulation
•Cancellation of nuclear plants•Shift to smaller coal plants•Invest in PURPA cogeneration•Utility conservation programs
Teaching Interdisciplinary Modeling
•WSU System Dynamics, Environmental Science
•Growing Student Interest
•Faculty Interest: NSF Grant for Doctoral Training
•Remainder of the Talk: one student learns the value of interdisciplinary modeling
The Salmon of the Tucannon River
The Tucannon
River
Eggs & Emergent Fry
The Salmon Life Cycle
Juveniles: Spend One Year Competing for Space in the Habitat
The Smolt
Migration
p. 155: Around 22,000 Returning Adults
Is ~20 Thousand Salmon
Plausible?
The Columbia Basin drainage is around 800
times larger than the Tucannon.
800 times 20 thousand gives around 16 million
adults returning to the mouth of the Columbia each year!
The Salmon Model
emergent f ry
smolts leav e Tucannon
f raction f emale
Two Yr Olds in Ocean
adults arriv e at
spawning grounds
number of redds
adult migration loss
One Yr Olds in Ocean
smolts enter ocean
adult migration loss f raction
adults return to Columbia
eggs per redd
juv eniles in the riv er
Eggs in Redds
egg deposition
egg loss
egg loss f raction
loss in 1st y ear
smolts in migration
adult maturation
juv enile loss
loss in 2nd y ear
Adults in Migration
smolt migration loss
juv enile loss f raction
depends on density
loss f raction f or 1st y r loss f raction f or 2nd y r
Adults Ready to SpawnAdults Spawning
smolt migration loss f raction
emergent f ry
smolts leav e Tucannon
f raction f emale
Two Yr Olds in Ocean
adults arriv e at
spawning grounds
number of redds
adult migration loss
One Yr Olds in Ocean
smolts enter ocean
adult migration loss f raction
adults return to Columbia
eggs per redd
juv eniles in the riv er
Eggs in Redds
egg deposition
egg loss
egg loss f raction
loss in 1st y ear
smolts in migration
adult maturation
juv enile loss
loss in 2nd y ear
Adults in Migration
smolt migration loss
juv enile loss f raction
depends on density
loss f raction f or 1st y r loss f raction f or 2nd y r
Adults Ready to SpawnAdults Spawning
smolt migration loss f raction
Months in Each Stage of the Life Cycle
6
12
1
12 12
4
1 48 month
life cycle
emergent f ry
smolts leav e Tucannon
f raction f emale
Two Yr Olds in Ocean
adults arriv e at
spawning grounds
number of redds
adult migration loss
One Yr Olds in Ocean
smolts enter ocean
adult migration loss f raction
adults return to Columbia
eggs per redd
juv eniles in the riv er
Eggs in Redds
egg deposition
egg loss
egg loss f raction
loss in 1st y ear
smolts in migration
adult maturation
juv enile loss
loss in 2nd y ear
Adults in Migration
smolt migration loss
juv enile loss f raction
depends on density
loss f raction f or 1st y r loss f raction f or 2nd y r
Adults Ready to SpawnAdults Spawning
smolt migration loss f raction
Parameters
50%
90%
35% 10%
25%
50%3,900
Density Dependent
Juvenile Loss Depends on Density
10.
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
Emergent Fry (mil lions)
The Beverton-Holt Curve: page 154
Carrying Capacity = 400,000
Fraction SurviveAt lowDensity
= 0.5
KeyLoops
eggs inredds
emergent fry
juvenile lossfraction
carryingcapacityfor the
Tucannon
juvenileloss
juveniles in theTucannon
smolts inmigration tothe ocean
adults in theocean
adultsreturning
to theColumbia
adults inmigration
adultsspawning
in theTucannon
++
+
+ +
+
+
+
+
+
-
-
(+)Population
Growth (-) Density
DependentControl
Do We Get S-Shaped Growth Under Undisturbed Conditions?
Do We See Large Variations?
Do We See A Decline in Returns From Development?
50% Harvesting Starting in 120th Month
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Months
1:
1:
1:
0.00
20.00
40.00
1: adults return to Columbia
1 1 1 1
Remainder of 50% Harvesting Simulation
Untitled
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Months
1:
1:
1:
0.00
20.00
40.00
1: adults return to Columbia
1 1 1 1
Focus on Harvesting
Discussion of Harvesting• Typical results
– One team after another finds a sustainable harvest– The salmon population has a natural resilience
• Contrast with Fisheries around the world– Fish Banks Game (Meadows)– Norwegian Fjord Experiment (Moxnes)– Fish and Ships (Morecroft)
• Over-investment in renewable resources is common– Too many irrigated acres; too little river flows– Too many steers; not enough grazing land– Too many sawmills; not enough harvestable trees
Example of a Student ProjectMigration Inputs Habitat Inputs
Project Idea: Simulate Carrying Capacity in the Model
Student’s Stocks & Flows
start with 25 miles of “Degraded
River” with a
capacity of 1 thousand smolts/mile
Fully Restored River
the other 25 miles of
habitat is “Mature Restored
River” with 8.3 thousand smolts/mile
Information Buttons in Student Model
Restoration Spending
For example: 25 miles @ $52 per foot:
It takes around $7 million to restore the river.
Nature Completes the Job
The student assumed that nature will convert recent restored miles to mature habitat at the
rate of 10% per year.
River restored; adult counts are up; not surprising!
The surprise comes when you experiment with the harvest fraction.
Nearly Finished on $7 million project
The adult returns are climbing; we are trying 85% harvesting
Continuing with 85% harvesting: the Governor is happy with the $5 million in value
Finish the Experiment @ 85% harvesting
Harvest is sustainable; Value of harvested fish exceeds $7 million!
One Student Sees the Value of Interdisciplinary Modeling
I’m a fluvial-geomorphologist. I would never have combined
river restoration calculations with population biology in this manner.
Surprised by the result.Surprised by his ability to get the result
Close with one student’s wish: With better understanding
might come better strategies to rebuild the salmon runs.