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Coastal & Marine Geology Program > Coastal Classification Mapping Project > Open File Report 2005-1261

Coastal Classification Atlas

Western Louisiana Coastal Classification Maps - Lower Mud Lake Entrance Channel to Sabine Pass

USGS Open File Report 2005-1261

Robert A. Morton, Russell L. Peterson, Tara L. Miller

Report Home Maps Overview Mapping Methods Coastal Classifications Geologic Setting Coastal Processes Coastal Vulnerability Classification Summary References

Classification Summary

The coastal classification maps provide a basis for establishing the lengths of shore that have a particular morphological characteristic or urban 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 82-km-long segment of coast between Lower Mud Lake Entrance Channel and Sabine Pass are presented for each classification unit in Table 2. Eighty-six percent of this coastal segment is undeveloped, and where it is developed, the development is mostly low density (Table 2). Single-family homes (12%) and industrial infrastructure (1%) are the only types of development, and 3% of the shore is classified as park (Table 2). An overwash terrace is present along 97% of the shore (Table 2), but there are no areas of complete overwash because there are no permanent water bodies parallel to the shore, like those adjacent to barrier islands. A low artificial dune ridge was constructed at Holly Beach that in its natural state would have been classified as overwash terrace. Only 21% of the shore is characterized by natural beaches more than 30 meters wide (Table 2). Because the beaches are narrow, rapidly eroding, and contain abundant shell, there is little need to maintain the beaches (4%, Table 2). Only 14% of the shore is influenced by hard structures (Table 2); most of the structures are riprap revetments built in the backbeach area or segmented breakwaters constructed offshore.

Table 2. Lengths of shore and percentages for the classification units mapped between Lower Mud Lake Entrance Channel and Sabine Pass. Total length of this coastal segment is about 82 km.
Category Classification Length (km) Percent Pie Chart
Overwash Overwash 0.0 0
Closed inlet 0.0 0
New Inlet 0.0 0
No overwash 82 100
Dunes Absent 1.8 2 Dune Presence pie chart - absent 2%, overwash terrace 97%, artificial dune 1%
Artificial dune ridge 0.9 1
Discontinuous 0.0 0
Overwash terrace 79.6 97
Beach width > 30 m natural 17.1 21 Beach width pie chart - greater than 30 meters maintained 3%; greater than 30 meters natural 21%, less than 30 maintained 1%, less than 30 meters natural 75%
> 30 m maintained 2.3 3
< 30 m natural 62.2 75
< 30 m maintained 0.7 1
Structures No structure 70.5 86 Structures pie chart - multiple structures 9%, no structure 86%, breakwater 5%
Breakwaters 4.0 5
Multiple structures 7.8 9
Development Density Undeveloped 71.0 86 Density of development pie chart - high density 2%, moderate density 2%, low density 10%, undeveloped 86%
Low density 8.1 10
Moderate density 1.5 2
High density 1.6 2
Dwelling Type No dwelling 68.8 84 Dwelling type pie chart - single family 12%, no dwelling 84%, park 3%, industrial/commercial 1%
Single family 10.2 12
Industrial/commercial 1.0 1
Park 2.2 3

Coastal & Marine Geology Program > Coastal Classification Mapping Project > Open File Report 2005-1261

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