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)

The Fly...

I know what a fly feels like when he lands on fly paper...

Back in February, they disassembled the cube farm outside my office, pulled up all the carpet and installed new carpet squares. These were supposed to be great because if one square got stained or worn, you could peal it up and replace it, without disturbing it's neighbors, the desks or have to replace the whole carpet again. And believe me, after 13 years that old carpet needed to be replaced. Once they were done, office installed brand new cubes, providing more seating then before. Sounded great...

About 3 months later we all noticed that something wasn't quite right. The squares were starting to curl up. Our operations manager said that when the carpet was made, they recycled the backing material, in an effort to be "green". Unfortunately, some silicon contaminated the rubber backing. And you know what silicon is used for, to provide lubrication or... (wait for it...) a non stick surface. The problem is that in this case, they wanted a "stick" surface. Because the carpet squares were pealing up, people were tripping on them... people carrying computers were tripping on them... not good.

Even better, we weren't the only office to be carpeted with that particular lot of carpet squares. Two other offices in St Petersburg were in the same situation. The solution, pull up all the carpet and redo it. To do that, at least in our case, they had to remove all those new cubes first.

Tuesday and Wednesday we spent time moving all the people in the farm out of their cubes (again), and into other seating. Thursday, the cube installer returned, disassembled all the cubes and stacked them to one side off the carpet. They had to do it, or it would void the warranty. It took them about 6 hours. Now the interesting thing is that with the cubes removed we all noticed the "new" 8 month old carpet squares looked like they were about 8 years old, very worn and faded where people sat. Strike two for this batch of carpet. Friday morning, starting at 8:00 am, a crew removed all the old carpet. I can say with certainty at this point... it wasn't the carpet glue that was bad.

I had enough foresight to wear sneakers on Friday. I thought about it before work. If I'd worn my Birkenstocks, they would still be over by the entry to cube farm, stuck in the glue. Even with sneakers on, the glue threatened to pull off my shoes... People who wore flops were walking out of their shoes. It was an amusing sight, actually, watching them struggle to keep their shoes on their feet. More people had worn flops then not.

Think of walking through a puddle of dried sugar. You know, someone dropped a popsicle on the sidewalk two days ago, and you walked through the remains and your shoes feel like they are sticking to the ground. Now imagine that 10 times stronger... no, 20 or more times stronger. To get to my office I have to walk, at a minimum, 30 feet across this glue. What's more, like that stickiness from the popsicle sugar stays on your shoes for a little while, and so was this glue. It's the stick that keeps on sticking. Next thing I know, I'm sticking to the tile, my office carpet and everywhere else I walk..., skerch, skerch, skerch... you can hear me coming. And it hasn't come off yet, two days later. I drove home barefoot on Friday, because even though I scrapped, scuffed and shuffled my way to the car, it wasn't coming off any time soon and I didn't want it on my pedals.

This weekend the carpet company is supposed to re-lay all the carpet. The cube installers are supposed to be back on Monday to reassemble the "farm". Then everyone is supposed to move back to their appointed places. I hope that is the case, because walking on that glue is been super annoying. None of us thought they wouldn't start laying the new carpet as soon as they pulled the old carpet up and I didn't figure they would pull the carpet until they were ready to start re-laying it. Silly me.

I think the carpet company may have realized their mistake, or at least they were aware of it, in pulling the carpet up on Friday Morning, instead of stay... Friday afternoon. About 3:30 I noticed a strange woman struggling across the glue in backless pump-style shoes. From the door of my office I asked if she was looking for someone. "Nope, I'm from the carpet company. I'm just bring up this box..." which she then decided to toss to the side by the wall, into the glue, and head back the way she'd come. I couldn't help but smirk as I watched her struggle to turn around, and make her way back to the edge of the glue without loosing her shoes. 15 feet and about 3 minutes later she made it. All the while looking like a fly caught on sticky paper.

Lemon Light...

There was a storm approaching.... The radar was showing bright red just east of us. About 30 minutes ago it started rumbling, quietly at first, then progressively louder. The sun was also setting, and as it did, it got below the edge of the clouds to the west and the whole sky lit up with lemon yellow light. Beautiful and erie at the same time. Greens became richer or darker, depending on the tree or plant or grass. The cedar took on a rich, dark green hue.

I wandered out to the end of the driveway to watch the sky. Off to the east, in the direction of the approaching storm, low scud clouds were standing out against their darker comrades as they raced west. Lightning began to stand out against the darkening sky. The rumbles got louder. From the east, the winds picked up, carrying the telltale signs of approaching rain. Cooler temperatures and the feeling of more moisture in the air. It was time to retreat to the front patio.

The sky began to fade. But then, the sky turned orange. The greens became muted, and the lightning more frequent. It was starting to rain.

I retreated into the house to watch the rest of the storm. We sat in the front room with the lights off. The frequent lightning was strong enough to light up the room in the fading light. You could tell the direction the light was coming from, first to the north, then south. Rumbles answered all the flashes. The computer chimed. EmergencyEmail.org reported rainfall rates of two inches an hour in Pinellas. Urban flood advisories were issued.

The storm has passed now. We didn't get the torrential downpour I thought we would. The thunder has quieted, the lightning dimmed. There is still a lot of rain out there. In an hour or so, the storm will have moved offshore. Lightning may still dance across the sky, but the thunder will be too far away to hear. Outside, the side walk is still wet... proof that a storm had passed by.

DragonCon: Out of Context...

"If it weren't for my horse, I wouldn't have spent that year in college..." Lewis Black

On of my favorite Lewis Black routines describes over hearing a conversation at his local health club, The International House of Pancakes. He describes hearing a part of a conversation that, because it was so far out of context that it seemed farcical, but was also great fodder for a comedy routine. He must have spent 15 minutes debating the meaning of that simple partial sentence... Very funny...

Last year at DragonCon, I caught a number of partial conversations, which when taken out of context, were not only strange, but very amusing. Now, I know you shouldn't listen in on other peoples conversations, but some times people just make it so darn hard not to overhear what their saying... So in honor of a tradition inspired by Lewis Black, I bring you this year's "DragonCon: Out of Context"

"This is my nightmare, this is my nightmare, this is my nightmare..." 8 year old boy writhing on the floor of the Sears store in St Pete while waiting for his mother in the checkout line (we were buying jeans to take with us to Atlanta.)

"Maybe the nipple clamps wouldn't come off." A fellow DCon'er recalling a loud event outside their door at last year's DCon.

"I love jumping out of airplanes, but I hate flying..." - a paratrooper on the plane on the way to Atlanta...

"Religion is the reason we have short, fat people today... and civilization."

"PeachTree Center. It's like the Mall between the convention centers."

"Boobs or Booze?"

"Could you look in my desk drawer, find my checkbook... and pay my rent? Don't worry about the signature, they don't check it... unless I contest it. So how was work?" - Um... the Con started on Sept 4th, how could you forget to pay your rent on the 1st?

"OK, seriously, if last night keeps happening, I'm going to have to buy a second kilt." - Twitterer @ DCon

"Everything's better with Pandas."

"There are Jello Dynamics moving down there..." Watching the crowd in the Marriott Atrium from the 4th floor.

"Spikes? I got Spikes. Move or get Perforated. I love herding people."

"The product costs money. The abuse is free."

"My backpack is heavier then I am."

"Four words: Naked Pregnant Space Kitty." - same Twitterer

"What I really want is teleportation. I don't want to have to walk" (DCon is spread across 4 hotels covering 6 city blocks end to end...)

"Female Peacock..."

"Unfortunately, the genre of cyberpunk, paranormal, romance is almost dead." It was ever alive?!?

"He's a 6th level lawyer with a +1 in technology" - about the GA lawyer in the digital forensics panel.

"My car breaks down... I blame Vista..."

"If you want to take him to the bathroom where you can barely stand, you can change him."

"I think he slept in that mask"

"I don't know... my coffee stopped working." - in the Chili's in the Atlanta airport.


For those of you I quoted... thank you... I promise to keep you anonymous...

Twenty Years.

As I was walking down the stairs to go to the All Hands Meeting this morning, Jack looks up at me from the lobby and says "There's Karen." Sandy says, "I thought she was here today." Uh Oh. That usually means your going to get called out for something at the meeting. Either you've know something they want you to tell everyone about (a project or other event). Or you've done something.

Me? I'd done something...

Hilary had walked in with me... Do you know what's up? Yeah, I had an idea.

Jack started the meeting with it. I was standing on the side with a cup of tea in my hand. "Karreennn" he says, picking up a folder with something small stapled to the front. I put down, my tea, and took one step forward. I paused, "Whhaatt?" It got a good chuckle from everyone. Then I walked up to the front, trying not to blush. Jack looked at me... "Do you know what this is about?" "Yeah, How long I've been here, right?" "Is it two years late?", he said, as these things are usually awarded several years after the fact. No. Keith pipes up "Two years early?" Everyone got a kick out of that, too. It would have been a classic Government move. "Karen has been with the Survey(?) 20 years." Jack continued. "Almost 19" I said, "But yes, just passed 20 years Federal Service." There was a certificate embossed with a seal very similar to the Presidential seal, in silver, with a 20 at the bottom. We are part of the executive branch after all. And a lapel pin. A USGS buffalo with a little banner at the bottom that said '20 years'. In truth, the government always takes about 2 years or more to process these things. Jim got his 10 year pin earlier this year, after being here about 15 years... maybe more. I wasn't expecting to be called out so soon.

It's hard to believe that I've been in this office for 19 years (next month). It's equally as hard to believe I've worked for the government for 20 years, starting with the DOD in Maryland. It really doesn't seem like all that long ago. I'll hang the certificate in my office next to the certificate for 10 years of Federal Service. Have I said I love my job? I do. It's something I consider worth doing, because I serve my country. It's something I'm proud of, and it's something I will, in all probability, do for another 20 years...

Dryer Vent Follies...

Our dryer vent exits on the roof. It goes straight up from the floor of the laundry room, through the attic, to the roof. I guess they thought that was shortest route. Probably the easiest to install, but far from easy when it's comes time to clean it. And we try to do that once a year, or when cloths start to dry more slowly as the case has been in the last few weeks.

To do this, one of us has to get up on the roof. That's usually me. My hands are smaller and can get under and into the vent, which is curved to keep the rain out. The top wasn't that clogged this time, which is good. A few months after the roof was replaced the dryer started taking forever to dry cloths. It seemed odd since while they had the roof off and the dryer pipe open we cleaned the heck out of it. The vent hood was also being replaced and it was the one and only time we had a straight shot down it to clean it. When I got up on the new roof that day, I found that there was a screen on the hood, and that was completely clogged. This after we'd called out service to look at the dryer. "Your vent's clogged... We don't do vents... $40 bucks, pleased". We removed the screen... permanently. Sigh.

I climbed up on the roof that morning. Not the best time to be doing this. It had raining, which meant the roof was still damp, because the sun hadn't risen beyond the trees. It was, to quote one of Edward's more colorful phrases, "slicker then snail snot" up there. I didn't stand, but crawled the 8 feet to the vent. To clean it, besides sticking my hand up under the vent to pull out the caked on lint, we drop a chain tied to a rope down the pipe. This usually knocks off any clumps of lint stuck to the inside of the pipe. It also allows us to tie the vent dryer brush to the rope and pull it through the whole length of the pipe. You see, the pipe is about 15-18 feet long. The brush handle, before we snapped off the last foot was maybe 6 feet long. We tried just using the brush but ended up clogging the pipe about 6 feet up, where the brush pushed all the lint to.

The chain was being difficult that morning. It didn't want to feed into the vent and fall. Once that was done, I fed Edward the rest of the rope. Unfortunately, I was supposed to hang onto one end so that we could tie on the brush and pull it down the pipe. So I had to feed it in again. Then once the brush was tied on it didn't want to feed in to the hood. It is a tight corner. In the process of doing that the handle of the brush first pinched, then caught and stuck the skin on my left arm. Son of a b***... It took a second to free it. It's kind of like slamming your thumb in the car door. First there is the Son of a b*** moment, then the tug... sh** I'm caught moment, then the trying to get yourself free moment, follow (optionally) by the colorful language moment. It left a bruise about the size of silver dollar and a welt about twice as thick on my arm. In a few days, it should be a lovely shade of purple, turning to that even lovelier shade of "jungle rot green" healing bruises always acquire.

At least the vent is clean and the dryer is working. Sometimes we have to fiddle with the hose to get kinks out of it after we're all done. But it seems to be fine at the moment.

And as a bonus... I didn't even fall off the roof...

Mara. Up Close.

Lying in the sun...

Upside down...

Paws at the ready...

Nose in the sun.