As the news comes out about the National Weather Service calling it a 500 year flood for the area around Cedar Rapids, Iowa, I think of another break point. That being what is known as Old River Control just north of Baton Rouge. It is also called, simply, "the structure".
The Mississippi River will eventually be captured by the Atchafalaya River, and the mighty Mississippi will cease to flow down to New Orleans and beyond. Instead, the flow will be diverted west.
Anyway, I suspect this record flood up north will stress "the structure", which controls the flow of the Mississippi at it's closest point to the Atchafalaya.
A fascinating book on this subject, and other attempts by humanity to thwart the inevitable, is John McPhee's "The Control Of Nature". I commend it to everyone as a great read.
We do have a habit of messing with mother nature at our own peril. Africanized bees would not exist without our interferance, fire ants another example. And the best planned efforts to control problems seem to result in worse problems. Louisianna had a problem with Nutria Rats by the millions. They brought in plants called water hyacinths that they wouldn't eat thinking it would slow the explosion of the little buggers taking over every water habitat in the state. They were not native to North America to begin with, they were brought in for the fur trade and a hurricane broke open their enclosure and the 8 rodents became millions. Then the plants took over the waterways and did far more damage than the little rodent ever dreamed of. Now in addition to the millions they have to spend anually trying to control the damage the rodents do to their levies and agriculture, they have spent tens of millions trying to control the vegetation that chokes off everything living where it flourishes.
Just like government, when we try to correct a problem that exists in the world, we more often than not, create bigger problems with our fix. It would be nice if we left well enough alone and let things take their natural and ever changing course.
Actually, calling it a 500 year flood is really just supposition since there are not enough records to prove it.
It would be more accurate to call them the odds of a certain sized flood. According to wikipedia, a 100 year flood is really a 1% flood and a 500 year flood is a 0.2% flood. These meaning the chance of it happening in any single year.
They base these 100 year and 500 year estimations on percentages. a 1% chance of such a flood happening in any given year becomes a 100 year flood. The problem is they don't always go in with the right expectations or historical data to make such broad predictions.
In the Texas hill country there is an area known as Flash Flood Alley. This area is one of the most flood prone and dangerous areas in the country to live. Seems they have 100 year floods about every 5 years. That's obviously an error in their system of prediction. The reason the error exists is, this is one of the most beautiful and desirable regions on the planet to live, when it's not underwater at least. Developers in that area aided by lawmakers and other powerful people keep the flood plain maps and laws pervting people from building in this high risk area from being prevented from builiding and re-building year after year, flood after flood. The new sub-division that gets wiped off the map creates an economic oppt'y for the developer to build another sub-division and the building industry, timber industry, local tax collector, hardware store and other all benefit from re-building and starting the process over. Many times at FEMA and your tax dollars expense. Not to mention the cost of lives by those moving into the area with no knowledge of the danger and past experience of those who lived and died on the property they're builing their beautiful new home on. It must be safe, my home is at an elevation above the flood plain! Doesn't seem to matter that it's also at an elevation that has been under the flow of a river countless times in the last 50 years. I'm certain there are other regions in the country with similar issues. If you live in Texas and expect the local news to cover or warn you of the problem and danger, you're out of luck until the next storm hits and the flood happens. Then they're all over it, talking about how this was the big one. "We never expected this type of devistation and loss of life. This is a 100 year event and very sad indeed." It's not a 100 year event, it happened 5 years ago! And again 5 years before that! Time to build anew and mend this battered community so life can go back to normal. At least until the next major thunderstorm hits.
In 2001 I was here in Houston when a little tropical storm came through named Allison. Not a hurricane and no predictions of disaster but it was at the time the costliest flood in US history. Twenty two deaths and over $5 billion in damage. Some areas here got over 26.5 inches of rain in two days and over 35.5 inches in 5 days. The record for recorded rainfall anywhere in the world is also in TX, a little town south of Houston named Alvin that in 1979 during Caludette got 43 inches in a single day. That one was confined to one community and the damage outside that isolated area was limited.
During Allison there were 18 wheeler rigs floating down the I-10 freeway and the water was flowing over the top of 23 foot high overpasses in the Heights area. After experiencing flooding on a massive scale and wittnessing the aftermath of Katrina on New Orleans where my brother lives, I have the utmost respect for the power of mother nature. My heart goes out to those affected by these floods.
Dang, glad I left Texas in 1992. Of course, I went through the flood in Ft. Collins. Thankfully, ours was not one of the houses under water. A lady I worked with had water from her basement to 3' above her floors in her first floor. She lost everything. Some others I worked with had 6-8 feet of water in their homes. It was fast, and in less than a week, all the flooding was gone. I saw on the news some tractor/trailers off of the interstate in water, I believe it was in Iowa. They're getting hammered up there and I too feel so sorry for them.