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

Modeling Lakes? Center for Watershed Science & Education UW- Stevens Point Lake Leaders 2010

What’s a model One definition: A mathematical description to help visualize something

What’s a model One definition: A mathematical description to help visualize something

A model for 80 lb the Phosphorus/yr phosphorus concentration in a lake 325 million gallons/year Amount of Phosphorus = ------------------------ Amount of Water

80 lb Phosphorus/yr 325 million gallons/year = 80 lb/ 325 million gallons =

80 lb Phosphorus/yr 325 million gallons/year = 80 lb/ 3 billion lbs water=

80 lb Phosphorus/yr 325 million gallons/year = 80 lb/ 3 billion lbs water= 27 ppb

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.

Rule #1 “All models are wrong but some are useful” George Box

32” Watershed Models 10” 22”

300,000 40 microgram microgram /liter /liter Land is a concentrated nutrient source

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

Rule #2 “Make everything as simple as possible, but not simpler” A. Einstein

Lake Models Water FISH Quality Zooplankton Algae Bacteria N U T R I E N T S WATER

Lake Models Phosphorus Concentration Productivity ( m g/l) 10 Low (Oligotrophic) 10-20 Medium (Mesotrophic) Greater than 20 High (Eutrophic)

Annual Simpler Models… Phosphorus Input --completely mixed -- steady with time Annual Water Input Annual Phosphorus Settling Complex Models… --segments in lake --vary with time --biology!

Lake Response Model? Phosphorus Algae Concentration Concentration

Application to Portage County

Median Nitrate 7.00 6.00 NO 2 +NO 3 -N (mg/L) 5.00 4.00 3.00 2.00 1.00 0.00 e n n d n t e n e r t f r s k s s e l s s n t d l g t l r y l l d a o e e e r l n o i n n a a e a m e i o a i n w n m l n a n D e l e s t r i n i i s W n l m r d v l o a u m h e i h o i b l n e T e a l T t r o B e r o i l r c i l k L e n s p g e L n H k E o o P P E u u o o d M S J c u o S n v h n C S B O h A J q o R y e i i l i t T R P l r c u l F i p S t M a o n S J S e t B s r e h m A Median Chloride 25.00 20.00 Chloide (mg/L) 15.00 10.00 5.00 0.00 Severson Bear Jacqueline South Twin Thomas Lions Fountain Onland Spring Rinehart Ebert Tree Rosholt Jordan Jonas Springville Helen Wolf Sunset Skunk Collins Boelter Adams Emily Pickerel Bently Pond Lime McDill Amherst Mill Pond

Median Total Phosphorus 70 60 50 TP (μg/L) 40 30 20 10 0 d t n n e e n e n s s t s n k t l s f r s e l t g d r y r l l d r e e o a l e n a n a i a o e n e i l i a o n m e l n n m w l D n i a r e n n m s s W l i r i d t a b o h u e m i v h i o l t e l l o r a n r B e T i T c e l o i e n k l L g r s p E k e H o P d n E L u o M P o o J u u o n S c h n S O v h C J A S q B o i i l R y i e t r R P T l F c u p i l S M t a o n S J S e t B s r e h m A Median Chlorophyll A 20 18 16 Chlor a (mg/L) 14 12 10 8 6 4 2 0 n n e s d t t n s s f n e r e t g n r l y t s k d s e l d r r e e l o a l l e n i a o a e n e i i l a a e l m n n n n o m n l n a r i D w s s e i t m a h n e m o W u d l i r h i v o b t e o l i r l n a r e B l T i c T e n o r l s p l e E k i k P L g o n P E u d L e o H o M o u n u J c S o S n O v C h h S A J B o i y q R i l i e t T l R P r l c u i F p M S t n a o S e J S t B s r e h m A

Average Total Hardness in Portage Co. Lakes 250 225 mg/L as CaCO 3 200 175 150 125 100 75 50 25 0 Pickerel Mcdill Pond Lime Jacqueline Collins Emily Helen Rosholt Jordan Pond Tree Skunk Fountain Ebert Rinehart Springville Soulth Twin Boelter Bear Thomas Onland Lions Wolf Bently Spring Adams Joanis Sunset Severson Amherst Median pH 10.00 9.50 9.00 8.50 8.00 pH 7.50 7.00 6.50 6.00 5.50 5.00 Severson Jordan Springville South Twin Boelter Jacqueline Bear Collins Rosholt Lime Spring Ebert Tree Fountain Jonas Rinehart Lions Thomas Onland Helen Wolf Bently Pond Adams Sunset McDill Skunk Emily Pickerel Amherst Mill Pond

• Groundwater Inputs (based on groundwater modeling) • Surface watershed inputs (two categories: developed and undeveloped) • In-lake – mixed and steady-state Portage County Model

Groundwater Flow System

Used Actual Lake Data to Determine Watershed Export Coefficients

Current Condition

Questions