What is the Coastal Processes Technical WorkGroup doing?

This Group is studying the impacts of alternative water level regulation plans on:

• Shoreline erosion∑ • Flooding • Impacts to existing shore

protection structures, and • Impacts to barrier and

recreational beaches

What areas are we evaluating?2

Within the twoseparate geographical areas of the study:

• ∑ Lake Ontario and the St. Lawrence River upstream of the Moses-

Saunders Power dam (Lake and Upper River) and

• ∑ ∑The St. Lawrence River from Moses-Saunders Power Dam to Trois-Rivieres (Lower River).

Twenty-seven sites with a variety of shore types and development were studied in detail. This guided developement of evaluation methods for all of the shoreline.

How are we evaluating impacts?

Initially existing and new data were collected on:

• Waves, • Shoreline composition, • Bathymetric data, and • Land uses.

This information was integrated into erosion and flooding models to define how the shoreline responds to fluctuating water levels.

What are our findings to date?

• Shoreline erosion is highest during storm periods in the fall, winter, and spring. In the

summer, damaging storms are less severe and frequent.

∑ • Shoreline flooding damages are significant on both the Lake and the lower River.

∑ • Flood damages on the lower River are most severe in the Lac St. Pierre/Sorel area.

∑ • Sediment eroded from the bluff shorelines plays an important role in stabilizing sandy beaches and dune environments. Without erosion, the quality of beach and dune environments will degrade.

∑ • In the lower St. Lawrence River, shoreline erosion is primarily ship-wave driven. Water levels play a role in erosion, but regulation of Lake Ontario has a minor influence relative to large seasonal fluctuations in River flows and levels.

∑ • Lake level regulation scenarios that increase water levels on the Lake or River could necessitate modification to the crest elevations of shore protection structures to ensure the same level of protection.

∑ • The water levels resulting from the current operation of the Moses Saunders Power Dam have reduced shoreline erosion rates on Lake Ontario.

∑ • Erosion of Lake Ontario bluffs and shoreline is generally reduced for lake level regulation scenarios that result in low lake levels. However,

even during low lake levels erosion of the lake bottom occurs near the shoreline,

which allows for deeper water and bigger waves during the next high water period.

What is the Coastal Processes Technical WorkGroup doing?

4Photo - Baird & Asso

ciates

0 60 120 180 240 300 360 420 480 540 600

Time (s)

Wake due to passing ship(H = 45cm or 17.72 inches)

Drawdown wave dueto passing ship

(H = 60cm or 23.62 inches)

Elev

atio

n of

wat

er s

urfa

ce (

inch

es)

Elev

atio

n of

wat

er s

urfa

ce (

m)

Wind waves height(H = 10cm or 3.94 inches)

15.75

7.87

0.0

-15.75

-7.87

-23.62-0.6

-0.4

-0.2

0.0

0.2

0.4

Plot showing relative magnitudes of wind waves and ship waves

Data collected by Pacific International Engineering at the St. Lawrence River, October 2002

1

3

Coastal Processes

R1

R2

US8

US1

R3

US2

CND1 1

CND9

CND7

CND1

US3

US4

CND12

CND8

US7

CND4

CND10

US5

CND5

CND3

CND6

US6

CND2

0 25

N

S

EW

50 75 100Km

R3 Lake St. LawrenceR2 Morrisburg to Jones Creek MarshR1 Chippewa Point to Wolfe Island

US8 Tibbits Point to Stony CreekUS7 Eastern Lake OntarioUS6 Mexico Point to Oswego County LineUS5 Oswego County Line to East of Little Sodus BayUS4 Little Sodus Bay to Sodus BayUS3 Sodus Point to WebsterUS2 Irondequiot Bay to Point BreezeUS1 Lakeside Beach State Park to Niagara River

CND1 NiagaraCND2 Hamilton/Burlington BeachCND3 Hamilton HarbourCND4 Halton and PeelCND5 TorontoCND6 Scarborough BluffsCND7 East Point to Port HopeCND8 Port Hope to Presqu’ileCND9 Presqu’ile to Long Point CND10 Prince Edward Bay CND11 Bay of Quinte CND12 Kingston

14%11%3%

36% 36%

59%

5%

36%

3%8%

39%

1% 1%

48%

13%1%

26%

60%

3% 1%6%

71%

19%

31%

32%4%

33%

60%30%

10%

24%

16%30%

3%

27%

21%

1% 38%

21%

12%2%5%

11%7%

82%

21%

3%

15%31%

26%4%

63%24%

2%11%

20%

2%22%

43%1%

6%6%7%

79%

7% 7%

12%

33%55%

36%

4%

28%

1%3%

28%

71%

18%

11%

33%

4% 32%

31%

26%

64%

6%4%

1%

34%23%

14%

2%11%15%

12%

48%7%

33%

36%

4%0.2%

0.4%

57%

3%

11%4%

71%

14%

Shoreline Class

Sand or Cohesive Bluffs

Low Bank

Baymouth Barrier Complex

Sandy Beach / Dune Complex

Coarse Beaches/

Bedrock (Resistant)

Bedrock (Erosive)

Open Shoreline Wetlands

Artificial

Lake / LacOntario

N

Trois-Rivières

SorelLanoraie

Varennes

0 15 30

kilometers

Legend

Montréal

Deux-Montagnes

Cornwall

Sorel Island and Lake St. Pierre Section

Montreal-Lanoraie Section

Lake St.-Louis Section

Lake Deux-Montagne Section

Lake St. Francois Section

Irondequoit Bay to Point Breeze

Genesee River

PayneBeach

SandyHarborBeach

Holley

Hilton

Greece

Bergen

Albion

Kendall

Brighton

Rochester

Henrietta

Brockport

North Chili

Irondequoit

Gates Centre

East Rochester

86420Km

21%

3%

15%31%

26%4%

40% 58%

2%

28%

8%

8%

36%

20%

5%4%

2%

25%

56%

8%

Detailed Study Sites in R2Site 1: Payne Beach, Monroe CountySite 2: Sandy Harbor Beach Monroe CountySite 3: Edgemere Drive, Greece

LakeOntario

4

121080

1070

1060

1050

1040

1020

1030 1010

1000 0990

0980

0960

0950

0940

0970

US2

Shoreline Class

Nearshore Class

Level 1 and 2 ShorelineProtection Class

Land Use Class

N

S

EW

Sand or Cohesive Bluffs

Low Rank

Baymouth Barrier Complex

Sandy Beach / Dune complex

Open Shoreline Wetlands

Artifical

Cobble / Boulder Lag Over Cohesive

Bedrock (Erosive)

Creek / Harbor Sediments

0 - no structures

1 - 25% per reach

26 - 50% per reach

51 - 75% per reach

>~75% per reach

Residential / Cottage

Industrial / Commercial

Transportation

Agriculture

Parks and Rec. Areas

Natural

Irondequoit Bay

Shore Unit US 2:reach: 943 to 1083lenght: 141 km (87.61 miles)