Modeling the Environment: A Call for Interdisciplinary Modeling

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

-

+constructionworker

satisfaction+

other factors such asadequacy of public

infrastructure

Vacancies Falland so does worker productivity


totalworkers

housingdemand

stock ofhouses

+

+

vacancy rate

-

+construction

workersatisfaction

+


infrastructure

construction workerturnover

construction workerproductivity

-

-

Lower productivity means we need to hire still more workers!


totalworkers

housingdemand

stock ofhouses

+

+

vacancy rate

-

+constructionworker

satisfaction+


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


f raction f emale



number of redds



smolts enter ocean



eggs per redd


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






Months in Each Stage of the Life Cycle

6

12

1

12 12

4

1 48 month

life cycle

emergent f ry


f raction f emale



number of redds



smolts enter ocean



eggs per redd


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






Parameters

50%

90%

35% 10%

25%

50%3,900

Density Dependent

Juvenile Loss Depends on Density

10.0

50,000100,000150,000200,000250,000300,000350,000400,000

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

Untitled

Page 10.00 120.00 240.00 360.00 480.00

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

Page 10.00 120.00 240.00 360.00 480.00

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.

Documents

Modeling the Environment: A Call for Interdisciplinary Modeling