Geo tubes will save homes and dunes and make the beaches better
- Thread starter EZ4144
- Start date
-
Trouble logging in? Send us a message with your username and/or email address for help.
The State of Texas has studied geotubes and has a lot of good data online: http://www.beg.utexas.edu/coastal/geotube.htm
Final report .pdf - has some good photos
...Because the geotextile tubes cannot be recovered through natural processes, covering them requires a significant effort. Furthermore, maintaining even a sparse vegetation cover on at least half of the project lengths has not been possible...
...Once the beach erodes to the base of the tubes, they become undermined and begin to slump seaward. Direct wave attack on the tubes quickly removes the sand cover, damages the ultraviolet radiation shroud, and causes punctures...
Conclusions
1. The storm-surge protection function of the geotextile tubes had not been fully tested as of March 2003.
2. The geotextile tubes will fail when exposed to direct wave attack making them useful only for short-term erosion control. This is evident in the failure of the Treasure Island middle project, and in the holes in the tube fabric and collapsed sections along the Gilchrist West project. To prevent failure it is critical to keep the tubes covered with sand, to maintain a beach in front of them, and to repair holes in the fabric as soon as possible. It is also important to note that, during storms, erosion and vegetation line retreat may occur landward of the geotextile tubes as was observed at the northern Treasure Island project.
3. Beaches in front of the geotextile tubes need to be at least 50-ft wide to keep the tubes from being exposed and damaged during a mild storm like TS Allison. A thick and vegetated sand cover on the tubes can partly compensate for a narrower beach.
4. During Tropical Storms Allison and Fay, the geotextile tubes prevented the vegetation line from retreating landward of houses. However, those houses to which the vegetation line would have retreated were probably seaward of the natural line of vegetation at the time the tubes were installed.
5. Because it is under the influence of San Luis Pass, the Treasure Island shoreline is historically dynamic undergoing periods of dramatic retreat and advance. However, net long-term shoreline movement is landward. The shoreline is currently in a retreat phase, and the geotextile tubes cannot stop the movement. Along the northern reach of the Treasure Island North project, erosion has proceeded behind the tubes.
6. Other than the special cases of the Treasure Island projects, the Gilchrist projects have proven to be the most difficult to keep covered with sand. The Gilchrist West project has the highest percentage per project of exposed geotextile tubes and contributes by far the greatest length of exposed and damaged tubes along the upper coast. The primary reason for this is the relatively seaward placement of the tubes causing narrower and lower beaches in front of them and thus less protection than at the other major projects.
7. In June 2001, after Tropical Storm Allison, 44% of the lengths of geotextile tubes were exposed along their seaward faces. Maintenance activity and fair weather conditions allowed the recovering of all but 15% of the project lengths by November 2001. Most of the exposed tubes are along the Gilchrist West project.
8. In September 2002, after Tropical Storm Fay, 79% of the lengths of geotextile tubes were exposed and 69% were still exposed by March 2003.
9. Keeping at least a 25% vegetation cover along the Gilchrist East, Gilchrist West, and Dellanera projects has not been possible.
10. Keeping the geotextile tubes repaired, sand covered, and vegetated requires a significant effort.
11. Beaches in front of the geotextile tubes are narrower than adjacent beaches. This is primarily because the tubes were installed farther seaward than the natural landward boundaries represented by the line of vegetation, foredunes, or bluffs.
12. Some geotextile tube segments were routed seaward of individual houses or groups of houses and departed from a shore-parallel orientation. These areas create particularly narrow beach segments that are not passable during times of moderately elevated water levels of 1 to 2 ft (0.30 to 0.61 m) above mean higher high water.
13. After rainfall, outflows from street drainage pipes along the Pirates Beach project erode channels perpendicular to the beach that at times hinder passage along the beach.
14. Geotextile tubes alter the natural geomorphology of the beach/dune system and have hindered the formation of coppice mounds and natural dunes.
15. The geotextile tubes have not enhanced erosion rates on adjacent beaches with the possible exception of the Treasure Island north project. If the beaches in front of the tubes are not nourished with sand from outside the littoral system, then there may be a small enhancement of erosion of adjacent beaches until the tubes are destroyed by wave action.
Final report .pdf - has some good photos
...The geotextile tubes have been effective for temporary erosion control, but they may fail when exposed to direct wave attack. During the study period, two of the Treasure Island (on Follets Island) geotextile tubes were destroyed and holes, slumping, and collapsed sections were observed along other projects. To prevent failure it is critical to (1) keep the geotextile tubes covered with sand, (2) maintain a beach in front of them through beach nourishment, and (3) repair holes in the fabric as soon as possible...
...Because the geotextile tubes cannot be recovered through natural processes, covering them requires a significant effort. Furthermore, maintaining even a sparse vegetation cover on at least half of the project lengths has not been possible...
...Once the beach erodes to the base of the tubes, they become undermined and begin to slump seaward. Direct wave attack on the tubes quickly removes the sand cover, damages the ultraviolet radiation shroud, and causes punctures...
Conclusions
1. The storm-surge protection function of the geotextile tubes had not been fully tested as of March 2003.
2. The geotextile tubes will fail when exposed to direct wave attack making them useful only for short-term erosion control. This is evident in the failure of the Treasure Island middle project, and in the holes in the tube fabric and collapsed sections along the Gilchrist West project. To prevent failure it is critical to keep the tubes covered with sand, to maintain a beach in front of them, and to repair holes in the fabric as soon as possible. It is also important to note that, during storms, erosion and vegetation line retreat may occur landward of the geotextile tubes as was observed at the northern Treasure Island project.
3. Beaches in front of the geotextile tubes need to be at least 50-ft wide to keep the tubes from being exposed and damaged during a mild storm like TS Allison. A thick and vegetated sand cover on the tubes can partly compensate for a narrower beach.
4. During Tropical Storms Allison and Fay, the geotextile tubes prevented the vegetation line from retreating landward of houses. However, those houses to which the vegetation line would have retreated were probably seaward of the natural line of vegetation at the time the tubes were installed.
5. Because it is under the influence of San Luis Pass, the Treasure Island shoreline is historically dynamic undergoing periods of dramatic retreat and advance. However, net long-term shoreline movement is landward. The shoreline is currently in a retreat phase, and the geotextile tubes cannot stop the movement. Along the northern reach of the Treasure Island North project, erosion has proceeded behind the tubes.
6. Other than the special cases of the Treasure Island projects, the Gilchrist projects have proven to be the most difficult to keep covered with sand. The Gilchrist West project has the highest percentage per project of exposed geotextile tubes and contributes by far the greatest length of exposed and damaged tubes along the upper coast. The primary reason for this is the relatively seaward placement of the tubes causing narrower and lower beaches in front of them and thus less protection than at the other major projects.
7. In June 2001, after Tropical Storm Allison, 44% of the lengths of geotextile tubes were exposed along their seaward faces. Maintenance activity and fair weather conditions allowed the recovering of all but 15% of the project lengths by November 2001. Most of the exposed tubes are along the Gilchrist West project.
8. In September 2002, after Tropical Storm Fay, 79% of the lengths of geotextile tubes were exposed and 69% were still exposed by March 2003.
9. Keeping at least a 25% vegetation cover along the Gilchrist East, Gilchrist West, and Dellanera projects has not been possible.
10. Keeping the geotextile tubes repaired, sand covered, and vegetated requires a significant effort.
11. Beaches in front of the geotextile tubes are narrower than adjacent beaches. This is primarily because the tubes were installed farther seaward than the natural landward boundaries represented by the line of vegetation, foredunes, or bluffs.
12. Some geotextile tube segments were routed seaward of individual houses or groups of houses and departed from a shore-parallel orientation. These areas create particularly narrow beach segments that are not passable during times of moderately elevated water levels of 1 to 2 ft (0.30 to 0.61 m) above mean higher high water.
13. After rainfall, outflows from street drainage pipes along the Pirates Beach project erode channels perpendicular to the beach that at times hinder passage along the beach.
14. Geotextile tubes alter the natural geomorphology of the beach/dune system and have hindered the formation of coppice mounds and natural dunes.
15. The geotextile tubes have not enhanced erosion rates on adjacent beaches with the possible exception of the Treasure Island north project. If the beaches in front of the tubes are not nourished with sand from outside the littoral system, then there may be a small enhancement of erosion of adjacent beaches until the tubes are destroyed by wave action.
lurker1 said:
I certainly do not want to cause or be blamed for my marker's ink destroying the tubes, thereby causing the failure of the geo tube's walls and the polution of the beach. Not my game.
EZ4144 said:Hi Sowal.com- I came on here from a link someone sent me about the talk about the septic tanks on the beach which really won't be a problem anymore beecause they will be protected from high water by this geotubes system. wanted to share some photos that some of my neighbors are putting in a t gulf trace. I know a lot of other owners are also going to do the same thing all along the beaches and they have been proven to work just fine in other places. This product is a series of textile bags that can be filled with water and then any color sand for a permanent application and covered with 3 feet of sand to prevent erosion of the dune and provide a restored dune. The sand can be cheaper dirt like seen in the photos cause it isn't going to be spread by waves or anything else. This method is really infailable. Thge Dep doesn't stop it like some other things like boulders or seawalls.
Isn't that Lee Perry's house directly behind the Geo Tubes?
EZ4144 said:
Wait a minute! According to the County Commissioners' most recent decision, only the emergency shore-up fill can be lesser grade sand, and even it has to be a 7.2 on the Munsell. All other sand has to meet an 8.1 level on the Munsell Scale, which would include the sand inside the tubes. That is only my interpretation. How do you think the new rules apply? Should this "dirt" also be tested to meet an 8.1? We do know that these tubes will break down or puncture, and spill dirty dirt along the beaches.
Smiling JOe said:
amen to the labelling, but I'd bet the house falls on it first, before it gets washed away. one or two good and nasty rainfalls should do it, then raze the collapsed structure and make them move to 660 feet away from any shoreline
if you want to know where all the sand went - just look to Mississippi's casino coast which now has a really pretty white sand shelf and Texas, especially around Galveston's barrier island complex, which grew about 2 miles in overall length. Even Dauphin Island in Alabama got a little bit longer. Big part of my job these days is eyestrain from staring at satellite photos.
marinebiology451 said:
Interesting...do you have any satellite photos to share?