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Coastal & Marine Geology Program > Coastal Classification Mapping Project > Open File Report 2006-1096

Coastal Classification Atlas

Central Texas Coastal Classification Maps - Aransas Pass to Mansfield Channel

USGS Open File Report 2006-1096

Robert A. Morton, Russell L. Peterson

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 149.6-km-long segment of coast between Aransas Pass and Mansfield Channel are presented for each classification unit in Table 2. Ninety three percent of this coastal segment is undeveloped, and where it is developed, the development is mostly low to moderate density (Table 2). Single-family homes are slightly less common than multi-family units such as high-rise condominiums and hotels, and 78% of the shore is classified as parks (Table 2). This includes state and county parks as well as Padre Island National Seashore. About 75% of the shore has high continuous dunes and discontinuous dunes cover an additional 23% of the shore. Because the dunes are mainly continuous, complete overwash occurs only along 1% of the shore (Table 2). The closed inlet and new inlet categories (Table 2) refer, respectively, to the Fish Pass at Mustang Island State Park and the recently reopened Packery Channel that separates Mustang and North Padre Islands. Seventy six percent of the shore is characterized by natural beaches more than 30 m wide (Table 2); wide maintained beaches account for another 22% of the shore. Because the beaches are wide and mostly undeveloped, there is little need for shoreline stabilization structures. Only about 1% of the shore is influenced by hard structures (Table 2); the most extensive structure is the seawall built in the backbeach on North Padre Island.

Table 2. Lengths of shore and percentages for the classification units mapped between Aransas Pass and Mansfield Channel. Total length of this coastal segment is about 149.6 km.
Category Classification Length (km) Percent Pie Chart
Overwash Overwash 1.9 1 Overwash pie chart - overwash 1%, closed inlet <1%, new inlet <1%, no overwash 99%
Closed inlet 0.1 <1
New inlet 0.1 <1
No overwash 147.5 99
Dunes Absent 1.3 1 Dune Presence pie chart - absent 1%,  continuous 75%, discontinuous 23%, overwash terrace 1%
Continuous 112.0 75
Discontinuous 34.8 23
Overwash terrace 1.5 1
Beach width > 30 m natural 113.6 76 Beach width pie chart - greater than 30 meters natural 76%; greater than 30 meters maintained 22%, less than 30 meters natual 1%, less than 30 meters maintained 1%
> 30 m maintained 33.6 22
< 30 m natural 1.2 1
< 30 m maintained 1.3 1
Structures No structure 148.0 99 Structures pie chart - no structure 99%, wall 1%, groins less than 1%
Wall 1.4 1
Riprap 0.0 0
Groins 0.2 <1%
Multiple structures 0.0 0
Development Density Undeveloped 138.5 93 Density of development pie chart - undevelopled 93%, low density 5%, moderate density 2%, less than 1%
Low density 8.2 5
Moderate density 2.5 2
High density 0.4 <1
Dwelling Type No dwelling 25.5 17 Dwelling type pie chart - no dwelling 17%, single family 2%, mixed  less than 1%, multi-unit 3%, park 78%, industrial/commercial less than 1%
Single family 2.3 2
Mixed 0.7 <1
Multi-unit 3.7 3
Park 117.1 78
Indust./Commercial 0.4 <1

Coastal & Marine Geology Program > Coastal Classification Mapping Project > Open File Report 2006-1096

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