Really, Most Major Cities Are Flood-Prone

[MineralMan]

Most cities are built on low-lying land near water. They were founded in those places because transport was mostly done by water. Oceans, rivers and other water features are near almost almost all of our largest cities. Then, we pave over the land and build everywhere we can in most cities. That means that rainwater can't be absorbed into the soil and must be dealt with in other ways.

That's true even in desert areas. Las Vegas, for example, floods regularly, especially on the Strip, despite being built in an arid desert. We like to build in valleys, near harbors, around lakes and rivers, etc. Transportation is the primary reason cities began near those places. Wherever there is water, there is swampy lowland that can be filled and built on. And so it goes just about everywhere.

I live in St. Paul, MN. The Mississippi River runs through the city. There are lakes and streams everywhere. Our city, like most cities, was built on the river, because that's how stuff got to it back before the railroads. We've had floods here, and the low-lying areas near the river are heavily built-up. Other parts of the city are on higher ground, but that just means that the water that collects during storms still has to be collected and directed toward the river. Everything runs toward the center of the city, which is right on the river.

If you look at most major cities, you'll see the wealthy part of town located on high ground and the less affluent areas in the low areas. Water is the reason, in almost all cases. Cities flood.

[Phoenix61]

1. There is a model out there somewhere that shows what

would happen to Manhattan if a hurricane ever hit it. Not pretty at all.

[MineralMan]

2. Yup. Sandy was just an example.

Worse, rising sea levels will make the problems even worse. I think we're also seeing storms that bring more water than before into many areas. Harvey has already been called a 500-year storm for the entire Greater Houston Area. When 40" and more of rain are part of a storm, almost no city can withstand that without serious flooding.

Climate change is having its effect, I believe, and there's more to come. And worse to come, I think.

With so many of our major population centers built oceanside, we're going to see an increasing level of threat from storms and flooding, I'm certain. But even cities like Phoenix, which are built far from the ocean, experience flooding when excessive rain falls. Many of them, too, are build on lowland valley areas which are prone to flooding.

When my wife and I moved to St. Paul, we chose a home in a neighborhood that is on high ground. It's even called Hayden Heights, because of its high ground. I think about stuff like that before deciding where to live. Our home is almost at the highest point, even in that neighborhood.

[Phoenix61]

9. I can see the bayou from my house

But I'm on high ground, for Florida that is.

[The Velveteen Ocelot]

3. This is true of many cities. We are more fortunate than Houston, though,

because it's not dead flat here; the whole city doesn't flood, and the water drains away a lot faster. We get heavy rains sometimes but we are not susceptible to the tropical weather conditions that create the sort of days-long deluge Houston is experiencing. In 1987 we got a thunderstorm that dumped about 10" of rain in only five hours. It caused a lot of flash-flooding; many roads were under water, cars were submerged, and a lot of basements flooded. Two people died. I was stuck downtown at work and was unable to drive home until about 1:00 a.m. (and that was tricky; fortunately I live on high ground). But the rain stopped by the next morning and the cities recovered before long. It was a mess but not anywhere near what Houston is experiencing.

St. Paul Downtown Airport has flooded several times (finally they built a levee around it). I have a lot of photographs I took from the air the last time it happened. All the airplanes had to be moved to another airport, except for that old DC-7 that's been there for like 40 years.

[MineralMan]

4. That's true in the Twin Cities.

Most of both cities are built on high ground above the river. Still, though, when we get lots of rain, there is localized flooding and, as you say, the Downtown Airport has flooded in the past, as have other low-lying areas along the river. Anywhere, too, flooded basements are a frequent issue. I've had some water in mine, when I forgot to keep the gutters clear and water came in through a basement window. I've corrected those problems, and installed a new sump pump in my basement last year, keeping the old one, which is still in good condition as a backup. I also have a generator that is dedicated to running the sump pump if a storm causes a power outage.

But both Minneapolis and St. Paul have good storm drainage systems, so we recover quickly after even heavy storms. However, if the amount of water carried by future storms increases, problems could get worse, I think. If we got 40" in three or four days, we'd have some seriously flooded neighborhoods in both cities, I guarantee.

[crazycatlady]

5. IIRC the only east coast major city not built on a waterway is Atlanta

(I think this was on How the states got their shapes)

[MineralMan]

6. There are some other inland cities that are not

built on waterways, too. They have a lower risk of flooding, in many cases, for sure.

Still, Atlanta has had its flood problems, viz:

http://www.weather.gov/ffc/atlanta_floods_anniv

[bearsfootball516]

7. Indeed

Chicago is pressed right up against Lake Michigan

[Wounded Bear]

8. There you go again, using facts and logic and rationality...

True story, and it's true world wide. Atlanta is, I believe a railroad city, built up and maintaind by the Iron Horse.

[kentuck]

10. Just about anyplace that gets 40" of rain will become a flood plain.

That's a helluva lot of rain!

[underpants]

11. Richmond flooded so often they put up a flood wall

Complete with locks and such.

Huntington WV and Roanoke VA are both in flood plains.