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.