Chariya,
I would suggest reading the full National Academy of
Science Report regarding the allegations surrounding
the "Inland Navigation System Planning: The Upper
Mississippi River-Illinois Waterway" project
(UMR-IWW).
http://www.nap.edu/books/0309074053/html/
For the larger community, Chapter 5 of the report,
which outlines "the current state of the art in
modeling the uncertainty associated with forecasting
future events" they never mention System Dynamics.
In fact, I searched the entire book for even one
mention of using System Dynamics and found nothing.
What gives? Surely, SD has something to offer to this
type of complex analysis?
For Chariya and others interested in the details . . .
The report starting at page 30 begins discussing the
role of the environment as being an important
consideration in planning to expand locks (WOW -- what
an insight, to think that the environment might be
impacted by expanding locks!) As the report puts it:
"A true systems view of the UMR-IWW would acknowledge
that a thourough understanding of the current state of
the Upper Mississippi Rive and floodplain ecosystem
must be related to structural modifications in the
Upper Mississippi River basin, to operations of the
UMR-IWW navigation system, and to ecosystem responses
to a range of natural and anthropogenic influences
within the Upper Mississippi River basin. The
feasibility studey would also benefit from a
clarification of the roles of the environmental
studies in the decision-making process regarding lock
extensions."
The report talks about the two models developed: (1) a
spatial equilibrium model and (2) the ESSENCE model.
What is spatial equilibrium modeling (SEM)? Sounded
strange and mysterious, so I did some quick reading.
SEM is basically an economic approach to trying to
understand complexity. It is evidently often used to
analyze international agricultural trade. Based on
what I found, spatial equilibrium models usually
operate under assumptions of perfect competition, but
from a quick look on google, its obvious that people
are adapting it to deal with imperfect competition.
The equation you mention is related to the simulation
ESSENCE model (an excel spreadsheet model containing
two main components and one smaller component that
calculated the economic benefit of the waterway).
According to the report, these components are then
"reconciled using Excels "solver" function (page 36
of the report).
Q=[(R-y)/(R-W(o))]^N * Q(o)
To summarize the reports comments on the four key
weaknesses of the Corps Model:
1. Forecasting of domestic and foreign commodity
production and use is based mostly on extrapolations
of historical data (The Corp evidently used USDA
forecasts). Forecasts made in 1994 for 1995-2000 were
inaccurate (example: model forecasted increases in
grain exports: reality was that total exports of corn
and wheat trended downward). From what I read, I
believe that the orginal Corps report was seeking to
create projections for *50* years into the future.
There was some confusion regarding which data to use
for regression analysis. As I read this report, I
shuddered to think about using Excel to create this
type of model.
****Does anyone know if the USDA is now using SD
modeling software to create large-scale agricultural
sector models?
2. Determining the sensitivity of waterway tonnage to
barge tarifffs was based on assumptions that were not
realistic. In the equation, the exponent N represented
an empiraclly determined constant that was open to
serious debate (to put it mildly).
3. Calculating National Economic Development benefits.
This is a whole section that calls into question data
used in the model and certain techniques. Enjoy
reading!
4. Modeling lock congestion was done using a simple
queing model to model increase in delays at locks in
response to traffic increases. They recommend that
simulation modeling (rather than queing theory) be
used to analyze lock performance. Do they mean SD
simulation modeling or are they talking about
something else? I dont know. Does anyone?
Best,
Justin
From: Justin Lyon <justin1028@yahoo.com>
Other interesting tidbits . . .
http://www2.mvr.usace.army.mil/umr-iwws ... background
http://www2.mvr.usace.army.mil/umr-iwws ... n=home.faq
Army Corps of Engineers Waterway Projects.
-
- Junior Member
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- Junior Member
- Posts: 2
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Army Corps of Engineers Waterway Projects.
DEAR JUSTIN, CHARIYA AND EVERYBODY ELSE CONCERNED WITH OUR WORLD,
it seems that we just love to mess up the environmental balance within our major river
systems. in australia it is the murray darling system, in europe its the rhyne, in eastern
europe its the danube, in latin america its the amazon (late starter but catching up), and in
the good old usa its the mighty missippii. but theres more i could mention.
the bigger the river system, the bigger the problem.
although this area of sd is not in my area of immediate interest, i understand from my
involvement with australian agriculture/horticulture in the murray darling rivers system that it
has to be brought back into balance in order to achieve some level of sustainability. some
will say that it is already in balance, even so we need to understand the dynamic relationship
within the system in order to manage it properly.
surely, the same basic and standardised systems thinking methodology can be applied with
minor modification by the authorities which manage these systems, to preseve our global
ecosystem.
the current fragmented problem solving to this issue wont achieve much.
the challenge is for the sd zealouts around the world to sell systems thinking to the water
management authorities globally in order to establish universal performance benchmarks for
balanced and sustainable waterways management. a global standards body is one option for
achieving this.
ill get down off my soap box now. further comments encouraged.
may the earth be with you!
regards
michael barrett
From: fivebeesplus@iprimus.com.au
it seems that we just love to mess up the environmental balance within our major river
systems. in australia it is the murray darling system, in europe its the rhyne, in eastern
europe its the danube, in latin america its the amazon (late starter but catching up), and in
the good old usa its the mighty missippii. but theres more i could mention.
the bigger the river system, the bigger the problem.
although this area of sd is not in my area of immediate interest, i understand from my
involvement with australian agriculture/horticulture in the murray darling rivers system that it
has to be brought back into balance in order to achieve some level of sustainability. some
will say that it is already in balance, even so we need to understand the dynamic relationship
within the system in order to manage it properly.
surely, the same basic and standardised systems thinking methodology can be applied with
minor modification by the authorities which manage these systems, to preseve our global
ecosystem.
the current fragmented problem solving to this issue wont achieve much.
the challenge is for the sd zealouts around the world to sell systems thinking to the water
management authorities globally in order to establish universal performance benchmarks for
balanced and sustainable waterways management. a global standards body is one option for
achieving this.
ill get down off my soap box now. further comments encouraged.
may the earth be with you!
regards
michael barrett
From: fivebeesplus@iprimus.com.au
-
- Junior Member
- Posts: 7
- Joined: Fri Mar 29, 2002 3:39 am
Army Corps of Engineers Waterway Projects.
Anyone has, or know of anyone who has, done any study on the dynamic
modeling of the Missouri river navigation effort of the Army Corps. I
would appreciate any pointer to research papers on this subject. In fact,
any research paper on environmental study related to the Army Corps
(Sweeneys original report that contains the famous equation I read about in
the Washington Post.
Q = someting (a - b)/c - d) * n ?
would be nice
Thanks,
chariya
From: "Chariya Peterson" <Chariya.Peterson@verizon.net>
modeling of the Missouri river navigation effort of the Army Corps. I
would appreciate any pointer to research papers on this subject. In fact,
any research paper on environmental study related to the Army Corps
(Sweeneys original report that contains the famous equation I read about in
the Washington Post.
Q = someting (a - b)/c - d) * n ?
would be nice
Thanks,
chariya
From: "Chariya Peterson" <Chariya.Peterson@verizon.net>
-
- Junior Member
- Posts: 7
- Joined: Fri Mar 29, 2002 3:39 am
Army Corps of Engineers Waterway Projects.
Dear all,
Good thing is, the USs Environmental Protection Agency (EPA) is developing
Environmental Data Exchange (EDX) system where data from US states and
regional departments will be integrated and accessible to us. Building an
SD model to predict potential environmental catastrophy will succeed only if
we have a good source of data to guide and feed the model and a data
excahnge like EDX would be very useful.
I am looking forward to spend this holiday weekend studying Andys and
Justoins suggestions. Thanks.
chariya
From: "Chariya Peterson" <Chariya.Peterson@verizon.net>
Good thing is, the USs Environmental Protection Agency (EPA) is developing
Environmental Data Exchange (EDX) system where data from US states and
regional departments will be integrated and accessible to us. Building an
SD model to predict potential environmental catastrophy will succeed only if
we have a good source of data to guide and feed the model and a data
excahnge like EDX would be very useful.
I am looking forward to spend this holiday weekend studying Andys and
Justoins suggestions. Thanks.
chariya
From: "Chariya Peterson" <Chariya.Peterson@verizon.net>
-
- Junior Member
- Posts: 7
- Joined: Fri Mar 29, 2002 3:39 am
Army Corps of Engineers Waterway Projects.
Justin,
Thank you for the pointer to the NAP document. It is an eye opener. If the
result of the Corps analysis effort is also accessible, it might be fun to
create a model to simulate Don Sweeneys empirical result ( the Q, the R
and the N )
Having an SD model will make it a lot easier to do scenario analysis, and
perhaps also for Monte Carlo analysis.
Please correct me if I am wrong, a (logically correct) SD can be used in
Monte Carlo simulation by replacing the weight of each exogenous variable by
all possible values (i.e. a whole range of probability distribution).
chariya
From: "Chariya Peterson" <Chariya.Peterson@verizon.net>
Thank you for the pointer to the NAP document. It is an eye opener. If the
result of the Corps analysis effort is also accessible, it might be fun to
create a model to simulate Don Sweeneys empirical result ( the Q, the R
and the N )
Having an SD model will make it a lot easier to do scenario analysis, and
perhaps also for Monte Carlo analysis.
Please correct me if I am wrong, a (logically correct) SD can be used in
Monte Carlo simulation by replacing the weight of each exogenous variable by
all possible values (i.e. a whole range of probability distribution).
chariya
From: "Chariya Peterson" <Chariya.Peterson@verizon.net>