The Louisiana Berm: A Coastal Fix or an Introduction to New Problems?by Orrin H. Pilkey | June 29th, 2010
posted by Erica Rowell (Editor)
Sand berms. Louisiana’s governor has promoted them; others have cautioned against them. Which side is stronger, the pros or the cons?
To create the berm, sand needs to be pumped from nearshore locations a la the process used in beach renourishment projects like the one shown here. (WikiCommons)
Promoting the placement of small ridges of sand, or berms, in front of selected barrier islands along the rims of the Mississippi Delta has been a very political process pushed by a state government anxious to try something — anything — to mitigate the environmental disaster thrust upon them. But sometimes doing something is worse than doing nothing.
The project got underway earlier this month. Then in the last few days it was stopped at least for the moment. I believe that the outcry from the scientific community was one reason and I suspect the economics of the project became more and more untenable. But then yesterday, dredging started up again.
For weeks, Governor Bobby Jindal has energetically promoted the use of sand berms as a means of coastal protection.
In late May the U.S. Army Corps of Engineers approved a six-section, 45-mile-long berm that will be 300 feet wide and extend six feet above the mean tide line (the state’s initial request for 128 miles of berm might yet be permitted).
The White House approved the project in early June.
BP agreed to pay the estimated $360 million for the initial berm — a cost projection that, based on pre-determined nourishment costs for reconstructing barrier islands, the Interior Department believes is a bit optimistic.
Last Tuesday the berm project was temporarily halted because of a missed deadline to stop dredging in sensitive areas that could create erosion issues for the Chandeleur Islands. (NASA)
By mid-month, dredging work began.
The Idea Behind the Berms and Their Potential Problems
Since its proposal, the berm has been fraught with uncertainty, and it’s clear that few coastal scientists believe it will work (see here, here, here and here). Here’s a look at what scientists see as potential hazards surrounding the project.
Where to site the berms is an important step. In general, placing the sand on the islands proper would not work, as doing so would destroy animals, birds, and bird-nesting environments that are among the very things the berm aims to protect.
Instead the sand would be placed in the surf zone in front of some of the narrow, low-lying barrier islands. The idea is to prevent the oil from coming into the marshes by letting it pile up on the sand berms to be cleaned up later.
The creation of a steep slope would hasten erosion. The placement of the berm will produce an offshore slope ten times steeper than the natural one. Such a steep slope will allow less wave friction with the bottom and increase the average wave size striking the beach. The result will be rapid erosion even without storms.
More dredging and additional time will likely be needed. The proposed offshore dredging site contains a very muddy sand. As a consequence, more dredging and more time will likely be required to get a true sandy berm in place.
Storms pose multiple problems. Sections of the berm that block tidal inlets will almost certainly be re-opened by the first small storm to hit the coast. (Inlets are needed to “drain” fresh water influx as well as tidal exchange. If the inlets are closed up, nature quickly makes a new one!)
The berm can and probably would be quickly removed by storms. It wouldn’t take a hurricane to do this. Waves from a small tropical storm well offshore could do the trick, and the sand from the berm (probably mixed with a lot of oil) could then be expected to be pushed ashore and cover the bird-nesting areas that are supposed to be protected.
If a hurricane comes ashore, the berm would play almost no protective role, and oil spiked ocean water would penetrate miles into the marshes.
The bottom line is that the berm probably won’t be done in time to help with this oil spill, nor will it remain in place for the next one.
Do the scientists and engineers who are skeptical about the project have a better idea? Unfortunately, there is no silver bullet to solve this horrendous environmental problem. There is no good fix to prevent oil from washing up on the shorelines and into important wetlands and marshlands. So why spend a huge amount of money on a project that will likely make little difference and may even create further problems?
A Possible Silver Lining
Among the numerous problems created by the berm is one that may dramatically affect the U.S. East Coast. The effort to make a 45-mile-long (or perhaps longer) berm would require using most of the available American dredges, especially if it’s to be built quickly. This means that the cost of nourished beaches this year and perhaps for years to come would most likely skyrocket, and probably a number of planned East Coast nourishments would be canceled.
In some ways this might be a harbinger of things to come for East Coast beach communities. As sea level continues to rise, beach nourishment will become less and less fea
sible because of diminishing sand supplies and increasing rates of beach loss. A few years without beach nourishment might precipitate some community thinking about the future and the need to prohibit more hi-rise building and to move some buildings back from the shoreline. In that case something very good could come from the berm project!
Bill Chameides is on vacation. He will be back in two weeks.filed under: ecosystems, faculty, guest, oceans, oil, policy, politics, science
and: beach, Bobby Jindal, BP, Deepwater Horizon, Deepwater Horizon oil rig disaster, dredging, Louisiana, offshore energy, oil spill, Orrin Pilkey, sand berms, wetlands