Sheet flow swamp

How often (and when) …

Does peak sheet flow occur in the swamp?

Sheet Flow Calendar, 1968 to present

Answer: Not usually in December, but sometimes.

A situation similar to this year occurred in 1994, and to a slightly lesser extent in 1999, 2005 and 2017.

Our highest chance for peak sheet flow …

are the months of September and October.

Typical sheet flow distribution, by month

Of course the amount and duration of flow varies from year to year.

Sheet flow gets stifled

The concept on sheet flow …

Is that water spreads out evenly everywhere.

OK Slough is slumping
well below its normal wet
season level

But the rise of the water is variable, too.

Cowbell Strand is in full summer saturation mode.

Meanwhile, OK Slough is just now barely getting wet.

As for the reason? 

Blame some combination of the residual effect from the deep spring drought, lack of recent rains in that area, and the nearby canal that is whisking water away at a healthy rate.

Solutions, big and small

Now that the wet season has begun,

It’s a good time to take hard look at the bridges where water flows …

Every bridge deserves its fair
share of summer flows

Or doesn’t flow enough.

Often vegetation gets blamed for clogging them up.

Bridges need to be maintained structurally …

And hydrologically, too.

Sometimes little tweaks can make all the difference, as shown above.

Single source swamp?

Are springs the source of the swamp?

Answer: No.

Sheetflow swings high and low,
whereas springs gush steady all year long.

The swamp gets all its water direct from the sky. As shown on the hydrograph above, that means a feast and famine diet. Or in other words, lots of water all at once in the summer and then slowly receding and disappearing water through the winter and spring.

As for the springs, they aren’t fountains from nowhere … although they seem that way when you see them. Almost like a water fountain left in the “on” position, springs flow non-stop and quite constant all year long.

The Floridan Aquifer is their source.

From left to right: sheetflow, spring flow and Lake O flow (at Moore Haven S-77)

Was Lake Okeechobee ever the source of the swamp?

Answer: Yes, or partly, or at least to some degree … from the Ft. Thompson Falls pooled Caloosahatchee which fed seeps that that drained south into cypress strands and marshy sloughs. Today, the S-77 controls water leaving the Lake in that direction — which hasn’t been open all summer — and the Ft. Thompson Falls are gone.

That’s why each night when the clouds aren’t there the swamp thanks its lucky stars that you can’t close the control gates to the sky.