Let me start off by saying sorry if this is not well put together and hard to read. I’m still working on formatting these posts in markdown how I’d like them to be. (tl;dr at bottom).
In my three years as an undergraduate student studying marine science, marine geology has been one of my favorite subjects to date. While doing research and writing a paper for my marine geology honors lecture I noticed that coastal erosion is more prevalent in areas where we have tried to stop erosion. It's true that erosion can be contributed to rising sea-levels from the warmer weather creating higher sea-levels and stronger storms (see this past hurricane season). But that's not what I'm necessarily focusing on in this post. The point of this post is to focus on why trying to save beaches and other areas from erosion may cost more than what it’s worth.
Coastal Structures
If you ever go to the beach you may see a jetty, groin, or a seawall. A jetty is a long protruding structure that stretches from land to sea and is usually made up of stone or concrete but can be made of numerous things. Jetties usually come in pairs of twos and typically are found at the mouths of inlets. A groin is similar to a jetty in that it stretches from land to sea, but it is typically used as a way to preserve small areas of the beach from erosion and is found in a "row" of at least two. A seawall is just that, a manmade wall to block the sea from coming in. Seawalls let the water come in still, they're just meant to absorb most of the impact of waves to limit the waves' energy when it hits the beach. In theory and in practice, these work exactly how they should but with a few setbacks that could potentially be costly.
Let's Talk Beach Erosion
While it may seem like a good thing that we protect beaches from erosion with the previously mentioned structures, it might not be the best thing. If you have seen a jetty or groin at the beach you may have noticed that the side of the beach that the side that is blocked from longshore transport (the transport of sediments along the coast) has significantly more sand than the other side of the beach (see image below).
Image source
The above image is a perfect example of how jetties, groins, and a seawall can impact the beach environment, it shows how sediment is deposited along the coastline behind the groin and how it is eroded even more in front of the groin. It also shows how the adjacent beach is eroded even more than just a groin by itself due to the seawall. Erosion due to seawalls is called “flanking erosion.”
This so-called "flanking erosion" takes place at the ends of seawalls. Wave energy can be reflected from a seawall sideways along the shore, causing coastal bluffs without protection to erode faster.
Beachapedia.org
The excerpt above explains what happens in a more straightforward way than I could.
If you’re a beach lover like I am, you would prefer a beach being there when you go to the ocean. If this erosions keeps occurring at this higher rate, due to the aforementioned barriers, there will be no beach left to visit. To fix this, local governments typically re-nourish the beach. The easiest and fastest way to do this is by finding similar sediment on the seafloor, suctioning it up, and essentially shoot it onto what’s left of the beach. The only thing left to do after that is to get the sand where you want it and be done with it until a few more years down the line. But most places that do this type of beach re-nourishment have to keep going further and further away from the coast to find similar sediment; this makes it more costly to re-nourish beaches in the long run and has a great impact on the sea life in those environments. Once the re-nourishment starts, all kinds of sea life are sucked up, shot on land, killed, and even lose their home environment but that’s a little off track.
If you look at untouched beaches, the rate of erosions is much slower than the beaches where we see the barriers at. This leads me and many others to speculate if it’s even worth it to keep building these barriers or just let them go and let nature take care of itself. The beaches are good for business, but the greater difficulty in finding sediment and cost of building and maintaining these barriers will eventually outweigh the profit, especially if sea-level continues to rise.
An example of an untouched beach would be Watie’s Island in South Carolina (click here for a google view of it). There has been no development on this beach and the erosion rate here is much slower than on the neighboring Cherry Grove Beach where just a month ago they underwent beach re-nourishment in order to keep tourists coming in and to protect the hotels on the beach.
What do you guys think we should do in order to counteract the erosion on beaches to preserve local economies as well as preserve the ecosystems that exist there already?
TL;DR:
Coastal barriers to prevent erosion are likely causing more harm than good. We should stop maintaining barriers and stop re-nourishing beaches before the cost of doing so is more than the money from tourism. Beaches should be left alone and let nature do its thing.
This is my thoughts on the matter, not an experts’ thoughts on the matter. I didn't want to go too in-depth on the matter but can if anyone wants me to. This basically just seems like a bunch of claims with no resources to back it up as of this post.