Living on a flood plain
I possess a somewhat morbid fascination with catastrophes and flooding certainly counts as one. A Force of Nature. An Act of God.
I have been following the recent flooding in the Midwest.
I also tracked floods in areas I used to be familiar with such as
Big Thompson flood of 1976. When I was growing up, my parents and I used to vacation in this very area up until when I graduated from High School in 1969.
So when I check in at
Prarie Mary, it was interesting to read
her most recent post:
THE FLOOD PLAIN LADY SIGHS
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 They were out of date.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.
A bit more:
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.
She closes with this:
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.
I am on a County-localized email list and someone there asked how to build a garage without having to get a permit because the architects and engineers fees were so expensive. Same damn mindset. See it all the time.
The bear spray doesn't sound like a bad idea actually...
Posted by DaveH at June 21, 2008 10:14 PM