To whom it may concern,
I am a coastal geologist, a retired James B. Duke Professor from Duke University. I have written a number of books on coastal hazards and beach processes on ocean shorelines as well as technical papers on problems created by seawalls and other forms of hard stabilization. One of the books was on the Lake Erie Shoreline (1987, Duke Press). I am pleased to have the opportunity to comment from afar, regarding the proposed hard stabilization of the Victoria Beach shoreline.
There is a great deal of experience globally with stabilization (holding in place) of eroding shorelines. The bottom line is that placing a seawall on a retreating beach will almost always cause the eventual total loss of the beach. The reason for this is that the seawall does not address the cause of shoreline erosion so the beach continues to retreat, getting progressively narrower until it disappears. When that happens the seawalls often have to be reinforced because the average wave height during storms increases when the beach is gone.
The time span required for beach loss is highly variable – months to decades. Since there seems to be little experience with hard stabilization there, there is no experience database on the rapidity of beach loss in front of seawalls.
Six US states (Maine, Rhode Island, North Carolina, South Carolina and Oregon) have outlawed seawalls although the issue remains a politicized one.
I would caution against use of experimental or temporary structures. One approach used in SC and NC has been to allow giant sandbags (provided they are removed after a couple of years), but enforcing the removal requirement has proved almost impossible and it turns out sandbags have the same impact on beach loss as concrete seawalls.
A second important impact of the revetment on Victoria Beach as proposed will be the loss of sand (and hence erosion) on adjacent beaches. As the beach narrows, the longshore transport system carries less and less sand until the sand transfer to adjacent beaches is halted all together. The seawall becomes a dam blocking sediment flow. The importance of this on Victoria Beach beaches depends on the volume of sand that is normally transported laterally by the wave-formed currents. On most lake shorelines this sand transport mainly occurs during storms.
A third “truth” about seawalls and revetments is that once you start you can’t stop. Seawalls always beget seawalls in large part because of the frontal and lateral erosion problem they have caused. In addition, once the barn door is opened and the legalities and objections overcome for one seawall, it is politically difficult for a governing body to turn down future requests for similar structures.
Thus on most eroding beaches, on lakes as well as along ocean shores, the long-range choice is clear. You can have beaches or you can have beachfront buildings but you can’t have them both. Perhaps the relocation alternative would be a better one, if survival of the recreational beach is deemed important to the community
Is preservation of a dozen houses worth it; houses owned by those who were imprudent enough to build next to an eroding shoreline? Is it the public’s responsibility to pay for this protection?
Another alternative approach besides moving buildings back is beach replenishment. This costly approach replaces the lost beaches with new sand either from offshore or from on-land sand pits. This is a perpetual expense once it is started as replenished beaches disappear much faster than natural beaches.
As I read the situation, this is a very critical decision for Victoria Beach. The community has reached a turning point and whatever choice is made, it will have a big impact on future generations.
Orrin H. Pilkey
James B. Duke Professor of Geology Emeritus
Division of Earth and Ocean Sciences
Durham NC 27708
919 684 4238
Orrin H. Pilkey
Phone: 919 684 4238
Orrin Pilkey is a research professor, James B. Duke Professor Emeritus of Earth & Ocean Sciences, and Director Emeritus of the Program for the Study of Developed Shorelines (PSDS) within the Division of Earth and Ocean Sciences in the Nicholas School of the Environment and Earth Sciences at Duke University.
Pilkey received his BS degree in Geology at Washington State College (he was a Missoula smokejumper during summers), his MS degree in Geology at the University of Montana and his PhD degree in Geology at Florida State University. From 1962 to 1965 he was an assistant research professor with the University of Georgia Marine Institute on Sapelo Island, Georgia. Since 1965 he has been at Duke University with one year breaks with the Department of Marine Science at the University of Puerto Rico, Mayaquez and with the U.S. Geological Survey in Woods Hole, Massachusetts. His research career started with the study of shoreline/continental shelf sedimentation, progressed to the deep sea with emphasis on abyssal plain sediments and back to the nearshore with emphasis on coastal management. He has published more than 250 technical publications and has authored, coauthored or edited 39 books.
In 2007, PSDS became a joint program with Western Carolina University. PSDS research continues to focus on beach nourishment, the impact of seawalls on beaches, evaluation of the validity of mathematical models of beach behavior, and global principles of barrier island evolution.
In 1987 he was awarded the Francis Shepard medal for excellence in marine geology and in 1991 he was the N.C. Wildlife Federation Conservation educator of the year. In 1992 he became an honorary member of the Society for the Study of Sediments (SEPM) and was awarded the George V. Cohee Public Service Award by the American Association of Petroleum Geologists. In 1993 he was awarded (jointly with William Neal) the American Geological Institute award for outstanding public communication. In the same year, he received the Jim Shea Award for Public Service from the National Association of Geology Teachers. In 1999 he received the Outstanding Public Service Award from FEMA. In 2000 he was awarded the Geological Society of America’s Public Service Award. The Priestly award was granted in 2003. In 2008 he was awarded the Lifetime Achievement Award from the NC Coastal Federation. Previously he was president of SEPM, the Society for Sedimentary Geology, president of the North Carolina Academy of Science, a member of the council of the Geological Society of America, and editor of the Journal of Sedimentary Petrology. He is co-editor and sometimes co-author of the ongoing 22 volume, state specific Living with the Shore series published by the Duke Press, as well as two 1996 volumes: The Corps and the Shore (Island Press), Living by the Rules of the Sea (Duke Press), A Celebration of the Worlds Barrier Islands (2003)m How to read A North Carolina Beach (2004) and Useless Arithmetic (2007). He has also been featured in New York Times Magazine, Esquire, Oceans Magazine, The American Way, Fifty Plus, Smithsonian Magazine, Der Stern and The Chronicle of Higher Education.