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Airborne Laser Scanning for Airborne Laser Scanning for Riverbank Erosion Assessment Riverbank Erosion Assessment- Riverbank Erosion Assessment Riverbank Erosion Assessment Implications for Water Quality Implications for Water Quality Satish Gupta Professor Department of Soil, Water, & Climate University of Minnesota, St. Paul, MN 26 August 2011 Metropolitan Water Reclamation District of Greater Chicago Cicero, IL Lake Pepin Sedimentation Lake Pepin Sedimentation Concern Drainage Higher sedimentation Concern Cultivation Higher sedimentation rates in recent years Engstrom and Almendinger, 2000 Aerial View of Lake Pepin Aerial View of Lake Pepin Aerial View of Lake Pepin Aerial View of Lake Pepin 34 km long, 2-3 km wide, Lake Area,103 km 2 water residence time about 17 weeks residence time about 1 7 weeks St. Croix Watershed Research Station Fact Sheet 2000-02 Study Area 25% Flow 50% Flow 25% Fl 25% Flow 75% Sediment St. Croix Watershed Research Station Fact Sheet 2000-02 Some Statistics Some Statistics 33% of the land in MRB is <2% slope 74% of the land in MRB is <6% slope Minnesota River Basin (MRB) MRB 74% of the land in MRB is <6% slope Blue Earth River Basin (BERB) MRB 54% of the land in the BERB is <2% slope 93% of the land in the BERB is <6% However, the Blue Earth River delivers 46% of the flow and Mankato 55% of all sediment to the Minnesota River at Mankato. BERB Aerial View of Potholes f after Rain

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Page 1: Airborne Laser Scanning for Riverbank Erosion ... · 8/26/2011  · Airborne Laser Scanning for Riverbank Erosion AssessmentRiverbank Erosion Assessment-Implications for Water Quality

Airborne Laser Scanning for Airborne Laser Scanning for Riverbank Erosion AssessmentRiverbank Erosion Assessment--Riverbank Erosion AssessmentRiverbank Erosion Assessment

Implications for Water QualityImplications for Water Quality

Satish GuptaProfessor

Department of Soil, Water, & ClimateUniversity of Minnesota, y ,

St. Paul, MN

26 August 2011Metropolitan Water Reclamation District of Greater Chicago

Cicero, IL

Lake Pepin SedimentationLake Pepin Sedimentation

ConcernDrainage

Higher sedimentation

Concern

Cultivation

Higher sedimentationrates in recent years

Engstrom and Almendinger, 2000

Aerial View of Lake PepinAerial View of Lake PepinAerial View of Lake Pepin Aerial View of Lake Pepin 34 km long, 2-3 km wide, Lake Area,103 km2 water

residence time about 1–7 weeksresidence time about 1 7 weeks

St. Croix Watershed Research Station Fact Sheet 2000-02

Study Area

25% Flow50% Flow

25% Fl25% Flow75% Sediment

St. Croix Watershed Research Station Fact Sheet 2000-02

Some StatisticsSome Statistics

33% of the land in MRB is <2% slope

74% of the land in MRB is <6% slope

Minnesota River Basin (MRB)

MRB 74% of the land in MRB is <6% slope

Blue Earth River Basin (BERB)

MRB

54% of the land in the BERB is <2% slope

93% of the land in the BERB is <6%

However, the Blue Earth River delivers 46% of the flow and

Mankato

55% of all sediment to the Minnesota River at Mankato.

BERB

Aerial View of Potholesfafter Rain

Page 2: Airborne Laser Scanning for Riverbank Erosion ... · 8/26/2011  · Airborne Laser Scanning for Riverbank Erosion AssessmentRiverbank Erosion Assessment-Implications for Water Quality

Removing Excess WaterSurface Inlet

Removing Excess Water Sediment Sources in the Sediment Sources in the Minnesota River BasinMinnesota River Basin

Flat Fields

Sediment Sources in the Sediment Sources in the Minnesota River BasinMinnesota River Basin

River Banks

Peggy K, Fall 2010

Potential Sources of SedimentPotential Sources of Sediment

Erodingriverriverbanks

Flat upland landscapePerson for scale

Laser Scanningg

Blue Earth River

David Thoma, 2003

April 2005 April 2009

∆DEM, Ft-28 - -10

-10 - -5

-5 - -2

-2 - 2

2 - 5

5 - 9

9 - 10

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Sand 43.7 %Silt 25.0 % Net Volume Change 3,145 m3 /

year

Change DetectionSoil Analysis

Clay 31.3%Fines (Silt&Clay) 56.3 %

Net Soil Loss(Mass Wasting)

5, 724 Mg / year

Fine Sediment Loss 3, 223 Mg / Bulk Density 1.82 Mg m-3

Fine Sediment Loss year

LiDARLiDAR Study AreaStudy AreaLiDARLiDAR Study AreaStudy Area

LiDAR= Light Detection and Ranging

Volume Change of River Valleys Volume Change of River Valleys From Bank ErosionFrom Bank Erosion

600000

800000

nge,

m3

Total Volume Loss=1.71 million m3

400000

600000

ume

Cha

n

200000Vol

0

River

Volume ChangeVolume ChangeBluff (>3m) vs Bank (<3m)Bluff (>3m) vs Bank (<3m)

100%

Bluff (>3m) vs. Bank (<3m)Bluff (>3m) vs. Bank (<3m)Bluffs

80% % of Length along River 33%% of Area 63%

60%

Bluff

75%40% Bank

25%

0%

20%

0%

All Rivers

Characteristics of Parent Characteristics of Parent MaterialsMaterials

Parent Material

Silt+Clay%

Bulk DensityMg m-3

Soluble Pmg kg-1

Total Pmg kg-1g g g g g

Till 56.3 1.82 0.46 408.8Lacustrine 67.3 1.48 0.74 556.2Alluvium 52 5 1 49 0 73 558 6Alluvium 52.5 1.49 0.73 558.6

Annual Measured LossesAnnual Measured LossesAnnual Measured LossesAnnual Measured Losses

Rivers SedimentMg r 1

Soluble Pkg r 1

Total PMg r 1Mg yr-1 kg yr-1 Mg yr-1

Blue Earth River 216,145 191.1 166.2Le Sueur River 132,824 117.5 102.1

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Sediment Contribution from Bank Sediment Contribution from Bank CCErosion in Blue Earth CountyErosion in Blue Earth County

60

sses

, % Till

Lacustrine

40

men

t Los

Alluvium48 to 63% 61 to 79%

20

ne S

edim

0Fi

River

Soluble P Contribution from Bank Soluble P Contribution from Bank CCErosion in Blue Earth CountyErosion in Blue Earth County

0.2

s, %

Till

L t i0 16 t 0 20% 0 13 t 0 17%

0.1

P Lo

sses Lacustrine

Alluvium

0.16 to 0.20% 0.13 to 0.17%

0

Solu

ble

0

River

Total P Contribution from Bank Total P Contribution from Bank CCErosion in Blue Earth CountyErosion in Blue Earth County

40

%

Till

Lacustrine40 to 45% 44 to 49%

20Loss

es, % Lacustrine

Alluvium

Tota

l P

0

River

FindingsFindingsFindingsFindings

MultiMulti--temporaltemporal lidarlidar datasets are useful fordatasets are useful forMultiMulti temporal temporal lidarlidar datasets are useful for datasets are useful for estimating bank erosion and associated P estimating bank erosion and associated P contributions over large scales and forcontributions over large scales and forcontributions over large scales, and for contributions over large scales, and for river banks that are not readily accessible river banks that are not readily accessible for conventional surveying equipmentfor conventional surveying equipmentfor conventional surveying equipment.for conventional surveying equipment.

Thi th d h d t th t itThi th d h d t th t itThis method has an advantage that it can This method has an advantage that it can help identify banks that are a major source help identify banks that are a major source f di t i i i tf di t i i i tof sediments in a given river system. of sediments in a given river system.

Mechanisms of Bank SloughingMechanisms of Bank Sloughing3 December 20093 December 2009

HWY 169 Mankato

Soil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow Water

10:20 AM

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Soil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow Water

10:21 AM

Soil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow Water

10:22 AM

Soil Slumping in Shallow WaterSoil Slumping in Shallow Waterp gp g

10:24 AM

Soil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow Water

10:27 AM

Soil Slumping in Shallow WaterSoil Slumping in Shallow Waterp gp g

10:28 AM

Soil Slumping in Shallow WaterSoil Slumping in Shallow Waterp gp g

10:30 AM

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Soil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow WaterSoil Slumping in Shallow Water

10:44 AM

Behind Leroy’s House Behind Leroy’s House March 19, 2009March 19, 2009

Seepage during winter

Meg and Richard’s BankMeg and Richard’s BankVernon CenterVernon Center

Le Sueur RiverLe Sueur RiverMarch 2010 April 2011

Scott Salsbury

Kevin’s Bank (2011)Kevin’s Bank (2011)Kevin s Bank (2011)Kevin s Bank (2011) Seepage and Collateral DamageSeepage and Collateral Damage

Seepage

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Pore Water Pressure SlumpingPore Water Pressure Slumping

PiezometerPiezometer Tensiometer

Pore Water EffectEagle Lake

Thiesen Bank CCapillarity and Failure

Capillary action and sloughing

Richard and Meg’s Bank27 May 2010

Richard and Meg’s Bank 28 June 2010

Richard and Meg’s Bank 28 June 2010

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Richard and Meg’s Bank 5 August 2010

Present Day River on 1938 Photograph

Slumping Bank at Vernon Slumping Bank at Vernon CenterCenter

This bank has moved 300 ft in 40 years

Slumping Bank at Vernon Slumping Bank at Vernon Center, 2011Center, 2011

Slump at the top

Slumping Bank at Vernon Slumping Bank at Vernon Center, 2011Center, 2011

Accumulation at the bottom

FindingsFindingsBanks are sloughing from the top and has

nothing to do with river levels This sloughingnothing to do with river levels. This sloughing appears to be due to seepage.

Bank sloughing is also occurring due to catastrophic events and channel migration.

Agriculture is also contributing some sediments to the rivers through surface inlets.g

Important factors are soil strength and availability of wateravailability of water

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Minnesota River BasinMinnesota River BasinMinnesota River BasinMinnesota River Basin Historic Conditions of the RiversHistoric Conditions of the Rivers

22 September 1835

G.W. Featherstonhaugh, 1847

Historic Conditions of the RiversHistoric Conditions of the Rivers

September 22, 1835

G.W. Featherstonhaugh, 1847

Similar to USGS measurements (Payne, 1994)

Historic Conditions of the Rivers

“Still, the river itself did not impress some visitors. A “Still, the river itself did not impress some visitors. A , p, pprejudiced traveler from the St. Croix, the handsome prejudiced traveler from the St. Croix, the handsome

stream that forms Wisconsin's western boundary, put down stream that forms Wisconsin's western boundary, put down his rather uncharitable verdict in his diary: “his rather uncharitable verdict in his diary: “The Minnesota The Minnesota

RiRi ” h t i” h t i 18561856 ““i di t littl ki di t littl k ””RiverRiver,” he wrote in ,” he wrote in 18561856, “, “is a dirty little creekis a dirty little creek.”.”

St. Croix

Mississippi after its joins the Minnesota River Jones, Evan (1962), The Minnesota: Forgotten River.Jones, Evan (1962), The Minnesota: Forgotten River.

Minnesota River Turbidity and H d h t M k t 1905Hydrograph at Mankato, 1905

Turbidity=400 ppm Ordinarily Turbidity 10-40 ppm10 40 ppm

Spring Flush Turbidity ft i d t

Gage Ht=10 ftoften increased to

600-800 ppm

Dole and Wesbrook, 1907

Turbidity Variations, Turbidity Variations, yy19061906--19071907

Minnesota River vs. Mississippi River

400

200

300

400

ty, p

pm

Shakopee

PPT 1906=29.0” 1907=22.7”

0

100

200

Turb

idit p

Minneapolis

0250 350 450 550 650

Day

T

Day

Dole, R.B. (1909)

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St. Croix Joining Mississippi2 June 2004, High Flow

St CroixSt. Croix

Mississippi after its joins the Minnesota River

David Morrison, MPCA

MississippiMississippi--St. Croix Rivers St. Croix Rivers ppppConfluenceConfluence

22 September 1937 11 July 1938p 11 July 1938

MississippiMississippi--St. Croix Rivers St. Croix Rivers ss ss ppss ss pp St C o e sSt C o e sConfluenceConfluence

1 June 1957 15 July 196428 October 1949

St. Croix Joining Mississippi1 May 1960

Minnesota Museum of History

Minnesota at the Confluence with Mississippi

10 May 195730 June 1937 25 June 1940

Blue Earth Joining MinnesotaBlue Earth Joining Minnesota

MN DNR-MHAPO-1938 USDA-FSA 2002 Photo Scott Salsbury

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FindingFindingFindingFinding

The Minnesota River and its tributariesThe Minnesota River and its tributariesThe Minnesota River and its tributaries The Minnesota River and its tributaries have been muddy or turbid since before have been muddy or turbid since before prepre--settlement timessettlement timesprepre settlement times.settlement times.

Lake Pepin SedimentationLake Pepin Sedimentation

1850- Population 6,077 Primitive agriculture-Earlier plows were

wooden plows with metal tips

Cultivation

Sticky soils-shallow cultivation Flat lands-not enough capacity to

transport Good cover crop-Small grains wild hay Good cover crop-Small grains, wild hay,

flax, some corn

Engstrom and Almendinger, 2000

Lake Pepin SedimentationLake Pepin Sedimentation

Limited Drainage-surface inlet to Depressions only

Drainage

Depressions only 1930s-Drought and depression 1940-World war II, many men were gone Corn in 3 to 5 year rotations-limited soil

ierosion 1950-Drainage picked up, clay and

cement tiles 1970-Plastic tile line was available 1970 Plastic tile line was available

Engstrom and Almendinger, 2000

Confluence of the Minnesota Confluence of the Minnesota and the Mississippi Riversand the Mississippi Rivers

Star Tribune Image Spring 2011 USDA Image 30 June 1937

BackgroundBackground

SedimentRiver Banks Sediment production has not

changed dramatically sinceSediment ProductionFields

Ravines

changed dramatically since earlier times. A majority of them are coming from river bankswhich mainly depends

i it ti

Sediment Transport

upon precipitation.

There are some sediment coming from agricultural fields

Transport thru surface inlets

Sediment Load to Lake Pepinto Lake Pepin

Minnesota River Watershed, Minnesota River Watershed, P t d P tP t d P tPast and PresentPast and Present

Changes in the Basin

Prior to 1850 Presentthe Basin

Less basin storage

Less meandering

Dredging, deepening & leveesdeepening & levees

More precipitationMN River

More impervious surfaces

Locks and dams

MN River

Lake Pepin

Moving deltaLocks and dams

Smaller Lake Pepin

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Straightening of Minnesota Straightening of Minnesota g gg gRiver ChannelRiver Channel

10 May 1957 August 1980

Channel was straightened at Fort Snelling in 1964at Fort Snelling in 1964.

Area under Impervious SurfacesArea under Impervious SurfacesYear MN River

BasinMankatoTo Fort

Area under Impervious SurfacesArea under Impervious Surfaces

SnellingPercent

2000 6 13

Y MN Ri B i

2000 6 13

1990 4 8

Year MN River Basin in MetroPercent

2002 301998 271991 241986 20

Bauer, Loffelholz, and Wilson (2007)

DredgingDredging

18931893--1943,1943, a sandbar formed everya sandbar formed every18931893 1943,1943, a sandbar formed every a sandbar formed every spring, leaving only 18 inches of water at spring, leaving only 18 inches of water at the entrance but 6 feet deep channel for the entrance but 6 feet deep channel for pp24 miles. 24 miles.

World War IIWorld War II--Cargill obtained a contract Cargill obtained a contract from the US Navy to build oceanfrom the US Navy to build ocean--going going yy g gg gtankers and towboats. They picked tankers and towboats. They picked Savage to build naval ships. Savage to build naval ships.

Merritt, Raymond H. 1979. Creativity, Conflict, & Controversy: A History of the St. Paul District. U.S. Army Corps of Engineers.U.S. Army Corps, 2010.

Launching the Chehalis at Launching the Chehalis at Port Cargill, Savage Port Cargill, Savage

Minnesota Historical SocietyHE5.25p2416 April 1944

Levee at MankatoLevee at MankatoLevee at MankatoLevee at Mankato

Scott Salsbury

Mankato 1951 FloodsMankato 1951 FloodsMankato, 1951 FloodsMankato, 1951 Floods

Floods188119081908191619511965

North Mankato aerial photo.Tree-lined street is Belgrade Avenue.

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FindingsFindingsFindingsFindings

Dredging opened up the Minnesota RiverDredging opened up the Minnesota RiverDredging opened up the Minnesota River Dredging opened up the Minnesota River to down stream transport of sediments.to down stream transport of sediments.

Levees eliminated flood plain interactions Levees eliminated flood plain interactions d f i t d di td f i t d di tand are forcing more water and sediments and are forcing more water and sediments

to down stream locations including Lake to down stream locations including Lake P iP iPepin.Pepin.

Climate and Flow IssuesClimate and Flow IssuesClimate and Flow IssuesClimate and Flow IssuesWhy is more flow in rivers?Why is more flow in rivers?

Wh are the ri ers ider?Wh are the ri ers ider?Why are the rivers wider?Why are the rivers wider?

Why are river flows nonWhy are river flows non--linear?linear?

Why is flow at Jordan doubled?Why is flow at Jordan doubled?yy

Trend In PrecipitationTrend In PrecipitationSouth Central MinnesotaSouth Central Minnesota

1940 19752010

NCDC, http://www.southernclimate.org/products/trends.php

DNR Major Watersheds12 C Wi

j12 Crow Wing14 Long Prairie R 16 Sauk River17 Elk River

36 Snake River39 Cannon River43 R t Ri21 Rum River

22 Whetstone23 Pomme de

Terre

43 Root River48 Cedar River60 Wild Rice R63 Red River Terre

24 Lac qui Parle26 Chippewa R.

63 ed eCrookston63 Red River Goodridge65 Thief River27 Redwood R.

29 Cottonwood R.30 Blue Earth R

65 Thief River Falls66 Clearwater R71 Roseau R 30 Blue Earth R.

31 Watonwan R.32 Le Sueur R.18 Middle Fork R

Ross76 Little Fork R.77 Big Fork R

18 North Fork Crow R35 Kettle River

Minnesota River Basin (Blue Earth, Le Sueur, Cottonwood, Redwood)

800

600

800Total N=140 165PPT>1000 n=2 8

y = 3E-06x2.6793

R² = 0.496400w

, mm

Blue Earth <1975

y = 9E-07x2.7974

200

Flo Blue Earth >1976

Power (Blue Earth <1975)

Power (Blue Earth >1976)

y 9E 07xR² = 0.3852

00 500 1000 1500

PPT,mm

South East Minnesota(Cannon, Cedar, Root)

600

800Total N=123 69PPT>1000 n=7 7

y = 0.0021x1.7298

R² = 0.4597

400

600

w, m

m SE Minnesota <1975

SE Minensota >1976

y = 0 0166x1 3731

200

Flow Power (SE Minnesota <1975)

Power (SE Minensota >1976)

y = 0.0166x1.3731

R² = 0.30560

0 500 1000 1500

PPT,mm

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Upper Mississippi Riverpp pp(Middle Fork Crow, Crow R, Long Prairie, Rum, Crow Wing, Sauk, Elk)

600

800Total N=202 202PPT>900 n=5 10

y = 0.0167x1.3743

R² = 0.28400

600

w, m

m

Upper Miss <1975

y = 1E 04x2 122200

Flow

pp

Upper Miss>1976

Power (Upper Miss <1975)

Power (Upper Miss>1976)

y = 1E-04x2.122

R² = 0.26

00 500 1000 15000 500 1000 1500

PPT,mm

FindingsFindingsFindingsFindingsIncreased precipitation leads to nonIncreased precipitation leads to non--linearlinearIncreased precipitation leads to nonIncreased precipitation leads to non linear linear

increase in runoff and river flows.increase in runoff and river flows.For a given level of annual precipitationFor a given level of annual precipitationFor a given level of annual precipitation, For a given level of annual precipitation,

there is no difference in river flows for the there is no difference in river flows for the period prior to 1975 and after 1976 forperiod prior to 1975 and after 1976 forperiod prior to 1975 and after 1976 for period prior to 1975 and after 1976 for HUC 8 level watersheds.HUC 8 level watersheds.

This would suggest that tile line effect areThis would suggest that tile line effect areThis would suggest that tile line effect are This would suggest that tile line effect are not on the quantity of water leaving the not on the quantity of water leaving the landscapelandscapelandscape. landscape.

FindingsFindingsFindingsFindings

Tiling effect could be on timing of flow andTiling effect could be on timing of flow andTiling effect could be on timing of flow and Tiling effect could be on timing of flow and also at smaller scale (smaller watersheds also at smaller scale (smaller watersheds or daily weekly time scale)or daily weekly time scale)or daily, weekly time scale).or daily, weekly time scale).

Fl i Mi t Ri t J dFl i Mi t Ri t J dFlows in Minnesota River at Jordan are Flows in Minnesota River at Jordan are higher due to both increased precipitations higher due to both increased precipitations i th ll f li th ll f lin the area as well as presence of levees in the area as well as presence of levees upstream (lack of flood plain interactions).upstream (lack of flood plain interactions).

Presence of Delta at the Mouth of Presence of Delta at the Mouth of Lake PepinLake Pepin

Delta

St. Croix Watershed Research Station Fact Sheet 2000-02

ConcernsConcernsSedimentation Rate in Lake Pepin Transect I and II

Engstrom and Almendinger, 2000

Delta Effect on VolumeDelta Effect on Volume

t1

Sediment Delivered

t2

Sediment Delivered

t3

Sediment Delivered

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Various Forms of P in Lake Various Forms of P in Lake Pepin SedimentsPepin Sediments

Prior to 1800 Total P=0.6 to 0.8 mg/g=600-800 mg/kg

1960-1980 Total P=<1.8 mg/g=1800 mg/kg

Engstrom et al., 2009

Total, Soluble, and Enriched P in Bank Total, Soluble, and Enriched P in Bank Materials Under Natural ConditionsMaterials Under Natural Conditions

Sample Parent M Total P mg/kg

Soluble Pmg/kg

Sand%

Silt%

Clay%

Enrichment ratio

EnrichedP, mg/kg

100 Till 397 0.20 25.5 28.0 46.5 1.34 533

106 Till 462 0.18 41.7 27.5 30.9 1.71 790

113 Lacustrine 424 0 18 17 1 28 0 54 9 1 2 511113 Lacustrine 424 0.18 17.1 28.0 54.9 1.2 511

128 Alluvium 537 0.22 17.0 54.0 29.0 1.20 647

Prior to 1800 Total P=0.6 to 0.8 mg/g=600-800 mg/kg

Engstrom et al. 2009

1960-1980 Total P=<1.8 mg/g=1800 mg/kg

P Adsorption IsothermP Adsorption IsothermP Adsorption IsothermP Adsorption Isotherm

160

200

kg

Sample # 100

120

on, m

g/k

y = -1.4343x2 + 29.161x - 0.8242R² = 0 996140

80

So

rptio

R² = 0.9961

00 2 4 6 8 10

-40Soluble P Concentration, mg/L

P Adsorption IsothermP Adsorption IsothermP Adsorption IsothermP Adsorption Isotherm

550

600, m

g/kgSample # 100

500

550

cent

ratio

n

y = -1.5059x2 + 29.991x + 394.63R² = 0.9964

400

450

otal

P C

onc

3500 2 4 6 8 10

To

Soluble P Concentration, mg/L, g

Total, Soluble, and Enriched P in BankTotal, Soluble, and Enriched P in BankTotal, Soluble, and Enriched P in Bank Total, Soluble, and Enriched P in Bank Materials after AdsorptionMaterials after Adsorption

Sample Parent M Natural Total P mg/kg

Total P after Adsorption at 10 mg/L Soluble P

/k

Enrichment ratio

Natural EnrichedP, mg/kg

Enriched Pafter

Adsorptionmg/kg

100 Till 397 571 1.34 533 765

106 Till 462 593 1 71 790 1 014106 Till 462 593 1.71 790 1,014

113 Lacustrine 424 549 1.2 511 659

128 Alluvium 537 653 1.20 647 784

Prior to 1800 Total P=0.6 to 0.8 mg/g=600-800 mg/kg

Engstrom et al. 2009

g g g g

1960-1980 Total P=<1.8 mg/g=1800 mg/kg

P Adsorption CurveP Adsorption CurveP Adsorption CurveP Adsorption Curve8

l

4/kg

Sample # 100

4

tion,

mg/ EPC0=0.076 mg/L

00 0.04 0.08 0.12 0.16

So

rpt

y = 84.83x - 6.4306R² = 0.9798

-4

-8 Soluble P Concentration, mg/L

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FindingsFindingsFindingsFindings

P in Lake Pepin sediments from 1400P in Lake Pepin sediments from 1400--P in Lake Pepin sediments from 1400P in Lake Pepin sediments from 14001850 can be explained based on bank 1850 can be explained based on bank sediment enrichmentsediment enrichmentsediment enrichment.sediment enrichment.

Subsequent increases in lake sediment Subsequent increases in lake sediment appears to be linked to past practices of Pappears to be linked to past practices of Pappears to be linked to past practices of P appears to be linked to past practices of P input in rivers and P adsorption by river input in rivers and P adsorption by river sediments as they are tumblingsediments as they are tumblingsediments as they are tumbling sediments as they are tumbling downstream.downstream.

Conclusion IConclusion IConclusion IConclusion ISediment production has not changed

d ti ll Th dditi l di tdrastically. There are some additional sediments coming from agricultural fields.

Sediment transport has changed drastically.

More research is needed to quantify the effects h l difi ti i d i ichannel modifications, increased impervious

surfaces, and increased precipitation on sediment transportsediment transport.

Researchers and FundingResearchers and FundingResearchers and FundingResearchers and FundingDrew Kessler, University of Minnesota Drew Kessler, University of Minnesota yyAshley Ashley GrundtnerGrundtner, University of Minnesota, University of MinnesotaDr HollyDr Holly DolliverDolliver University of WisconsinUniversity of WisconsinDr. Holly Dr. Holly DolliverDolliver, University of Wisconsin, University of WisconsinDr. David Dr. David ThomaThoma, National Park Service, National Park Service

The project was supported with funds from The project was supported with funds from jjthe Minnesota Corn Growers Association the Minnesota Corn Growers Association and the Minnesota Soybean Research and and the Minnesota Soybean Research and yyPromotion Council.Promotion Council.

Thank youy