A grain of sand

In the coastal town of Margate, New Jersey there is a battle going on. Like most battles it is for control of land. There are no armies or generals per se but what is won and lost is of utmost importance for both sides of the fight, beachfront property.

This fight is the outcome of an event that took place 3 years ago when Hurricane Sandy struck the east coast. The devastation to the coastal areas of Delaware, Maryland, New Jersey, and New York was immense, changing towns and the landscapes around them in just a couple of days. After the storm the recovery was lengthy and costly with estimates of damage as high as 50 billion dollars, even today recovery efforts are still ongoing. This storm was a wake up call to many on the east coast of just how vulnerable we are to hurricanes. Flood maps were updated, insurance companies altered policies; towns changed rules for coastal construction, and made plans to restore the beachfront. So what does this all have to do with Margate? It all comes down to dunes.

One of the hardest hit areas of Superstorm Sandy in Mantoloking, NJ. From:https://oceanservice.noaa.gov/news/weeklynews/nov12/ngs-sandy-imagery.html Check out this link to see more pictures of the changed coastline. From:https://coastal.er.usgs.gov/hurricanes/sandy/photo-comparisons/newjersey.php

Since Sandy was such a game changer for everyone, many questioned how we could protect ourselves against this type of damage happening with future storms. Is engineering surge walls or shoring up the coastline with dunes the best protection? Is the same technique appropriate in all coastal towns? What is the best way to spend resources, time, and money to rebuild communities? Questions like these fuel the debate, not only in Margate but also in many coastal communities. Of course, all these questions can become highly politicized which has hampered the process of getting anything done before the next big storm in many places. However, it might lend perspective to understand how many natural coastlines function against storm surges along the east coast. So let’s delve into what we know about the climate and geomorphology of the east coast shore, more specifically dunes

Dunes along the coastline of Delaware’s Cape Henlopen State Park.


I think it is safe to say that anyone who has been to the beach has experienced these two coastal constants, the ocean breeze and the unending cycle of waves crashing and receding. It is these physical forces that shape the coastline and it is how protective structures like dunes are formed and changed over time. The wind is a driving force for dune creation. Any coastal resident can tell you the cycle of wind along the shore; the breeze blows from the sea during the day and at night the wind comes off the land towards the sea. It is this constant wind cycle driven by diurnal temperature and pressure differences that provides the necessary wind conditions to push those tiny grains of sand in order to form dunes.

The climatic mechanism for the constant gentle breezes felt at the beach. From: https://climate.ncsu.edu/edu/k12/.breezes

If the wind is the creator of dunes then the ocean is the sculptor. Waves are constantly eroding the dunes; picking up sand from one place and depositing it elsewhere, shifting dunes and creating barrier islands. Just these two forces alone are enough to create two lines of surge defense; the barrier islands and the dunes take the brunt of the storm and protect the coast, ensuring water doesn’t move too far inland. There is also a third line of protection in these systems, the tidal marsh. In most cases marshes are equipped to handle the influx of storm water without it drastically affecting mainland communities.

Schematic of coastal systems, tidal marshes are part of estuaries systems. From: https://rustyfeagin.tamu.edu/tidal-freshwater-wetlands.html
A real world example of all the layers of protection in coastal communities. From: https://www.e-education.psu.edu/earth107/node/1012

So with all this natural safeguarding how are storms like Sandy so devastating? Quite simply, we are encroaching upon, building on, and often simply destroying all these lines of protection in our coastal cities. Instead of coastlines looking like this:

From: https://usfwsnortheast.wordpress.com/2014/08/20/the-view-from-above-an-aerial-tour-of-hurricane-sandy-recovery-and-restoration-sites-day-3/

We get ones looking like this:

Satellite image of the built up barrier island and tidal marshes near the New Jersey town of Seaside Heights.

They are so built up that all the protection, all lines of defense are compromised and we are the biggest losers. I’m convinced this problem is one of time. Humans experience the world on one time scale that is out of sync with geomorphic processes of coastline creation and alteration. The ground our coastal communities inhabit may seem like a constant during our lifetime but on a longer scale these land processes are always in a state of flux. Building up the coast seems logical due to the aesthetic of coastal living — there are opportunities to expand commerce, introduce tourism, and create residential communities. I am not arguing against the intrinsic value of these things but rather the “logical” conclusion of building on land such as barrier islands, which are ethereal by nature or tidal marshes, which are “designed” to flood seems silly if not downright dangerous. Especially when one big hurricane or nor’easter is enough to radically change the coastline.

Building permanent structures on impermanent substrates in my mind is very much akin to the sensation you experience standing by the ocean edge as the waves wash over their feet. Your feet are firmly standing on top of the sand and then the first wave rushes over your feet. As soon as that tide recedes you immediately feel the gentle tug of the water and the next thing you know the sand erodes from under you and your feet are engulfed. The longer you stand there the more buried they become as the sandscape changes around you. This happened to many homes in just one day on the Jersey shore during Sandy. They were inundated with water and the very foundations the homes stood on were undercut.


The good news is many towns and land management agencies along coastal communities are trying to support and bolster these natural communities in conjunction with engineered projects. While we may have understood for a long time that these natural barriers protect the mainland due to the combination of barrier islands, dunes, and tidal marshes that absorb the oceans energy, a storm the likes of Sandy has truly made us appreciate this fact all the more. This powerful lesson has put into motion big revitalization projects along the shore. Hopefully the idea of restoring some natural areas over time will take hold and people can enjoy the shore for decades to come without the impending threat of life and property loss.

For more examples and stories of recovery after Sandy check out this link: