Pine high ground

High and dry in the pines
September is (usually) peak season in the swamp

You know we’ve finally hit the heart of the wet season …

When the pinelands are shallowly flooded.

Bar chart showing hydroperiod (i.e. duration of flooding) in the pines of Big Cypress National Preserve over the past 30 years.

Over the course of an average year, we can usually count on the hydric pines going under for a good 4 months of the summer/fall period and the higher-perched mesic pines getting inundated for about a month.

And usually September is reliably our peak water season.

Except this year.

The water table is inching up but still below the pine trunks.

Hydric pines during wetter times

That makes this year drier (i.e. less wet) than the drought summer of 2000

Shallow sea reaches peak

Well, it took all summer,

And the end of the rainy season is just a week or two away …

Water should start to slowly
drop from here, or will we have
an October bump?


B
ut water has finally risen …

Into the pinelands.

And is splashing at the shores of the mesic hammocks.

That’s not Irma deep, but it’s as deep as it’s been all summer …

And probably at its peak for the year.

Swamp cycle revealed!

The continental water year typically starts anew in October.

In peninsular south Florida, May marks our water year start.

Animated map depicting the seasonal ebb and flow of flood and drought in Big Cypress National Preserve

Why the difference?

Water years are typically aligned to start at or around when waters bottom out.


Up north that happens at the end of the hot summer, i.e. fall.

For south Florida it happens at the end of spring.

South Florida is currently 5 months into its water year.

Wet (versus rainy) season

Poor drainage is a strength of the swamp,

That’s what helps keep it wet even when the rains shut off.

This graph provides a comparison of south Florida’s rainy and wet seasons, as defined by me. I‘ve always preferred the use of rainy, not wet, to describe Florida’s summer period.

How long will the swamp remain wet into the winter dry season?

Answer: Each season varies, but usually the domes (not affected by canals) hold water through February, even into March.  Not only is that attenuation of water a result of the swamp holding on to its summer rain, but also an artifact of slower rates of evapotranspiration (ET) in the core winter months (December through February.) The swamp becomes weak when it is over drained, most usually by water-blocking levees and diversionary canals.   

In summary: Despite the start of the dry season wetness of the rainy season lingers on.