How can we better design cities to fight floods?

How can we better design cities to fight floods?

There are mild floods every now and then… Guess which area end up flooded? :D

We can't fight water, we have to adapt to it. Just upstream of the river (Nive) going right through the orange area, there are several kilometers of natural park. That is: of flood plain. Great for the migrating birds, also great to prevent worse floods.

 I would think massive storm surge is different than normal operation. Chicago is still underway on a massive drainage project that has cost $3 billion dollars, to build a huge tunnel deep under the city to drain water from Chicago out into a river far from the city. Learn to love water rather than trying to fight it. Good analysis. In Boise, where I live, and many other cities, new shopping centers, office parks and subdivisions must contain all the runoff water on-site. It’s common to see subdivisions built in the past 20 years to have a large park that’s sunken several feet below the street and shopping centers and streets have many landscaped depressions, some of them elongated, called swales.

The area of pavement and rooftops determines how much land must be set aside for runoff absorption.

As an added benefit, the oil and other pollutants carried with the stormwater don’t reach the river and instead percolate into the soil.

Amsterdam sits a couple of meters below sea level, but it hasn’t had a flood in 50 years even though it sits where a river meets a sea estuary. Its city plan shows why

Instead of building streets everywhere, Amsterdam has canals everywhere. When water threatens the city, either because the estuary rises or the river has rain downstream, there’s plenty of places for it to go.

Too many cities try to “channel” their water into a single convenient viaduct, including my home city Toronto.

This is the Don River in Toronto, This is the section that empties into Toronto Harbour. It used to enter directly into the lake over a marsh, but development on the marsh means it’s now diverted to take a sharp right hand turn about 400m south of that bridge you see there.

However, the Don is a massive river system. It drains almost a third of the City of Toronto and many storm sewers empty into it.

Moreover, in its early history, Toronto was crisscrossed with dozens of small creeks and rivers. Over the decades, they’ve been covered over or straightened out. They’re still there, but mostly underground or in concrete channels.

As such, heavy rains can be devastating as water rolls off Toronto’s paved streets on its way to the nearest storm sewer. During times like that, the Don looks like this.

Yes, that’s pretty much the same view as the picture above.

Now, in addition to providing natural channels, with lots of space to widen, keeping wetlands in place can also mitigate flooding. Swamps can absorb huge amounts of water in a flood, but instead developers fill them in and they become a flooded area waiting to happen.

In New Orleans, an area that is naturally low lying, they have long lived with a system of levies to hold back the water that virtually surrounds the city on all sides. Most of the time the levies work, but when they don’t entire low lying areas of the city can be flooded with over two meters of water. The channels that do exist are there only to help sea traffic and actually put more strain on the levies. It's happening at the moment, not far from where I live. Never ceases to amaze me. Only two months ago, when the river swelled during the monsoons, those flood plains were all inundated and boats sailed over the fields. But now the land owners have resumed “developing” the area. I've always wondered how the government sells such land and even allows construction activities on them. Anyone who plans on living/working there should keep a boat handy. 

Picture Source Google

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