2.systems and models new

Models and the

behavior of systems

BY

GURU

GURU IBESS/GURU/SYSTEMS & MODELS

Syllabus Statements

1.1.1: Outline the concept and characteristics of a

system

1.1.2: Apply the systems concept on a range of scales

1.1.3: Define the terms open system, closed system,

isolated system

1.1.4: Describe how the first and second laws of

thermodynamics are relevant to environmental systems

1.1.5: Explain the nature of equilibria


Syllabus Statements

1.1.6: Define and explain the principles of positive and

negative feedback

1.1.7: Describe transfer and transformation processes

1.1.8: Distinguish between flows (inputs and outputs),

and storages (stock) in relation to systems.

1.1.9: construct and analyze quantitative models

involving flows and storages in a system

Evaluate the Strengths and limitations of models


Vocab

Entropy

Equilibrium

Feedback

Negative Feedback

Positive Feedback

Model

Stable Equilibrium

Steady State Equilibrium

System

Closed System

Isolated System

Open system


Systems

A system is a set of components that…

1. Function and interact in some regular, predictable

manner.

2. Can be isolated for the purposes of observation

and study.


Systems on Many Scales

Ecosystem – The everglades in South FL

Biome – Tropical Rainforest

The entire planet – Gaia hypothesis


Coral Reef

Ecosystem

Most diverse

aquatic ecosystem

in the world

-------

Open systems exchange matter

and energy with

the surroundings


Closed systems exchange energy but not

matter. – don’t naturally occur on earth

Biosphere II Built as self sustaining closed system in 1991 in Tuscon, AZ

Experiment failed when nutrient cycling broke down GURU IBESS/GURU/SYSTEMS & MODELS

Nutrient cycles Approximate closed

systems as well


Isolated systems exchange neither matter nor

energy with the surroundings

Only possible though

unproven example is

the entire cosmos


Components of systems

Inputs = things entering the system matter, energy, information

Flows / throughputs = passage of elements within the system at certain rates (transfers and transformations)

Stores / storage areas = within a system, where matter, energy, information can accumulate for a length of time (stocks)

Outputs = flowing out of the system into sinks in the environment


Discharge of untreated municipal sewage

(nitrates and phosphates)

Nitrogen compounds produced by cars

and factories

Discharge of treated municipal sewage

(primary and secondary treatment:

nitrates and phosphates)

Discharge of detergents

( phosphates)

Manure runoff from feedlots

(nitrates, phosphates,

ammonia)

Dissolving of

nitrogen oxides

(from internal combustion

engines and furnaces)

Runoff and erosion

(from cultivation,

mining, construction,

and poor land use)

Runoff from streets,

lawns, and construction

lots (nitrates and

phosphates)

Lake ecosystem

nutrient overload

and breakdown of

chemical cycling

Natural runoff (nitrates and phosphates

Natural runoff (nitrates and phosphates

Inorganic fertilizer runoff (nitrates and phosphates)

To assess an area you must treat all levels of the system GURU IBESS/GURU/SYSTEMS & MODELS

Water 0.000002 ppm

Phytoplankton 0.0025 ppm

Zooplankton 0.123 ppm

Rainbow smelt 1.04 ppm

Lake trout 4.83 ppm

Herring gull 124 ppm

Herring gull eggs 124 ppm

Individuals work as well


Types of Flows: Transfer vs.

Transformation

Transfers flow through the system, involving a

change in location

Transformation lead to interactions in the

system, changes of state or forming new end

products

-Example: Water processes

Runoff = transfer, Evaporation = transformation

Detritus entering lake = transfer, Decomposition

of detritus is transformation


Precipitation

Precipitation

to ocean Evaporation

Evaporation

From

ocean

Surface runoff

(rapid)

Ocean storage

Condensation

Transpiration

Rain clouds

Infiltration and

percolation

Transpiration

from plants

Groundwater movement (slow)

Groundwater movement (slow)

Runoff Runoff

Surface runoff (rapid) Surface runoff (rapid)

Precipitation

What type of System is this?

Name the inputs, outputs, transfers and transformations GURU IBESS/GURU/SYSTEMS & MODELS

Systems and Energy

We see Energy as an input, output, transfer, or transformation

Thermodynamics – study of energy

1st Law: Energy can be transferred and transformed but it can never be created nor destroyed

So…

All energy in living systems comes from the sun

Into producers through photosynthesis, then consumers up the food web


Sun

Producers (rooted plants)

Producers (phytoplankton)

Primary consumers (zooplankton)

Secondary consumers (fish)

Dissolved

chemicals Tertiary consumers

(turtles)

Sediment

Decomposers (bacteria and fungi)

Energy at one level must come from

previous level


Using the first law of thermodynamics explain why the energy

pyramid is always pyramid shaped (bottom bigger than top)


2nd Law: With every energy transfer or transformation energy dissipates (heat) so the energy available to do work decreases

Or in an isolated system entropy tends to increase spontaneously

Energy and materials go from a concentrated to a dispersed form The concentrated high quality energy is the potential energy of the system

The system becomes increasingly disordered

Order can only be maintained through the use of energy


Heat Heat Heat Heat

Heat

Heat

Heat

First Trophic

Level

Second Trophic

Level

Third Trophic

Level

Fourth Trophic

Level

Solar

energy

Producers (plants)

Primary consumers (herbivores)

Tertiary consumers

(top carnivores)

Secondary consumers (carnivores)

Detritivores

(decomposers and detritus feeders)

Heat Heat


What results from

the second law of

Thermodynamics?


Feedback loops

Self regulation of natural systems is achieved by the

attainment of equilibrium through feedback systems

Change is a result of feedback loops but there is a

time lag

Feedback occurs when one change leads to another

change which eventually reinforces or slows the

original change.

Or…

Outputs of the system are fed back into the input GURU IBESS/GURU/SYSTEMS & MODELS

Positive feedback

A runaway cycle – often called vicious cycles

A change in a certain direction provides output that further

increases that change

Change leads to increasing change – it accelerates deviation

Example: Global warming

1. Temperature increases Ice caps melt

2. Less Ice cap surface area Less sunlight is reflected away

from earth (albedo)

3. More light hits dark ocean and heat is trapped

4. Further temperature increase Further melting of the ice


Solar

radiation Energy in = Energy out

Reflected by

atmosphere (34%)

UV radiation

Absorbed

by ozone

Absorbed

by the earth

Visible

light

Lower stratosphere

(ozone layer)

Troposphere

Heat

Greenhouse

effect

Radiated by

atmosphere

as heat (66%)

Earth

Heat radiated

by the earth


Negative feedback

One change leads to a result that lessens the original

change

Self regulating method of control leading to the

maintenance of a steady state equilibrium

Predator Prey is a classic Example

Snowshoe hare population increases

More food for Lynx Lynx population increases

Increased predation on hares hare population declines

Less food for Lynx Lynx population declines

Less predation Increase in hare population


Remember hare’s prey and other predators also have an effect GURU IBESS/GURU/SYSTEMS & MODELS

Most systems change

by a combination of

positive and negative

feedback processes


Which of the populations show positive feedback?

Which of the populations show negative feedback? GURU IBESS/GURU/SYSTEMS & MODELS

Positive or Negative?

If a pond ecosystem became polluted with nitrates, washed off agricultural land by surface runoff, algae would rapidly grow in the pond. The amount of dissolved oxygen in the water would decrease, killing the fish. The decomposers that would increase due to the dead fish would further decrease the amount of dissolved oxygen and so on...

A good supply of grass for rabbits to eat will attract more rabbits to the area, which puts pressure on the grass, so it dies back, so the decreased food supply leads to a decrease in population because of death or out migration, which takes away the pressure on the grass, which leads to more growth and a good supply of food which leads to a more rabbits attracted to the area which puts pressure on the grass and so on and on....


End result? Equilibrium…

A sort of equalization or end point

Steady state equilibrium constant changes in all directions maintain a constant state (no net change) – common to most open systems in nature

Static equilibrium No change at all – condition to which most natural systems can be compared but this does not exist

Long term changes in equilibrium point do occur (evolution, succession)

Equilibrium is stable (systems tend to return to the original equilibrium after disturbances)


Equilibrium generally maintained by negative

feedback – inputs should equal outputs



You should be able to

create a system model.

Observe the next two society

examples and create a model

including input, flows, stores

and output


High Throughput

System Model



High-quality

energy

Matter

System

Throughputs

Output

(intro environment)

Unsustainable

high-waste

economy

Low-quality

heat

energy

Waste

matter

and

pollution

Inputs

(from environment)


Low Throughput

System Model


High-quality

energy

Matter

Pollution

prevention

by

reducing

matter

throughput

Sustainable

low-waste

economy

Recycle

and

reuse

Pollution

control

by

cleaning

up some

pollutants

Matter

output

Low-quality

energy

(heat)

Waste

matter

and

pollution

Matter

Feedback

Energy Feedback

Inputs

(from environment)

System

Throughputs

Outputs

(from environment)


Easter Island

What are the statues and where are the trees? A case

Study in unsustainable growth practices. GURU IBESS/GURU/SYSTEMS & MODELS

Evaluating Models

Used when we can’t accurately measure the real event

Models are hard with the environment because there are so many interacting variables – but nothing else could do better

Allows us to predict likelihood of events

But…

They are approximations

They may yield very different results from each other or actual events

There are always unanticipated possibilities… GURU IBESS/GURU/SYSTEMS & MODELS

Anticipating Environmental

Surprises

Remember any action we take has multiple unforseen consequences

Discontinuities = Abrupt shifts occur in previously stable systems once a threshold is crossed

Synergistic interactions = 2 factors combine to produce greater effects than they do alone

Unpredictable or chaotic events = hurricanes, earthquakes, climate shifts

http://www.nhc.noaa.gov/archive/2008/FAY_graphics.shtml




What can we do?

Develop more complex

models for systems

Increase research on

environmental thresholds

for better predictive

power

Formulate possible

scenarios and solutions

ahead of time


Systems

Measurement

Data

Analysis

System

Modeling

System

Simulation

System

Optimization

Define objectives

Identify and inventory variables

Obtain baseline data on variables

Make statistical analysis of relationships among variables

Determine significant interactions

Construct mathematical model describing

interactions among variables

Run the model on a computer, with values

entered for different variables

Evaluate best ways to achieve objectives

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Other systems

examples


Uranium

100%

Electricity from Nuclear Power Plant

14%

Resistance

heating

(100%)

90%

Waste

heat Passive Solar

Sunlight

100%

Waste

heat

14%

Transmission

of electricity

(85%)

17%

Waste

heat

Power

plant

(31%)

54%

Waste

heat

Uranium processing

and transportation

(57%)

95%

Waste

heat

Uranium

mining

(95%)

Energy

Production


sun EARTH

Natural

Capital

Air; water,

land, soil,

biodiversity,

minerals,

raw materials,

energy

resources,

and dilution,

degradation,

and recycling

services

Economic

Systems

Production

Consumption

Heat

Depletion of

nonrenewable

resources

Degradation and

depletion of renewable

resources used faster

than replenished

Pollution and waste

from overloading

nature’s waste disposal

and recycling systems

Recycling and reuse

Economics

& Earth GURU IBESS/GURU/SYSTEMS & MODELS

Energy Inputs System Outputs

U.S.

economy

and

lifestyles

84%

8%

4%

4%

9%

7%

41%

43%

Nonrenewable fossil fuels

Nonrenewable nuclear

Hydropower, geothermal,

wind, solar

Biomass

Useful energy

Petrochemicals

Unavoidable energy

waste

Unnecessary energy

waste GURU IBESS/GURU/SYSTEMS & MODELS

Thank you

By

Guru


Education

2.systems and models new