Pools are for swimming

We have a swimming pool at our house.

It’s a big pool by Florida standards – it measures 32 ft long by 17 ft wide.

That makes it “great” for swimming laps, but only “okay” for equating Everglades flow volumes.

Let me explain.

The standard “scientific” units for measuring stream flow are cubic feet per second (cfs), but if you read the “newspaper” chances are you’ll see stream flow expressed in the units of Olympic-size swimming pools … or rather, how long it would take to fill one up.

The Olympic-size pool dwarfs mine – it measures 164 ft long by 82 ft wide and holds 660,000 gallons.

But since I am a hydrologist, and not an Olympian: my standard unit of water is the pool in my back yard. It holds 15,000 gallons, or around 2,000 cubic feet.

A flow rate of 1 cfs would fill my pool up in 33 minutes.

(And that would be a pretty big hose by the way – more comparable to a direct tap from the fire hydrant than the standard trickle from a homeowner’s spigot.)

If we kept the hose running for a full hour it would discharge 3,600 cubic feet of water:

Spreading that volume evenly across a football field (which is an acre in size) gives you a field of water 1 inch deep.

An inch of water per hour is a very familiar number in south Florida, or at least per day!

Rain routinely falls at that rate during any number of our afternoon thunder showers.

To bring this full circle:

Consider the case of the Kissimmee flowing into Lake Okeechobee at a rate of around 3,000 cfs … or 3,000 times the volume of our imaginary hydrant-tapped hose we used to fill my pool.

While I’m not sure how many swimming pools that fills up,

I do know it will fill a giant empty glass (with a 2 acre base) to the height of the Empire State Building twice per day.

In summary,

Pools are great for swimming laps and for cooling off in the Florida heat … but they make lousy hydrologic measuring cups.

I recommend tall buildings or football fields instead.

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