System Dynamics Modeling and Its Applications on Urban

Environmental ManagementMarion Micah R. Tinio

Master of Science in Environmental Science

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Outline

• Systems Thinking

• Feedback Loops

• System Dynamics Modelling

• Applications of SD Modelling in Urban Environmental Management

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Systems Thinking

Environmental issues involve phenomena consisting of interrelated components that change over time.

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Characteristics of Systems Thinking

1. Begins with a global description, then move toward the specific.

2. Focuses on dynamic processes – changes over time

3. Seeks a closed-loop explanation – set scope and limitations; behavior of the system is only dependent on elements within system

4. Identifies feedback loops

5. Looks for checks, balances, and runaway processes.

6. Focuses on cause-effect relationships

4Deaton and Winebrake (2000)

Resolving Environmental Issues

• Environmental issues are complex and different elements have interrelationships.

– OVERPOPULATION

– URBANIZATION

– CLIMATE CHANGE ADAPTATION AND MITIGATION

– RESOURCE MANAGEMENT

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Feedback Loops

• Definition

– A closed-loop circle of cause and effect

– Conditions in one part cause results elsewhere, which will act on the original conditions

– Feedback loops help to understand which elements have high and low impacts to the system.

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Types of Feedback Loops

• Reinforcing (positive)

• Balancing (negative)

Adapted from Deaton and Winebrake (2000) and Morecroft (2010)

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System dynamics modeling

• Developed by Jay Forrester in the 1950s

• A methodology in which simulation is governed entirely by changes over time, used for studying and managing complex feedback systems

• When initial conditions are assigned for variables, the model would produce related consequences based on the initiation of action and flow of information.

• It is used to understand how a system works and to predict its performance.

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Systems have four components

• A component of a system where something is accumulated. The contents may go up or down over time

Reservoirs/Stocks

• Activities that determine the values of reservoirs over time.Processes/Flows

• System quantities that dictate the rates at which the processes operate and the reservoirs change

Converters

• The cause-effect relationships between system elements.Interrelationships

Deaton and Winebrake 20009

Basic Elements of a System Dynamics Model

Flow 1

Conv erter

Stock

Flow 2

• Feedbacks• Stock-flow relationships• Time delays between elements

10STELLA

Guzman et al. 2010

Waste Management in Tuguegarao City11

Solid waste flow of the City wastranslated into a computer modelfor scenario simulation.

Guzman et al. 2010

Waste Management in Tuguegarao City12

The SD model was run with thespatial distribution of waste in mindto simulate different scenarios ofwaste management.

Nasiri et al. 2012Water reuse in Great Lakes Region

Water reuse planning that involved various economic, technological, and

environmental criteria over time

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Guan et al. 201114

System dynamics modelling is a powerful tool for complex systems with interconnected components.

Guan et al. 2011

The study combined system dynamics and GIS for integrated dynamic and spatial assessments of sustainability of Chongqing City, China..

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Summary

• Environmental issues cannot be simplified because of the interrelated components affecting the systems over time.

• Basic elements of system dynamics modelling

– Feedback loops

– Stock-flow relationships

– Time delays

• System dynamics modelling is a frontier towards resolving Philippine environmental issues.

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