Recent floods in Duluth, Vermont, Oregon, New Jersey, and elsewhere came with indications of more to come. So here’s a look at one aspect of what it takes to guard against and cope with flood danger. This is a third installment in a series of articles on our nation's infrastructure and its imperiled condition, trying to bring engineering issues into laymen's terms.
This is a third essay in a series on America’s infrastructure, energy challenges, and related issues, from an engineering perspective, put in laymen’s terms as best I can. I am an electrical engineer, not a civil engineer, and DailyKos’s CivE contingent may need to lay the occasional smackdown if I get something wrong. So I’ll start with this disclaimer: conditions in your community may vary. Other issues may overshadow what I’m writing about below. It never hurts to talk to the proper pro.
I am a few days late on this article, and was moved to get this done by the return of Jerome A Paris to DK, and by a sad news story I’ll relate below. So shout outs Jerome, and also to all the people who make their flickr uploads available for use under a Creative Commons license. It’s so nice to find pictures of all the things I want to kick myself for walking past and not photographing.
1. A primer on the smart grid for laymen.
2. In laymen's terms: the 100 year flood.
High water markers in Bachrach, Germany
The Inter-Testamental Period in Jewish history featured a colorful mystic named Rabbi Honi the Circle Maker, whose life can serve as a good intro for almost any essay. One reason is the time he brought rain. Legend has it that one year when the rainy season was late to start, the people asked Honi for help. And so he drew a circle in the dirt and informed God that he would not leave the circle until the rain started. For several days, nothing happened, and Honi kept Occupying the circle. Then it started to drizzle weakly.
Honi informed God that he did not ask for a mere drizzle, but wanted a rain that would fill the cisterns of Israel’s villages. It promptly began raining furiously. and Jerusalem was flooding. So Honi raised his voice to God and said he wanted rain that would be a blessing to the people. And the rain slowed to a gentle farmer’s rain.
For reasons detailed in other stories, Honi was sufficiently Awesome(TM) for the Lord to smile on his antics. As another rabbi said of him,: But what can I do to you, for you act like a spoiled child before God and nevertheless God accedes to your requests. For example, the child says ‘wash me in hot water,’ ‘rinse me in cold water,’ ‘give me hazelnuts, almonds, peaches, and pomegranates,’ and the parent grants each of these requests? It is to you that the verse refers: ‘Your father and your mother shall be glad, and she who bore you shall rejoice.’ ”
We need Honi. Would that we could have someone with that Divine privilege interceding for us today. You might wonder what is worse: a drought, shriveling your fields and gardens, drying the soil so the wind can take it, impoverishing your community, or a deluge coming down by the foot. Well, if you live in Texas, you can have both! Not enough rain falls most of the time, and then it comes in torrents that wash away what you have and leave you as dry as you were before.
And here is why: water is heavy, and it gets momentum. Picture a water tight cubical box, 40 inches by 40 by 40. Now picture it filling with water. The net weight will be over one ton. Metric or Imperial. People have a hard time getting an intuitive sense of the density of water, and its implications. One of the more shocking pictures from the Duluth floods is viewable from this page. See picture number 4. Notice the vertical pipe connecting the manhole to where the road used to be? It naturally led to a drain pipe below. When a sufficiently fast flood comes to your storm drain, it backs up. Because the water is heavy, the backup applies a strong pressure against the bottom of the pipe. If there's a small leak, the water will shoot out at high pressure. And scour the soil nearby. Hence that nasty sinkhole. Water is heavy. It is also thin. (Versus oils, which are light and thick.) And this combination means water can pick up serious momentum as it flows downhill.
That momentum can mess you up. Fast flowing water, even just a few inches, can sweep you away and kill you. And it can beat the living hell out of everything you build and rely on. Also, once water gets going, it gets turbulent, picking things up. Among these is the dirt, which it forms into a suspension that is even denser, and can mess you up even worse. And finally, water in motion tends to stay in motion. To keep going, out of your reach, to where it won’t do you any good. So momentum is the enemy. The way to manage the rain is to retard its flow. Impede its flow. Sometimes to just stop its flow. And while the water is lingering thanks to your efforts, the thing to do is to help as much of it as possible seep into the groundwater, where you can use at your leisure, or where you can, um, save it for a rainy day. Notice how areas under a tree canopy stay dry well into the onset of a rainstorm? So do all the people in your town's public works department.
Just as vegetation retards the water, removing it does the opposite. Say I have a house and a yard, which are just uphill of a neighbor. My land drains directly on to his. When we each get an inch of rain, my grass drinks up some of it, and some goes into the aquifer. The rest flows through my lawn on to his. But by the time it reaches his yard, the inch he got has itself been drunk up and drained out. So his yard stays wet longer, saving him time on lawn care. He’s happy. Now I decide I hate mowing my lawn and I pave it. Again we get an inch of rain. And my inch of rain immediately flows over to his yard, not even impeded by the texture of grass. 5 minutes later my wasteland is dry. And his yard has two inches of rain to deal with. Now picture what happens in a real storm. I might be fine. But my neighbor is distinctly unhappy. Now picture what happens when uphill areas are developed and paved, and drain much faster onto a river. This is what has been exacerbating flood danger all over the country.
This is what happened in New Jersey. Basically, every last acre of land that could plausibly be given to suburban development, has been. Now downhill towns in New Jersey see the storm waters come to them faster than ever before. Just like no spammer accepts blame for your email box being unusable, no raindrop accepts blame for the flood, and no driver accepts blame for the smog, no New Jersey homeowner is going to accept blame for what happened along the coasts and the rivers. But every square inch adds up. If you live in an area with flooding issues, you have to look at your options. And that means looking at what others do.
Suburban arterial road. Pave enough of these and you start to have problems.
Somerville, Massachusetts is one of the most densely populated cities in America. There is not much on street parking, and so over the decades, most homeowners paved themselves a driveway where they once had a small garden. Over here we too have seen storms get more intense, and nowadays it’s common for flooding to hit low lying areas in the city. Meanwhile, Somerville has become a popular city for alumni and dropouts of the local colleges to settle in (and the rental scene in the city is Boston’s answer to Avenue Q), and so more homeowners are starting to remove their driveways in favor of gardens, and in favor of hoping the city’s storm expenses (and their taxes) will decline. In the summer, there are occasional parties where people are invited to swing pickaxes into the concrete to get the process started.
Now it takes the eccentric residents of Somerville (culturally annexed into the People’s Republic of Cambridge) to start on something as seemingly un-American as de-paving. We take it on faith that every business area should have enough parking for peak business days. Our shopping malls have parking for Black Friday, which sits 90% unused the rest of the year. And of course, we pave big wide roads everywhere. There are some surprising reasons why. When the founding colonists came over, they had to build homes quickly, and so they built with wood. And America never did gain a big tradition of homes made with stone masonry. So they had to worry a lot more about fire. So they spaced homes further apart, developing a preference for wider streets. With wider streets came the ability to make U-turns with a horse and carriage, and ZOMG, newcomers from Europe thought that was the Best. Thing. Ever. So we got used to wide streets. And wide roads. And lots of parking. And so before we knew it, we paved our way to serious trouble.
Yes, roads add up. Take a suburban arterial road. Two traffic lanes each way, one parking lane each way, and one turning lane. 7 lanes. At 12 feet per lane, that’s 84 feet. A football field is 360 feet by 160. Which means for every mile of arterial road, you pave 7 football fields. This stuff adds up to a big problem in New Jersey. It also adds in large part to the reason parts of Texas get the joy of suffering droughts and floods at the same time. All that pavement drains to the Gulf Of Mexico, leaving nothing to save for later. But that certainly does not apply to Vermont or Oregon. They did not go crazy paving everything in sight. But they could still make do with less. Far less. Take a look at these pictures of the Austrian province of Tyrol.
Tyrol. Where the River Spirits await the day when they will finally receive permission to keeeel you.
Mayerhofen, Tyrol, Austria. Note the two lane main highway. The rest of town is mostly served with one-lane, two-way roads.
Tyrol is in the Alps, and they too have big problems with flash floods coming down the mountains. Notice the narrow roads. In the parts of Tyrol I visited, standard roads are two-way, but one lane. For oncoming traffic, you slow down to a crawl. You both edge over the side into the gravel shoulder, and proceed. The highway up each valley is two lanes. And the 4 lane roads through Tyrol? There’s one. It’s the autobahn to Germany. And surprisingly enough, they do just fine. Bacharach in Germany faces the lower Rhine near its narrowest point, so naturally it is also flood prone. Hence the photo I posted above. That region also keeps pavement to a minimum, albeit not as extremely. One should bear in mind, however, that these regions built their roads this way for reasons that are also accidental. Tyrol and the Mosel Valley were both part of the Roman Empire. Those Roman roads were built to last. Many remain usable to this day. And they were built for walking. Their width was that of the proverbial two horse hinds. They built this way out of habit too.
Climate models indicate that rainfall in the Midwest will become less frequent and more intense. So more drought and more deluge. And that is what fell on Duluth. In Vermont and the Berkshires, tropical storms weren’t much of a concern in the past. The storms are usually spent by the time they reach the Northeast, and the coastal regions absorb what energy they have left. Hurricane Irene shows that this is not the case any more. Now the residents of the narrow valleys of the Connecticut River are on notice that there may be more Irenes to come, and rain in their part of the country concentrates from hill to vale very quickly. In Oregon, what used to come in the form of snow is now coming primarily as rain, and so it reaches the valleys a lot faster. And New Jersey actually did pave her way to trouble. The Atlanta area now has a drought, a severe one, in large part because of all the water the suburbs of Atlanta run off right into the rivers. When the drought breaks, we know exactly what will happen. But all of these regions have options for dealing with that problem, and removing pavement is a highly effective one.