Modeling Lakes? Center for Watershed Science & Education UW- - - PowerPoint PPT Presentation

SLIDE 1

Modeling Lakes?

Center for Watershed Science & Education UW- Stevens Point

Lake Leaders 2010

SLIDE 2

What’s a model

One definition: A mathematical description to help visualize something

SLIDE 3

What’s a model

One definition: A mathematical description to help visualize something

SLIDE 4

80 lb Phosphorus/yr 325 million gallons/year

A model for the phosphorus concentration in a lake Amount of Phosphorus

= ------------------------

Amount of Water

SLIDE 5

80 lb Phosphorus/yr 325 million gallons/year

= 80 lb/ 325 million gallons =

SLIDE 6

80 lb Phosphorus/yr 325 million gallons/year

= 80 lb/ 3 billion lbs water=

SLIDE 7

80 lb Phosphorus/yr 325 million gallons/year

= 80 lb/ 3 billion lbs water= 27 ppb

SLIDE 8

Why Model?

• Groundwater flow– where water is coming

from?

• Lake concentration —what if we change the

amount added?

• Watershed modeling– can watershed

changes help and by how much?

• In-Lake Restoration – “experiment” with

treatment, diversions etc.

SLIDE 9

Rule #1

“All models are wrong but some are useful”

George Box

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22” 32” 10”

Watershed Models

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Land is a concentrated nutrient source

40 microgram /liter 300,000 microgram /liter

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Simple Model: Assign annual transfer rate to different land uses Complex Model: Simulate every storm, interaction with ground, conveyance to channel, transport to lake

SLIDE 13

Rule #2

“Make everything as simple as possible, but not simpler”

• A. Einstein

SLIDE 14

Zooplankton Bacteria

WATER

Algae FISH Water Quality

N U T R I E N T S

Lake Models

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Phosphorus Concentration (mg/l) Productivity 10 Low (Oligotrophic) 10-20 Medium (Mesotrophic) Greater than 20 High (Eutrophic)

Lake Models

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Annual Phosphorus Input Annual Water Input Annual Phosphorus Settling

Simpler Models…

• -completely mixed
• - steady with time

Complex Models…

• -segments in lake
• -vary with time
• -biology!

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Phosphorus Concentration Algae Concentration

Lake Response Model?

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Application to Portage County

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Median Nitrate

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 B e a r J a c q u e l i n e S e v e r s

• n

S u n s e t W

• l

f B

• e

l t e r S

• u

t h T w i n L i

• n

s O n l a n d S k u n k T h

• m

a s J

• n

a s L i m e H e l e n R i n e h a r t P i c k e r e l E m i l y A d a m s C

• l

l i n s T r e e F

• u

n t a i n R

• s

h

• l

t J

• r

d a n B e n t l y P

• n

d M c D i l l S p r i n g A m h e r s t M i l l P

• n

d E b e r t S p r i n g v i l l e NO2+NO3-N (mg/L)

Median Chloride

0.00 5.00 10.00 15.00 20.00 25.00 Bear Jacqueline South Twin Wolf Severson Sunset Thomas Lions Skunk Fountain Onland Spring Collins Boelter Adams Emily Rinehart Pickerel Amherst Mill Pond Ebert Tree Bently Pond Rosholt Jordan Lime Jonas McDill Springville Helen Chloide (mg/L)

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Median Total Phosphorus

10 20 30 40 50 60 70 A d a m s O n l a n d J

• n

a s E b e r t E m i l y L i

• n

s R i n e h a r t F

• u

n t a i n S k u n k S u n s e t P i c k e r e l S e v e r s

• n

T h

• m

a s W

• l

f B e a r H e l e n J a c q u e l i n e T r e e C

• l

l i n s L i m e S

• u

t h T w i n S p r i n g v i l l e M c D i l l A m h e r s t M i l l P

• n

d J

• r

d a n R

• s

h

• l

t S p r i n g B e n t l y P

• n

d B

• e

l t e r TP (μg/L)

Median Chlorophyll A

2 4 6 8 10 12 14 16 18 20 T h

• m

a s O n l a n d A m h e r s t M i l l P

• n

d R i n e h a r t E b e r t F

• u

n t a i n J

• n

a s P i c k e r e l E m i l y S u n s e t A d a m s L i

• n

s W

• l

f S e v e r s

• n

S k u n k J

• r

d a n H e l e n B e n t l y P

• n

d J a c q u e l i n e B e a r C

• l

l i n s T r e e R

• s

h

• l

t L i m e S p r i n g M c D i l l S

• u

t h T w i n S p r i n g v i l l e B

• e

l t e r Chlor a (mg/L)

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Average Total Hardness in Portage Co. Lakes 25 50 75 100 125 150 175 200 225 250 Jacqueline Soulth Twin Boelter Collins Bear Joanis Thomas Onland Pickerel Lions Sunset Emily Helen Wolf Mcdill Pond Rosholt Jordan Pond Tree Skunk Lime Severson Fountain Bently Ebert Rinehart Springville Spring Amherst Adams mg/L as CaCO 3

Median pH

5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00 South Twin Boelter Jacqueline Bear Collins Severson Bently Pond Rosholt Lime Spring Adams Ebert Jordan Amherst Mill Pond Sunset Tree Fountain McDill Skunk Jonas Springville Rinehart Lions Thomas Onland Emily Helen Wolf Pickerel pH

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Portage County Model

• Groundwater Inputs (based on groundwater

modeling)

• Surface watershed inputs (two categories:

developed and undeveloped)

• In-lake – mixed and steady-state

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Groundwater Flow System

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Used Actual Lake Data to Determine Watershed Export Coefficients

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Current Condition

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Questions