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Coastal & Marine Geology Program > Coastal Classification Mapping Project > Open File Report 03-322

Coastal Classification Atlas

Southwestern Florida Coastal Classification Maps - Venice Inlet to Cape Romano

USGS Open File Report 03-322

Robert A. Morton, Russell L. Peterson

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Classification Summary

The coastal classification maps provide a basis for establishing the lengths of shore that have a particular morphological characteristic or cultural attribute. Such information is relevant for local and state governments for planning that involves the amount of shore that is developed versus undeveloped, or the amount of parkland held in the public trust. Also there is interest regarding the amount of shore that is affected by engineering structures, referred to as armoring or hardening of the shore. Environmental protection and resource management issues such as these require quantitative data that can be derived from the classification maps.

The shore lengths and equivalent percents of the 177 km segment of coast between Venice inlet and Cape Romano are presented for each classification unit in Table 2. The percents are shown graphically in the last column of Table 2. Nearly two-thirds of this coastal segment is developed, and the development is mostly moderate to high density (Table 2). Single-family homes are more common than multi-family units such as high-rise condominiums and hotels, and only nine percent of the shore is classified as parks (Table 2). Dunes are not well developed along this coastal sector and continuous dunes are present on only 8% of the shore. Discontinuous dunes represent another 7% of the shore. A washover terrace occupies most (70%) of the area landward of the backbeach. Beaches are more than 30 m wide or there is a protective emergent bar for approximately 60% of the shore (Table 2), but beach width can vary greatly because beach nourishment is common for this region. Despite low elevations and narrow barrier widths (Table 2), areas of complete storm overwash represent only one percent of the total shore. Only about 16% of the shore is influenced by hard structures, most of the structures are seawalls or bulkheads built in the backbeach area (Table 2).

Table 2. Lengths of shore and percentages for the classification units mapped between Venice Inlet and Cape Romano. Total length of this coastal segment is about 177 km.
Category Classification Length (km) Percent Pie Chart
Washover Overwash 2.6 1 Washover pie chart.
Closed inlet 0.4 0
New Inlet 0.1 0
No overwash 174 99
Dunes Absent 27.4 16 Dune Presence pie chart.
Continuous 14.5 8
Discontinuous 11.9 7
Washover terrace 112.9 63
Washover terrace/ridge 10.3 6
Beach width > 30 m natural 81.8 47 Beach width pie chart.
> 30 m maintained 15.6 9
< 30 m natural 71.5 40
< 30 m maintained 0.3 0
exposed bar 7.8 4
Structures No structure 149.5 85 Structures pie chart.
Wall 11.2 7
Riprap 4.1 2
Groins 2.8 2
Multiple structures 7.8 4
Outfall 0.8 0
Breakwater 0.6 0
Geotube 0.1 0
Development Density Undeveloped 62.2 35 Density of development pie chart.
Low density 24.4 14
Moderate density 34.7 20
High density 55.8 31
Dwelling Type No dwelling 58.4 33 Dwelling type pie chart.
Single family 54.4 31
Mixed 9.5 5
Multi-unit 38.7 22
Park 16.2 9

Coastal & Marine Geology Program > Coastal Classification Mapping Project > Open File Report 03-322

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