Friday, June 20, 2008


For a few years in the Nineties I was the “flood plain lady” for the City of Portland. That is, I was the clerical specialist for the Site Development team, who had custody of the flood plain maps, and when someone called up to find out whether a property were in the flood plain, I was the one who was supposed to tell them. The maps were huge and there were a lot of them. I’d unroll them on the counter and try to figure them out. They were out of date. The flood plain was a legal category built on engineering estimates of a changing terrain and weather pattern. The public never understood that: to them it was simply whether the place would flood. Would it flood every fifty years? Every hundred years? Every five hundred years?

Hell, who cared? They just wanted to build what they wanted to build and they saw all this land sitting there with nothing built on it. Seemed perfect. Nice and cool. Fairly flat. Good view of the river... They asked their neighbor who had lived there ten-twenty years and the neighbor said it had never flooded before.

There is so much pressure from the public that the politicoes force the plans examiners to let people built on the flood plain if they build “flood resistant” buildings. (There’s no such thing as a flood-proof building.) Mostly they required high foundations, so the sills of the house were above the height the water was likely to reach. Foundations with holes in them, so that water would flow through. (Waterborne gas tanks, sheds, vehicles and trailer homes would NOT flow through.) If water comes up one-third of the way on a structure, it will float -- then turn over -- unless it’s attached to the foundation with steel straps.

One woman formerly from the Soviet Union came back with new plans every week. The last one showed foundations thirty feet high with a little one-story house perched on top. She knew from her experience in the homeland that if she nagged long enough, the authorities would shrug and say: “Aw, let her build. If she loses everything in the next flood, she asked for it.” But we held fast. She had no clout.

The point of quantifying flood damage and likelihood was actuarial because the US insures people devastated in floods. I remember as a small child watching the newsreel footage of houses floating with people in the roof, sometimes clutching their dog. The whole Missouri/Mississippi complex evolved as drainage for the North American continent on the east side of the Rockies when the glaciers finally melted ten thousands years ago. In the Thirties the engineers thought they had tamed the rivers, and they had certainly spent a lot of money.

When engineers go after a problem, they try to quantify and calibrate and invent classifications for sorting. So they got out all the rainfall measurements (since the 1800’s when there were white people around to keep records) and then they figured out how much water that must have been rolling down the rivers. Then they got out their contour maps -- the ones with all the little lines that show elevation by getting closer and closer together as the rise gets steeper -- and tried to calculate the carrying capacity of the flood plains. They chose one of those elevation lines to be the isobath, the height they figured the water would reach. Of course, those lines greatly simplified the terrain and they were drawn quite a while ago. Land doesn’t just sit there: people fill in with more dirt, banks erode.

The Flood of the Century in the Red River country in 1997 -- which was a few feet deep and miles wide -- was complicated because the Red River flows towards the north, so it melts from the south while the water is still frozen farther north, creating dams that raise the water level. The floods came so often in Winnipeg that people finally consented to create diversion canals -- they were barely adequate. Grand Forks failed to take any precautions so that the water came deep and hard. When a fire started, no one could get to it so it took out eleven buildings and sixty apartment units.

The flood about the same time in the city of Portland had nothing to do with ice: it was about heavy simultaneous rain in BOTH the drainage of the Columbia and the drainage of the Willamette so that they met at the city. Such a chance event, unpredictable as are many things when it comes to weather, was so unusual that the people -- many of whom moved there because the city was “pretty” and “civilized” -- had insisted that the top of the downtown flood wall be removed so they could see the nice view. (Historically, Portland has always been vulnerable to floods.) Luckily, there was a lot of new home construction and when the mayor put out a call for help, crews came from all over town with plywood, plastic sheeting and their hammers to save the downtown. It barely worked.

The levees that were supposed to be saving the airport from a repeat of the Vanport Flood had been breached by muskrats and nutria, burrowing in and out, and were bubbling up water from the ground on the “safe” side of the levees. At the airport the big planes that couldn’t be flown out quickly were towed up to a highway -- quite a sight. Shopping malls and manufacturing businesses had built where Vanport used to be. The mayor had to decide whether to evacuate them or not. She decided not, on grounds that lives might be lost through the chaos of evacuation and the city would be liable. Of course, if Hayden Island had flooded again, lives would also likely be lost. Luckily, she won her gamble, but it could have gone the other way.

Not long afterwards someone suggested that a much-needed county jail be situated on that flood plain. The head of Site Development, a quiet but stubbornly intelligent man, went to a hearing to tell them how likely it was that the jail would be flooded and that rising water might lock all the fancy electronic doors so that no one could escape. Another person at the hearing sneered, “Who cares? Good riddance!” Our hero, our boss, pointed out that his own brother was a guard at the jail and did not by any measure deserve to die. If anyone does.

It’s hard to educate people who don’t want to know. It’s hard to commit massive and expensive relief efforts to people who have been warned and warned and restricted and guided over and over and over again. But we are being taught hard lessons in the wettest of ways. The bottom line is that the earth does not care. Romanticize all you want. Floods, hurricanes, earthquakes, erosion, rainfall patterns -- no engineer can do much more than run along behind taking notes.

But people got so angry that when I was the flood plain lady, I kept a can of bear spray under the counter. If I’d had to use it, of course, the building would have had to be evacuated.


Anonymous said...

Very good commentary on the folly of building on floodplains. Here's a counter-intuitive story:

Before settlement, the valley of the South Platte River in Colorado was heavily grazed by buffalo, which gnawed grass down to the roots and destroyed the riparian areas. This overgrazing caused violent and terrible flooding now and then when water tumbled out the Rockies.

When the buffalo were killed off and ranchers fenced the bottoms, the riparian areas began to regenerate and today are lush riverside bottomlands with huge trees, brush, abundant game, and porous soils that blot up flooding. The violent floods have ceased largely because the ecologically healthy bottomlands now blot up and subdue the floods. the last disastrous flood was, I believe, in 1935. The river flow itself has evened out.

Usually mankind is the destroyer of nature, but in this case the hand of man generated a healthy ecosystem.

Richard Wheeler

Peter said...

If it weren't for federal flood insurance there'd be much less building on unsafe flood plains.

Art Durkee said...

Here I am in the midst of the current floods in southern Wisconsin. I went to the downtown yesterday and got photos of things rare to see, and a little frightening: how fast the Rock River is moving, how far over its banks it's spilled.

How wise it is to build on the rise of land OPPOSITE the floodplain, and not on the plain itself.

It's hard to save people from their own idiocies. One might wish to do the good thing, but it is indeed wearing to have to fight uphill against their stubborn insistence on having their own way, right or wrong.

My feeling is: Okay, fine, build there if you really want to, and won't listen to the engineers. But if you do, you abdicate your right later on to sue anybody about it, when it all goes wrong.

Maybe that should be put into document form that they'd have to sign. I wonder if it would deter them.

prairie mary said...

As the joke goes, "denial" ain't just a river. (You have to say it out loud.) The obvious solutions (like cancelling flood plain insurance) don't fly.

Prairie Mary