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Planning & Environmental Branch
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National Erosion Control Development and Demonstration Program (Section
227): Jefferson County, Texas
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| Background: |
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The project location fronts the McFaddin National
Wildlife Refuge in the vicinity of High Island, Texas, 49 km
west of the Texas and Louisiana border. Beaches at the
demonstration area consist of a thin sand veneer over mud. Wave
heights average between 0.76 m (2.5 ft) and 1.4 m (4.6 ft), with
much higher waves occurring during storms. Mean tide range is
0.39 m (1.28 ft). The average long-term shoreline erosion rate
is approximately 1.5 m, annually. Since 1980, most of the
roadway spanning the coast between High Island and Sabine Pass,
TX, has been closed due to coastal erosion. |
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| Problem: |
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Storms erode the thin layer of sand, exposing the
mud to further erosion. During storms, beach sediment that is
not pulled offshore may be washed over the low-laying dune and
deposited in a wetland area landward of the beach. Overwashed
sediment is not recovered from the wetland and returned to the
beach profile. The beach profile has limited post-storm recovery
due to a deficit of sediment in the littoral system. |
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| Technology: |
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The primary objectives the project will be to
minimize erosion of the exposed cohesive sediment and to
minimize sand overwash. These objectives will be accomplished by
constructing experimental low-volume beach nourishment templates
contained by geotextile tube groin cells, and dune construction.
The 762-m- (2,500-ft-) long dune is designed to withstand a
5-year return period storm. Fronting half of the engineered dune
corridor is beach nourishment divided into four experimental
cells of varying fill volume and grain size. The objective of
the nourishment is to investigate the longevity of minimal fill
volumes (6 to 12 yd3/ft or 15 to 30 m3/m) combined with native
beach sand (0.17 mm < d50 < 0.21 mm) or sand larger than
what is naturally present on the active beach profile (0.31 mm
< d50 < 0.40 mm). A geotextile tube groin separates each
experimental cell. The function of the tube is to only contain
the experimental areas. |
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| Status: |
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The Final Environmental Assessment has been
approved and the Findings-of-No-Significant-Impact (FONSI) was
signed in the fall of 2003. The Memorandum of Agreement with the
Texas General Land Office has been signed and the Operations,
Maintenance, Repair, Replacement and Rehabilitation Manual
completed. Construction was completed in July of 2004. A
36-month project-monitoring program was established following
completion of construction and will include cross-shore beach
profiles, aerial photography, sediment samples, water-level
measurements, structure inspection, and data management and
analysis. An improved overwash algorithm, applicable to low
barriers such as at Jefferson County, has been developed and
will be implemented in SBEACH for project evaluation. |
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| Contact: |
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Dr.
Jeff Waters
409-766-3127 |
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| Documents: |
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This is an official US
Government webpage. This webpage is intended to provide
information of general interest to the public. The
information contained herein is accurate as of the date of
publication.
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Updated:
September 20, 2004
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