Lessons from the Nashville flood

Last Monday, Nashville, TN, saw the worst floods in 75 years.  As the rain pelted down Sunday night, I was a hundred miles to the east camped out in the Smokey Mountains, listening to the thunder shake my trailer like the inside of a drum.

The next morning as I left the park, I passed the Little River, where two forks come together just above Townsend, TN.  The river was raging.  Where I had sat by its shore the day before reading the paper, dark waters were racing by.

It poured all night.  The Little River in TN, just above Townsend.

A day earlier, I sat here reading a paper beside the river.

Later, as I crossed the Tennessee and then the Ohio Rivers, I could see jams of debris--logs floating in the muddy waters.

There's a pungent essay about the floods in Nashville here.

All this set me to reflecting about floods... and stormwater.

In the Great Smoky Mountains, the watershed is in perfect health. 

A few days before the big flood, I was walking in a moderate rain that had been continuing for several hours.  Although I was getting soaked, the land was sucking it up like a sponge.  The water wasn't accumulating in pools anywhere--and it wasn't running in little streams across the ground anywhere.  The streams didn't swell during the rain, and the next morning, they didn't seem any more full than before.

So during normal storms, a healthy watershed soaks up all the rain.  But as I saw, there are extraordinary storms--or there are times when the soil is already saturated from previous storms.  This is when floods occur--and they are natural, even in healthy watersheds.   That's what floodplains and wetlands are for--to absorb and delay stormwaters the land can't absorb.

These natural floods do cause some erosion, especially along streambanks.  The resulting cuts in the bank create places for bank swallows and kingfishers to nest.   Again, the eroded soil is trapped in the wetlands downstream, where it does little harm.  Soon the waters are clear again.

What I learned in the Smokies

It's a mistake to think our city infrastructure--our storm sewers and channels--can handle all the floods.  There's a point beyond which it isn't productive to prevent flooding that occurs once the soil is saturated.  It's too expensive.  We need to find ways to live with the occasional flooding.

By living with flooding, I don't mean we should ignore problems caused by too much pavement.  Clearly, we need far more programs to deal with rainwater where it falls.  Madison is very backward in this respect.  Large buildings need green roofs of succulent plants.  We need rain gardens on the terraces and other areas nearby to handle street runoff--for every street except downtown areas.

And we can't stop all the erosion.  For example, on the west side of Pheasant Branch Conservancy, an eroding gully was filled with enough stone rubble to choke the Grand Canyon (photo).  The erosion needed to be stopped, but the solution was complete overkill.   Likewise, I think the solution to erosion in the Hillcrest-Upland Greenway is overdone.

A balanced approach

What I am talking about is the right balance.   Soak up the light rains as completely as possible where they fall--but when that fails in extreme storms, learn to moderate and live with the resulting floodwaters.

By live with flooding, I don't mean stand by while people drown.  I mean alternative, softer, less destructive solutions.  If some businesses along University Ave. get flooded too often, relocate them.  If saturated soil in an area causes a few flooded basements, the city needs a program to help citizens waterproof their basements.  Lacking balance, the city is too focused on building bigger and better ways to speed floodwaters to the lakes. 

We have a knee-jerk response by City Engineering to complaints.  If there's a problem like flooding basements or a stream wandering too close to some one's house, people scream "fix it!"  And the city applies a Band-Aid to the problem.  

But there's no voice, and no process, to ensure that the watershed is improved over the long term, so floodwaters are moderated at the source, where the rain hits the ground.

If only someone could complain: "There's no rain garden here!"  And the city would fix it.  Don't hold your breath.  That this sounds so laughable shows how far out of balance we are.

Madison is too focused on stopping floods downstream from where the water falls.  We need to relax that approach, learn other ways to moderate damage from inevitable floods, and refocus on stopping runoff where the raindrops hit the ground. 

That would be a better balance.

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Click here for a slideshow of flooding on the Little River.

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