Chapter 3

 I recently retired after a 32-year career, 30 of which I worked for the Federal government. Most of my Federal time was spent working for the U.S. Geological Survey. I loved my time at the Survey. I worked with a fantastic group of people on a fantastic journey to predict what hurricanes would do to our nation’s coastlines. I often saw the impact of many of these storms before. The diversity of the changes along the shore when one of these storms made landfall were varied and heartbreaking, for individuals as well as the environment. And yet, Nature always recovered, or she found a new path. Her resilience is inspiring and beautiful to watch. She doesn't bemoan the loss of a marsh buried in sand or the break in an island. She returns to the path she was on, or creates a new one. It is we who build our castles and expect them to last forever. 

  A barrier island is, by nature, designed to move. It rolls over upon itself in retreat from storm surge. Sand from the beach or dunes is washed over the island and deposited in a new location. That new deposit becomes habitat for new communities. A loss in one location becomes a new beginning in another. Nature will adjust to the change and continue on. It will do the same as sea level rises. It has always shifted; it will always continue to do so... or at least try.

 It is only when we build fixed structures on our coastlines that we realize how truly dynamic this system is. We build castles on sand dunes and expect the sea to leave them untouched. It doesn't, and it never will. To believe it will do so is a fool's errand. Our planet is dynamic and the ground we stand on is always shifting. We can't always perceive that shift, but at our coastlines we can often see the changes right before our eyes. Sometimes year to year, sometimes in the blink of an eye.

  We can learn a lot from Mother Nature. She is fickle and ever changing. Our lives, like the ground we stand on, is ever shifting, no matter how much we wish things were the way they were before. We don't always recognize the change as it happening, as it is usually slow in most places. But sometimes the change is sudden and catastrophic. And when that happens, we sit up and take notice.

  

  Sometimes it’s hard to keep up, to find that steady ground on which to stand and catch our breath, to find our center and get our feet beneath us. Technology changes are coming at an ever-increasing speed. Political changes are sometimes faster than, or not as fast as, we'd hope. The climate is changing in ways we can't fully predict. Knowing and excepting things will not always be the way they were will help. If we learn not to build our castles on sand dunes, we will be more resilient, and recover more quickly from change, planned or not, in our lives. 

  Why Chapter 3? We like to divide our time into segments, be that our day, our week, our year, or our life.  

  I see the first chapter of my life as the time from when I was born until I graduated from college. It was a time of learning, and growing. A time when everything was new and changing. It was what I expected and I shifted with those sands easily.

  Chapter 2 spans my working career. I didn't change jobs as often as most people and sometimes resisted it. I started by working for the Department of Defense right out of graduate school, worked a short time in private industry, then returned to the Department of Interior for nearly 29 years. My time there, with the Survey, was always changing and evolving. Each year brought new challenges and changing times. No two were the same. Those who were there before me left, and new faces joined the Center. Times were busy and times were slower. The work was always interesting and carried with it the satisfaction that I was doing something that helped protect lives and property by understanding what had happened in the past, and using that knowledge to predict what would happen in the future. But as steady as those sands have been, the sands there were shifting, too. 

  It comes down to this: My sands, our sands, are shifting. The work at the Survey will continue, just as a highway continues across the landscape. I have chosen to exit the ramp presented to me. The sign beside the road says "Chapter 3" and points in a different direction across a landscape we've not traveled before. The work at the Survey is no less important because I have stepped aside. Many capable and talented people will continue on. My path is a different one now, though I will continue to follow their progress for a long as I can see them, and that will be a long time indeed.

  Edward and I have planned for this for some time. We have set out on this path perhaps a little earlier than others before us. We are ready. The ground is by no means completely solid, but we hope it will be more like the Rockies then Jockey's Ridge. We have set out guide posts to help us on our journey, we have our walking sticks to steady ourselves when we encounter the unexpected, and we are ready for this next chapter in our lives.

"Two roads diverged in a wood, and I—

      I took the one less traveled by,

      And that has made all the difference."  - Robert Frost  

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A Simple Model of Coastal Erosion...

The USGS holds an Open House every November. We set up booths with displays to show our research to the public and try to present it in a way that everyone can understand.

The display I run is called The Wave Tank.

The Wave tank was a shallow pan with about 1-2 inches of water in the bottom. At one end is a shop fan, the type that can move a lot of air in a small space. In the middle of the pan is an island, built from playground sand, and green and brown colored sand from Micheals. The colored sand helps define the island surface and show the erosion as the model runs. I usually build the island like a dog's toy bone, thick and high on the ends and thin and low in the middle. On a real island the sand piles would represent dunes. On top of the dunes I place houses built from small wooden cubes, some with nails in them to represent pilings, others without nails. They are stuck into the sand at various levels and places. It represents a typical barrier island, one you can find along much of the East and Gulf coasts of the US. At the back of the pan there is another pile of sand, which represents the mainland behind the barrier island. It's a surprisingly simple representation of a coastal system and I use it to show what can happen during a hurricane.

When I turn on the fan, the effect is almost immediate. This simple model begins to erode within minutes. The whole thing takes about 60-90 minutes to run and shows several import coastal processes that occur during a storm. First, a scarp forms on the front of the island, and the sand begins to move from the front of the island to the sides. This demonstrates the natural sand transport that is always occurring on the beach. A small flat shelf of sand develops in front of the island as the "dunes" erode.

If you look close, you can actually see the sand grains moving along that shelf. Sometimes, when the houses aren't completely stuck into the sand, they'll blow over. That's OK, because damage to coastal structures isn't always caused by water.

When I build the island, I put a layer of brown sand inside the island. The neat thing about the brown sand is that, for some reason, it doesn't like to absorb the water. As it turns out, this is a good thing for the model. The brown sand traps air and behaves the same way a layer of muddy, marsh sediment would behave, acting at first like a resistant layer to erosion from waves. It makes the dune scarp more pronounced and for a short time protects the island from eroding.

As the storm continues to blow more sand is removed from the front of the island and transported to the sides, where spits form. In the center, where the surface is lower and narrower, the island becomes dangerously thin.

On the ends, the brown sand has been exposed and the overlying layer sides off into the water, taking the houses with it. This sand becomes an additional source of sediment for the growing spits. The houses on top of the sand, with pilings beneath them might tip or fall into the water.

This year, as an added twist, I built a seawall of small stones for a few of the runs. Behind the seawall, things are better, but only for a while. Waves refract around the seawall and begin to erode the dunes from the sides. In fact, in one run during the open house, the side of the island with the sea wall actually eroded faster then the side without at first, due to the action of the waves around the seawall. Eventually, the unprotected side lost it's battle while some of the island with the seawall remained protected. It showed that the seawall wasn't the solution to the problem of erosion and in some places made the erosion worse.

The model also shows that just because it had pilings didn't mean a house will survive. If they aren't blown over by the initial gusts of wind from the fan, they still had to deal with the erosion, overwash and undermining of their supports. If the pilings were long enough to push all the way through the sand to the bottom of the pan they might survive. Sometimes, a house that started at the top of the dune ended up standing in water, with no land around it anymore. If the pilings were too short, then it was only a matter of time before the sand would erode away, and the house would fall over.

Eventually, the center of the island breaks through, forming a breach. Sand from the two now disconnected islands is transported through the gap and an overwash deposit is formed. My once tall pile of sand has flattened out and changed shape.


I reset the model three times during open house. Sometimes with a seawall, once with a breakwater in front of the island, but not touching it. No two runs are ever the same. Sometimes the island erodes quicker, and sometimes slower. If the island is closer to the fan, it erodes faster, just as if the hurricane were a stronger storm. In our model we see scarps form and underlying "muds" exposed, dunes washed away and structures fail, we see islands breached and islands overwashed. All these things we see in nature, all these things we see on real islands in real storms, on real coastlines.

The first time I ran this model was in Reston, VA, for the USGS Open House at the National Center. I wasn't completely sure at the time if it would work. Oh boy, did it work! The kids not only loved it... they got it. Would you like to live on a barrier island?... "No..." Why? "Because it's going to go away." Where would you like to live? "Back here" they say pointing to the sand at the back. A father looked at me and said "Now I get it." One boy was particularly excited. He explained what he thought was going to happen to his Mom. And he was right. Then for the next hour, he returned about every 10 minutes, Mom in tow, to check the process. With each visit he pointed out what had changed, and which houses were closer to falling over, and which ones had. This year, in St Petersburg there was girl who returned again and again to check the progress of "her" house, the one she'd picked at the start of the run, to see if it was still standing.

It's a simple model, but it works. Over the course of an hour, I can show someone what might happen to a house built on a beach. I can show them what might happen to the island itself. A beach, or a barrier island, is a pile of sand. It is, by it's very nature, designed to move. Putting seawalls and riprap in front of a structure to stabilize it only delays the inevitable. Water moves sand. Wind moves water. In a hurricane the sand is going to move. A barrier island not a place you want to be during a storm. It's not hard to understand that. And maybe, just maybe, we really should be considering if we should be building out there in the first place.

Island Animation - Click to play (660kb)