i'm interested to know your personal experiences/opinions on jetties, specifically around inlets. the reason i ask, is that Ocean Isle Beach NC is expecting to install a jetty on the west side of the Shallotte Inlet, between the beaches of OIB and Holden Beach, probably within the next 5 years. we've always had erosion problems on the tips of our island, which wouldn't matter too much, but that's also where we've got people with homes. the extreme eastern end of the island (where the jetty will go) has about 10 homes at the moment where the high tide mark is now encroaching under the foundations of houses. these homes reside on third street, because first and second streets no longer exist; they're a 100 yards out under water actually.
as far as i know, the legislation has passed and we will be getting this groin. right now, the state is supposedly "inspecting" the area to better understand how they will go about installing it. i believe it will be just one structure on the Ocean Isle side of the inlet, without a companion jetty on the Holden Beach side. i would prefer that the beach stay natural, but... whatever.
so i'd like to ask for your opinions on jetties and what's been your experience in dealing with them. have they performed as they were intended? pros/cons? the sand next to them is stabilized, but way down the beach at the next inlet has taken a turn for the worse/better? i'd appreciate as much response as possible. thanks
i would be surfing right now, but it's not 23 feet yet, so it's tough to get motivated for these sissy waves... maybe later.
Results 1 to 10 of 18
May 5, 2013, 02:15 PM #1Member
- Join Date
- Mar 2013
opinions... are jetties good/bad/necessary?
May 5, 2013, 02:26 PM #2
While you could make some generalizations about what the likely effects of the jetty will be, every spot is different, and results will vary. There are a lot of factors, and all of them need to be considered when a structure is designed and constructed. Whether or not the engineers have "done their homework" is the question, and if I was someone in your position, I'd be asking a lot of questions. Projects like this often have public comment opportunities, and I'd be sure to take the opportunity to get some details.
May 5, 2013, 02:31 PM #3
Charleston harbor jetties caused rapid erosion of Morris Island, along with addition sand loss on Folly. In that case, I would say they were bad. There are examples out there where they are good.
May 5, 2013, 11:46 PM #5
May 5, 2013, 02:41 PM #6
- Join Date
- Jan 2009
- Hilton Head Island - OB, SD
I would say regardless of the effects on the surf, that particular jetty seems necessary. Regardless of if you live in the SE or the mid-atlantic, all these sandy barrier islands are on a time clock. Without installing jetties, pumping sand etc, these areas would or will no doubt become unlivable. So for the local economy's sake, not to mention the millions of coastal home owners up and down the coast, these Jettys are very important and usually do what they were intended to do... My dad used to always say, some day in 50 years, Ocean Pines (OC MD) will be the new ocean front... It was a half joke, but it is what it is... Most of the coastal areas in the Mid-A and SE are not ideal to populate with structures and people. We all know this... Same goes for HHI where I live... Any season, this place could get ripped in half again the same way it did early in the last century... Same thing happened to OC MD way back in the day... Same thing happened dozens of times in the carolinas... OBX etc.... We are all on borrowed time living in these regions, so sometimes I try and put my surfing aside and accept what is best for people living in my area...
May 5, 2013, 03:16 PM #7
- Join Date
- Jan 2009
- milton delaware
Inlet jetties are necessary when we develop too close to natural barrier island inlets. Warning: Huge Generalization: Barrier island inlets are naturally migrating features that send to move in one direction for a while (driven by net littoral sand drift), until the bay or river is taking such an inefficient path into the ocean that a storm cuts a more efficent and direct route and the migration process begins again. This is obviously a fluid landform that just begs to be avoided with immovable development. Jetties are mans way of stabilizing the inlet to hold it in one place, and end the perpetual migration.
In the illustration below, the likelyhood is a new inlet forming during a storm up around the 1738-1808 location, and with that new more direct water flow the 1987 inlet will silt in and close. Can you believe this is the kind of landform that we have chosen to develop? Amazing!
Last edited by mitchell; May 5, 2013 at 03:21 PM.
May 5, 2013, 03:40 PM #8
Johnny: The Masonboro Inlet jetties are a good case study for what you might expect to happen with the Shallotte Inlet. I'm pretty sure they will end up going with a jetty on both sides eventually because it's the only really navigable, deep water inlet in the HB/OIB area and needs to remain that way.
Put it this way, the waves on the North End of Masonboro would not be nearly as good if the jetty wasn't there. The inlet has caused shoals to form offshore there, the bathymetry tends to bend the waves into the nice peaky lines that spot is known for... sort of the same effect that makes Duranbah (around the corner from Snapper Rocks) such a world class beachbreak.
The MBI jetties are also great for fishing and spearfishing thanks to the crystal clear water we enjoy in this area, although the water is usually too brown around OIB to make for good spearing visibility you will still be able to land some doormat flounder around it.
In 1933, there was a hurricane that created the Ocean City inlet in a matter of 36 hours...a jetty was built a year later at the new end of Ocean City. Before the hurricane, Ocean City and Assateague were connected. Since the building of the jetty, it has prevented the natural flow of sand south to Assateague, and the island continues to diminish and push further towards the mainland.
"The jetties were constructed by the Corps of Engineers in 1934, after the inlet formed during a
major storm in 1933. Since it formed over 60 years ago, the inlet has functioned as a
thoroughfare for boating traffic between the ocean and the coastal bays. In addition to
providing access to the coastal bays, the jetties have disrupted the sediment supply
between Ocean City and Assateague Island. Prior to the formation and stabilization of the
inlet, the sand generally traveled from Ocean City south to Assateague Island. Since
construction, the inlet and jetties have prevented a large portion of sand, which would
otherwise have reached Assateague, from reaching the island. Consequently, the northern
11 km (6.8 miles) of the island shoreline have been seriously affected. The disruption in
the natural longshore transport of sediment between Ocean City and Assateague Island
has resulted in adverse physical, biological, and economic impacts to the area. The result
is an island that is not being maintained in a natural condition and that lacks the geologic
integrity of a healthy barrier island. A substantial portion of Assateague Island, which has
always been known for its natural beauty, has also suffered significant aesthetic impacts.
The island overwashes frequently, and the shoreline has eroded back towards the mainland
at an accelerated rate. This erosion has caused a loss of salt marshes, an infilling and
reduction in size of Sinepuxent Bay, and a decrease of habitat diversity on the island. It
has also created navigation difficulties near the inlet and through the back bays, and has
increased the vulnerability of mainland communities to storm damage.
Due to the lack of an adequate sediment supply, it is expected that northern Assateague
Island will continue to be degraded, and a breach will most likely occur on Assateague
Island, which could cause additional inlets to form. This could occur during the next
substantial coastal storm. An additional inlet would change the dynamics of the area and
would create more environmental and economic problems. Most importantly, the
Assateague Island National Seashore, a national treasure, would suffer significant loss. In
addition, it is expected that considerable losses to wetlands would result, as well as losses
to recreational opportunities, damage to property, and hazards to navigation."
excerpt from http://www.mdcoastalbays.org/files/p...ix-d_Part1.pdf
This article shows pictures of the aftermath of the storm and a picture that shows how much Assateague has moved since 1933....http://www.baltimoresun.com/news/mar...3.photogallery
Jetties have their pros and cons, there will be changes to the coastal area, no doubt. Anytime, we try to control or inhibit the ocean and land from it's natural progression, we can expect it to backfire in our faces. I'm just glad that I won't be around to see Assateague fall off the map, fingers crossed.
Last edited by Koki Barrels; May 5, 2013 at 05:23 PM.
May 5, 2013, 06:50 PM #10
Sounds like they need to have a bypass pump in that case, Koki. I think something like that would help out at most jettied inlets.
For the record, I am a proponent of jetties protecting navigable inlets.