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Estimate Future Structural Shore Protection Trends
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The objective of this task is to estimate future structural shore protection trends along each reach of shoreline in each of the five prototype counties for each of the five alternate water level scenarios under consideration. The current shoreline classification database includes an inventory of shore protection type, level of performance and spatial coverage based on a review of 1997 aerial photography.
In 1999, work was conducted by Orca Technologies International Inc. to inventory and map historic trends in shore protection construction in the 5 prototype counties, with a goal of using this information to predict future trends over the next 50 years. Mapping was conducted using 1:6000 scale 1989 and 1999 aerial photography for Ottawa and Allegan Counties, in Michigan and 1978 and 1992 air photography for Ozaukee, Sheboygan and Manitowoc Counties in Wisconsin. To allow for ease of mapping, the 1-kilometer reach segments in each county were further divided into 1/10th of a kilometer segments. All shore protection types present and visible in the photographs were then measured and recorded on this 1/10th of a kilometer basis. The reclassification was done using the existing shoreline protection classification, which also included a quality assessment. Changes in the lengths and percentages of each shore protection type present were then assessed on three scales including 1/10th of a kilometer, a kilometer reach basis, and by county. County level summary data for each of the prototype counties are available below.
Ottawa County Summary Statistics
Shore Protection Type | 89 LENGTH (M) | %COUNTY | 99 LENGTH (M) | % COUNTY | CHG (M) | CHG (%) | | | | | | | | | 1A1 - Revetments >45 Year Lifespan | 300 | 0.73 | 800 | 1.95 | 500 | 1.22 | 1A2 - Revetments 5-45 Year Lifespan | 375 | 0.91 | 515 | 1.26 | 140 | 0.34 | | | | | | | | | 1B2 - Seawalls/Bulkheads 5-45 Year Lifespan | 1527 | 3.72 | 2270 | 5.54 | 743 | 1.81 | 1B3 - Seawalls/Bulkheads 0-5 Year Lifespan | 1415 | 3.45 | 915 | 2.23 | -500 | -1.22 | | | | | | | | | 2A2 - Groins 5-45 Year Lifespan | 6585 | 16.06 | 6335 | 15.45 | -250 | -0.61 | 2A3 - Groins 0-5 Year Lifespan | 1375 | 3.35 | 425 | 1.04 | -950 | -2.32 | 2A4 - Groins 0 Year Lifespan (Disrepair) | 140 | 0.34 | 140 | 0.34 | 0 | 0.00 | | | | | | | | | 2B1 - Jetties | 744 | 1.81 | 744 | 1.81 | 0 | 0.00 | | | | | | | | | 3A2 - Beach Nourishment | 1100 | 2.68 | 1600 | 3.90 | 500 | 1.22 | | | | | | | | | 5B4 - AdHoc, Other Materials, 0 Year Lifespan (Disrepair) | 10 | 0.02 | 0 | 0.00 | -10 | -0.02 | | | | | | | | | 7 - Unprotected | 30152 | 73.54 | 29561 | 72.10 | -591 | -1.44 | | | | | | | | | Note: Percentages Expressed as a Percentage of 41km length for entire county | | | | | | | | | | | | | | | Quick Analysis: | | | | | | | 0.5 km of new shore protection added in 10 years (I.e., loss of 591m of "unprotected) | | | | | | Addition of 640 m of new revetments in 10 yrs?1.2% increase | | | | | | | Loss of over 1 km of groins | | | | | | | Increase in Beach Nourishment - Function of Snapshots in Time | | | | | |
Allegan County Summary Statistics
Shore Protection Type | 89 Length (M) | %COUNTY | 99 LENGTH (M) | % COUNTY | CHG (M) | CHG (%) | | | | | | | | | 1A1 - Revetments >45 Year Lifespan | 750 | 1.88 | 750 | 1.88 | 0 | 0.00 | 1A2 - Revetments 5-45 Year Lifespan | 485 | 1.21 | 1065 | 2.66 | 580 | 1.45 | 1A3 - Revetments 0-5 Year Lifespan | 765 | 1.91 | 65 | 0.16 | -700 | -1.75 | 1A4 - Revetments 0 Year Lifespan (Disrepair) | 0 | 0.00 | 75 | 0.19 | 75 | 0.19 | | | | | | | | | 1B2 - Seawalls/Bulkheads 5-45 Year Lifespan | 1570 | 3.93 | 2445 | 6.11 | 875 | 2.19 | 1B3 - Seawalls/Bulkheads 0-5 Year Lifespan | 350 | 0.88 | 0 | 0.00 | -350 | -0.88 | 1B4 - Seawall/Bulkhead 0 Year Lifespan (Disrepair) | 0 | 0.00 | 75 | 0.19 | 75 | 0.19 | | | | | | | | | 2A2 - Groins 5-45 Year Lifespan | 1375 | 3.44 | 1855 | 4.64 | 480 | 1.20 | 2A4 - Groins 0 Year Lifespan (Disrepair) | 0 | 0.00 | 35 | 0.09 | 35 | 0.09 | | | | | | | | | 2B1 - Jetties | 100 | 0.25 | 100 | 0.25 | 0 | 0.00 | | | | | | | | | 3C1 - Slope/Bluff Stabilization >45 Year Lifespan | 250 | 0.63 | 250 | 0.63 | 0 | 0.00 | 3C2 - Slope/Bluff Stabilization 5-45 Year Lifespan | 0 | 0.00 | 400 | 1.00 | 400 | 1.00 | | | | | | | | | 5A2 - Ad Hoc, Concrete Rubble 5-45 Year Lifespan | 210 | 0.53 | 210 | 0.53 | 0 | 0.00 | 5A3 - Ad Hoc, Concrete Rubble 0-5 Year Lifespan | 200 | 0.50 | 100 | 0.25 | -100 | -0.25 | 5A4 - Ad Hoc, Concrete Rubble 0 Year Lifespan (Disrepair) | 315 | 0.79 | 885 | 2.21 | 570 | 1.43 | | | | | | | | | 5B2 - AdHoc, Other Materials, 5-45 Year Lifespan | 350 | 0.88 | 0 | 0.00 | -350 | -0.88 | 5B3 - AdHoc, Other Materials, 0-5 Year Lifespan | 300 | 0.75 | 600 | 1.50 | 300 | 0.75 | 5B4 - AdHoc, Other Materials, 0 Year Lifespan (Disrepair) | 0 | 0.00 | 65 | 0.16 | 65 | 0.16 | | | | | | | | | 7 - Unprotected | 33170 | 82.93 | 31550 | 78.88 | -1620 | -4.05 | | | | | | | | | Note: Percentages Expressed as a Percentage of 40km length for entire county | | | | | | | | | | | | | | | Quick Analysis: | | | | | | | 1.6km of New Shore Protection in 10 Years | | | | | | | Higher use of Ad Hoc Materials than Ottawa County | | | | | | | .8 km of seawalls added, plus reduction in lower quality walls?replacement? | | | | | | | Almost 0.5 km addition of groynes?Holmberg Tubes? | | | | | |
Ozaukee County Summary Statistics Shore Protection Type | 78 LENGTH (M) | %COUNTY | 92 LENGTH (M) | % COUNTY | CHG (M) | CHG (%) | | | | | | | | | 1A1 - Revetments >45 Year Lifespan | 838 | 1.90 | 1038 | 2.36 | 200 | 0.45 | 1A2 - Revetments 5-45 Year Lifespan | 1120 | 2.55 | 2450 | 5.57 | 1330 | 3.02 | 1A3 - Revetments 0-5 Year Lifespan | 895 | 2.03 | 805 | 1.83 | -90 | -0.20 | 1A4 - Revetments 0 Year Lifespan (Disrepair) | 0 | 0.00 | 255 | 0.58 | 255 | 0.58 | | | | | | | | | 1B1 - Seawalls/Bulkheads >45 Year Lifespan | 1682 | 3.82 | 2107 | 4.79 | 425 | 0.97 | 1B2 - Seawalls/Bulkheads 5-45 Year Lifespan | 840 | 1.91 | 1050 | 2.39 | 210 | 0.48 | 1B3 - Seawalls/Bulkheads 0-5 Year Lifespan | 230 | 0.52 | 260 | 0.59 | 30 | 0.07 | | | | | | | | | 2A2 - Groins 5-45 Year Lifespan | 150 | 0.34 | 0 | 0.00 | -150 | -0.34 | | | | | | | | | 2B1 - Jetties | 200 | 0.45 | 200 | 0.45 | 0 | 0.00 | | | | | | | | | 2C1 - Offshore Breakwaters, > 45 Year Lifespan | 0 | 0.00 | 200 | 0.45 | 200 | 0.45 | | | | | | | | | 5A2 - Ad Hoc, Concrete, 5-45 Year Lifespan | 457 | 1.04 | 437 | 0.99 | -20 | -0.05 | 5A3 - Ad Hoc, Concrete, 0-5 Year Lifespan | 580 | 1.32 | 760 | 1.73 | 180 | 0.41 | 5A4 - Ad Hoc, Concrete, 0 Year Lifespan (Disrepair) | 325 | 0.74 | 25 | 0.06 | -300 | -0.68 | | | | | | | | | 5B2 - Ad Hoc, Other Materials, 5-45 Year Lifespan | 30 | 0.07 | 30 | 0.07 | 0 | 0.00 | 5B4 - AdHoc, Other Materials, 0 Year Lifespan (Disrepair) | 0 | 0.00 | 25 | 0.06 | 25 | 0.06 | | | | | | | | | 7 - Unprotected | 37153 | 84.44 | 35168 | 79.93 | -1985 | -4.51 | | | | | | | | | Note: Percentages Expressed as a Percentage of 44km length for entire county | | | | | | | | | | | | | | | Quick Analysis: | | | | | | | Almost 2 km of New Shore Protection Added | | | | | | | 1.3km of 1a2 Revetment Added | | | | | | | Next biggest addition is 425m of seawall |
Sheboygan County Summary Statistics
Shore Protection Type | 78 LENGTH (M) | %COUNTY | 92 LENGTH (M) | % COUNTY | CHG (M) | CHG (%) | | | | | | | | | 1A1 - Revetments >45 Year Lifespan | 3290 | 7.15 | 5440 | 11.83 | 2150 | 4.67 | 1A2 - Revetments 5-45 Year Lifespan | 4235 | 9.21 | 5895 | 12.82 | 1660 | 3.61 | 1A3 - Revetments 0-5 Year Lifespan | 3140 | 6.83 | 2070 | 4.50 | -1070 | -2.33 | 1A4 - Revetments 0 Year Lifespan (Disrepair) | 255 | 0.55 | 0 | 0.00 | -255 | -0.55 | | | | | | | | | 1B1 - Seawalls/Bulkheads >45 Year Lifespan | 3000 | 6.52 | 3320 | 7.22 | 320 | 0.70 | 1B2 - Seawalls/Bulkheads 5-45 Year Lifespan | 1125 | 2.45 | 1050 | 2.28 | -75 | -0.16 | 1B3 - Seawalls/Bulkheads 0-5 Year Lifespan | 725 | 1.58 | 310 | 0.67 | -415 | -0.90 | 1B4 - Seawalls/Bulkheads 0 Year Lifespan (Disrepair) | 0 | 0.00 | 75 | 0.16 | 75 | 0.16 | | | | | | | | | 2A1 - Groins >45 Year Lifespan | 1600 | 3.48 | 0 | 0.00 | -1600 | -3.48 | 2A2 - Groins 5-45 Year Lifespan | 275 | 0.60 | 400 | 0.87 | 125 | 0.27 | 2A3 - Groins 0-5 Year Lifespan | 0 | 0.00 | 1475 | 3.21 | 1475 | 3.21 | | | | | | | | | 2B1 - Jetties >45 Year Lifespan | 315 | 0.68 | 300 | 0.65 | -15 | -0.03 | | | | | | | | | 2C1 - Offshore Breakwaters, > 45 Year Lifespan | 0 | 0.00 | 250 | 0.54 | 250 | 0.54 | | | | | | | | | 5A2 - Ad Hoc, Concrete, 5-45 Year Lifespan | 40 | 0.09 | 680 | 1.48 | 640 | 1.39 | 5A3 - Ad Hoc, Concrete, 0-5 Year Lifespan | 595 | 1.29 | 245 | 0.53 | -350 | -0.76 | 5A4 - Ad Hoc, Concrete, 0 Year Lifespan (Disrepair) | 1250 | 2.72 | 1295 | 2.82 | 45 | 0.10 | | | | | | | | | 5B3 - Ad Hoc, Other Materials, 0-5 Year Lifespan | 35 | 0.08 | 0 | 0.00 | -35 | -0.08 | | | | | | | | | 7 - Unprotected | 27720 | 60.26 | 25595 | 55.64 | -2125 | -4.62 | | | | | | | | | Note: Percentages Expressed as a Percentage of 46km length for entire county | | | | | | | | | | | | | | Quick Analysis: | | | | | | | Changes in Groins due to deterioration of one large group | | | | | | | Largest change addition of mid to high quality revetments | | | | | | | Revetments and Seawalls Predominate | | | | | | | Largest range in quality for structures found | | | | | | | 27.7km unprotected in 1978?25.5 unprotected in 1992?loss of 152m per year | | | | | |
Manitowoc County Summary Statistics
Shore Protection Type | 78 LENGTH (M) | %COUNTY | 92 LENGTH (M) | % COUNTY | CHG (M) | CHG (%) | | | | | | | | | 1A1 - Revetments >45 Year Lifespan | 7880 | 13.82 | 9335 | 16.38 | 1455 | 2.55 | 1A2 - Revetments 5-45 Year Lifespan | 1485 | 2.61 | 2965 | 5.20 | 1480 | 2.60 | 1A3 - Revetments 0-5 Year Lifespan | 285 | 0.50 | 570 | 1.00 | 285 | 0.50 | 1A4 - Revetments 0 Year Lifespan (Disrepair) | 45 | 0.08 | 0 | 0.00 | -45 | -0.08 | | | | | | | | | 1B1 - Seawalls/Bulkheads >45 Year Lifespan | 30 | 0.05 | 30 | 0.05 | 0 | 0.00 | 1B2 - Seawalls/Bulkheads 5-45 Year Lifespan | 45 | 0.08 | 110 | 0.19 | 65 | 0.11 | 1B3 - Seawalls/Bulkheads 0-5 Year Lifespan | 25 | 0.04 | 0 | 0.00 | -25 | -0.04 | | | | | | | | | 2A2 - Groins 5-45 Year Lifespan | 335 | 0.59 | 335 | 0.59 | 0 | 0.00 | | | | | | | | | 2B1 - Jetties >45 Year Lifespan | 1070 | 1.88 | 1070 | 1.88 | 0 | 0.00 | | | | | | | | | 5A3 - Ad Hoc, Concrete, 0-5 Year Lifespan | 125 | 0.22 | 100 | 0.18 | -25 | -0.04 | 5A4 - Ad Hoc, Concrete, 0 Year Lifespan (Disrepair) | 200 | 0.35 | 200 | 0.35 | 0 | 0.00 | | | | | | | | | 5B4 - AdHoc, Other Materials, 0 Year Lifespan (Disrepair) | 225 | 0.39 | 100 | 0.18 | -125 | -0.22 | | | | | | | | | 7 - Unprotected | 45485 | 79.80 | 42420 | 74.42 | -3065 | -5.38 | | | | | | | | | Note: Percentages Expressed as a Percentage of 57km length for entire county | | | | | | | | | | | | | | | Quick Analysis: | | | | | | | ~80% of county unprotected in 1978, 74%in 1992?armoring rate of 218m per year | | | | | | | Where SP exists it is primarily revetment | | | | | | | >5% increase in construction/improvements to revetments | | | | | | | | | | | | | |
The columns in each table present the length and percentage (by county length) of each shore protection type in the two years of analysis, as well as associated changes in these lengths and percentages over the time period between the two photos. A "Quick Analysis" of the county level data has also been provided at the bottom of each table. Detailed analysis of this data is now taking place to assess and correlate these changes with such things as water levels, shore type, and erosion rates. Estimates are also being made as to the dollar costs of the shore protection (on a linear meter basis), as well as increases or decreases in costs associated with the changes. This information will be summarized in the final version of this Progress Report slated for December 1999. It is intended that this data be extrapolated over the future planning horizons for each of the water level scenarios, and combined with information gleaned from the focus group sessions (see below) in order to produce likely future costs of shoreline protection in the prototype counties. Click to return to the GIS Analyses Home Page.
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