Thursday, February 4, 2010

sandbags on the beach.

As you know, SF Surfrider and Save the Waves were pushing for the use of sandbags (technically called sand-filled geotextile tubes/bags) along Ocean Beach at Sloat Blvd. over a rock revetment. Though the use of geotextile bags may be common on some sections of America's coastline (ex. Texas and North Carolina) they are not that common in California.

On Surfrider Foundation's website page Coastal A-Z geotextile tubes are defined as "elongated cloth bags or tubes made out of plastic material that can be stacked or arranged as a form of semi-hard coastal engineering." These sandbags are HUGE HUGE bags that are filled with sand and placed along a eroding coastline or in the wave zone to build up an offshore berm (reduces wave action).

"Hard" structures are riprap revetments (rock on beach) and seallwalls. "Soft" sturctures includes beach nourishment and coastal retreat. The geotextile tubes are known in the coastal management world to be in between "hard" and "soft" structures - which leaves the use of geotextile tubes in a grey area.

Bottom line is: (1) in some cases, Surfrider Foundation Chapters around the nation are against the use of geotextile bags because sometimes the bags are SO big and the casing is SO thick that the very very durable sand-filled sacks will never leave the beach system - and often the bags are placed in the water as a groin (see Florida Suncoast Chapter's website) or as an artificial reef; (2) there is not that much information out there about using the geotextile bags for shoreline erosion control (send us info if you have it); (3) i have always been told that the "sandbags" can have the same effects as seawalls etc (but this is probably because sometimes cement is added to the sand inside the sandbags and create "concrete bags"); and (4) however, one obvious positive side to the use of sandbags is if they are designed right, they can be easier to remove from the beach than rocks.


PICTURES:









North Carolina Beach.
http://beachcare.org/_img/issues/beach-armoring/massive-sand-bags.jpg









Southern California Beach.
http://malibusurfsidenews.com/blog/uploaded_images/DSC3681sandbags-766329.jpg



REFERENCES:
(1) One of the ONLY articles on Geotextile Bags: Coastal erosion prevention by geotextile tube technology by E.Shin and Y.Oh
(2) Info on Coastal Armoring (not including geotextile bags): http://www.kqed.org/w/coastalclash/armoring.html
(3) website for a geotextile company with good photos:
(4) Info on shoreline armorning (looks like North Carolina allows sandbags as a tempory fix): http://www.surfrider.org/stateofthebeach/08-fc/body.asp?sub=ShorelineStructures
(5) Info on alternatives to shoreline armoring: http://coastalmanagement.noaa.gov/shoreline.html
(6) Info on the use of geotextile tubes in Texas (Texas considers geotextile tubes to be "hard" sturcturs): http://www.surfrider.org/stateofthebeach/05-sr/state.asp?zone=GS&state=tx&cat=ss

Please let me know if you have any other good information on the use of sandbags on the beach for coastal protection.

If the bags were to be used along Ocean Beach, SF Surfrider would only support them for temporary fixes. A long-term solution to the erosion problems at Ocean Beach is what is essential.

14 comments:

  1. I am currently installing sand bags in the Outer Banks. at first I had reservations about this process, however after riding out last nights extreme beach erosion high winds ang tremendous surf I am delighted with the result. this process does not have to be temporary, with proper maintenance this type of defence can withstand time done properly. Maybe I am having great results due to my bag design. The downfall to this is inconsiderate people who have no respect for other peoples property and vandelize the bags. The fix to that is survalence cams.

    ReplyDelete
  2. I would recommend the following books:

    "The Beaches are Moving: the Drowning of America's Shoreline", by Wallace Kaufman and Orrin Pilkey.

    "The Corps and the Shore", by Prof. Orrin Pilkey

    "Against the Tide", by Cornelia Dean

    I would also suggest with no disrespect that the "great results" (comment from EUNICE)from sandbags will ultimately, if left in place, cause more damage and erosion.

    rule of thumb: for every meter of horizontal land that is "protected" by coastal armor (hard or soft), a meter of vertical beach is lost.

    ReplyDelete
  3. Just to clarify,

    Surfrider was advocating sand bags to be used for the emergency situation - a temporary fix to be removed after the winter season - when sand nourishment work could begin...

    ReplyDelete
  4. steven know these books i will rec 2

    ReplyDelete
  5. I recently came across your blog and have been reading along. I think I will leave my first comment. I don’t know what to say except that I have enjoyed reading. Nice blog. I will keep visiting this blog very often.

    ReplyDelete
  6. This blog is absolutely amazing!!! i must to say i enjoy a lot every time that i go to the beach this area make feel very relax and comfortable.And i prefer to go at the beach with my boyfriend and enjoy together. In fact he buy viagra with the object to find a way or solution to his problem. But the most important thing is that we can enjoy together.

    ReplyDelete
  7. Nice blog, I really enjoy very much every the time when i go at the beach. Actually i will go frequently after to prove costa rica investment opportunities , i hope my travel at the beach can be possible.

    ReplyDelete
  8. Nice blog, I absolutely get pleasure actual abundant every the time back i go at the beach.miami beach condos

    ReplyDelete
  9. Karthik Geotextile's portfolio covers different array of Technical Textiles like Geotextile Fabric, PP Woven Fabric, woven geotextile etc.

    For more info : Geotextiles UK

    ReplyDelete
  10. Suruchi Technical Textiles is a top quality producer of technical textiles.


    For More Info: Geo Textiles

    ReplyDelete
  11. AFFY Techtex Trade India is the manufacturers of woven geotextile, geo textiles, pp woven fabric, geotextile fabrics and groundcover suppliers in uk

    Geofabrics

    ReplyDelete
  12. Flint Industries has extensive experience in coastal protection. For detailed information on its TitanBag and TitanTubes, go to their website at www.flintusa.net.

    ReplyDelete
  13. Nice blog post If you are searching for the quality Bitumen EmulsionBitumen Emulsion is bitumen and water emulsified together to create waterproofing and roading binders that are environmentally friendly.

    ReplyDelete