coastal processes - international joint commission - twg coastal... · coastal processes r1 r2 us8...
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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)