dcV

dt

dcV

dt

Modeling Lecture 1. Modeling and Sustainability

CE4505 Surface Water Quality Engineering

CE4505 – Surface Water Quality Engineering

Sustainability

 In our every deliberation we must consider the impact of our decisions on the next seven generations.Iroquois Confederacy

http://www.interspecies.com/pages/7th_gen.htmlhttp://www.bathtram.org/tfb/tE04.htm

Meeting the needs of the present without compromising the ability of future generations to meet their own needs. World Commission on Environment and Development, 1987

CE4505 – Surface Water Quality Engineering

…a mathematical model is an idealized formulation that represents the response of a physical system to external stimuli.

dcV

dt

dcV

dt

Chapra 1997, p. 10

Modeling

CE4505 – Surface Water Quality Engineering

Toward Sustainability

1) a knowledge of the way a system works.

We might think of this as a research model.

2) a manner of predicting cause and effect.

We might think of this as a management model.

Decisions supporting a sustainable future require:

CE4505 – Surface Water Quality Engineering

Understanding the System

http://www.wordinfo.info/words/index/info/view_unit/1/?letter=B&spage=3

The Blind Men and the ElephantJohn Godfrey Saxe, 1816-1887

CE4505 – Surface Water Quality Engineering

It was six men of Indostan To learning much inclined,

Who went to see the Elephant (Though all of them were blind),

That each by observation Might satisfy his mind

The First approached the Elephant, And happening to fall

Against his broad and sturdy side, At once began to bawl:

“God bless me! but the Elephant Is very like a wall!”

The Second, feeling of the tusk, Cried, “Ho! what have we here

So very round and smooth and sharp? To me ’tis mighty clear

This wonder of an Elephant Is very like a spear!”

The Third approached the animal, And happening to take

The squirming trunk within his hands, Thus boldly up and spake:

“I see,” quoth he, “the Elephant Is very like a snake!”

To Better See the Elephant …

The Fourth reached out an eager hand, And felt about the knee.

“What most this wondrous beast is like Is mighty plain,” quoth he;

“ ‘Tis clear enough the Elephant Is very like a tree!”

The Fifth, who chanced to touch the ear, Said: “E’en the blindest man

Can tell what this resembles most; Deny the fact who can

This marvel of an Elephant Is very like a fan!”

The Sixth no sooner had begun About the beast to grope,

Than, seizing on the swinging tail That fell within his scope,

“I see,” quoth he, “the Elephant Is very like a rope!”

And so these men of Indostan Disputed loud and long,

Each in his own opinion Exceeding stiff and strong,

Though each was partly in the right, And all were in the wrong!

So oft in theologic wars, The disputants, I ween,

Rail on in utter ignorance Of what each other mean,

And prate about an Elephant Not one of them has seen!

CE4505 – Surface Water Quality Engineering

To provide a better understanding of the mechanisms and interactions that give rise to various types of water quality behavior, such understanding to be sharpened by the formulation and testing of hypotheses of the cause-effect relationships between residual inputs and resulting water quality.

(Thomann and Mueller 1987)

Research Models

CE4505 – Surface Water Quality Engineering

FieldObservations

MathematicalModel

ProcessStudies

ConceptualFramework

To Validate our Understanding of System Response

Why model? The research perspective –

CE4505 – Surface Water Quality Engineering

Predicting Cause and Effect

CE4505 – Surface Water Quality Engineering

Cause & Effect: firing a projectile

by Trial and ErrorCE4505 – Surface Water Quality Engineering

Cause and Effect: achieving sustainability

by Build and MeasureCE4505 – Surface Water Quality Engineering

underdesign -

…the environmental engineering equivalent of building a bridge that falls down.

www.civil.columbia.edu/ce4210/bridgecollapse.html

(Thomann and Mueller 1987, p. ix)

Undesirable Outcomes

CE4505 – Surface Water Quality Engineering

overdesign -

…the environmental engineering equivalent of building a bridge to nowhere.

http://www.zen39641.zen.co.uk/ps/

(Thomann and Mueller 1987, p. ix)

Undesirable Outcomes

CE4505 – Surface Water Quality Engineering

Cause and Effect: firing a projectile

20 sin 2

vR

g

by Applying a Model

angle

dis

tan

ce

CE4505 – Surface Water Quality Engineering

Linking …

Action and ReactionPerturbation and ResponseCause and Effect

by Applying a Model

Cause and Effect: achieving sustainability

CE4505 – Surface Water Quality Engineering

Specify water use

Establish water quality criteria

Determine cause and effect

Identified engineered alternatives

Conduct cost-benefit analysis

Evaluate socioeconomic impact

A Water Quality Management Plan

CE4505 – Surface Water Quality Engineering

To provide a more rational basis for making water quality control decisions, such a basis to include a defensible, credible, predictive framework, within the larger framework of cost-benefit analysis.

(Thomann and Mueller 1987)

Why Model?

CE4505 – Surface Water Quality Engineering

Why model?

CE4505 – Surface Water Quality Engineering

Guidance for Management Actions

Quantificationof

Loads

Characterizationof

Fate & Transport

Mathematical Model

Engineered Solutions

Model Implementations

CE4505 – Surface Water Quality Engineering

, , ,c f W physics chemistry biology

1c W

a

Define “a” as an assimilation factor, L3·T-1

Simulation Mode

W a c Design Mode 1 – assimilative capacity

Wa

c Design Mode 2 – environmental modification

(Chapra 1997, Figure 1.1)

Water and Wastewater in an Urban Setting

CE4505 – Surface Water Quality Engineering

(Chapra 1997, Figure 1.2)

The Water Quality Management Process

CE4505 – Surface Water Quality Engineering

CE5504 – Surface Water Quality Modeling

• universities/institutes (UFI)

• government (LLRS)

• consulting (LTI)

EPA Large Lakes Research StationGrosse Ile, Michigan

Limno Tech, Inc. Ann Arbor, Michigan

Upstate Freshwater InstituteSyracuse, New York

Opportunities