Water Table

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

WCA3A Update
Deepest pool is shallower than normal

Hydrograph of WCA3A in the Everglades
Hydrograph showing current water depth (blue) relative to the elevation of major habitats of the ridge and slough ecosystem, the statistical record from 1993 to present and the new regulation schedule (COP)
Calendar chart of water depth in WCA3A of the Everglades
Calendar chart of water depths in WCA3A using the same color scheme as the hydrograph above

At first glance, the water table looks simple.

You can touch it with your finger and sure enough it’s wet.

The difficulty lies in understanding where it’s at relative to the suite of hydro-ecological and statistical metrics we measure it by. Case in point is Water Conservation Area 3A in the Everglades. Statistically, it’s a foot below where it normally is for late August and three feet below its high-water crest following Eta. Ecologically, water depth in the sloughs are about 1.75 feet deep but the tree islands are still dry.

That’s relatively rare for WCA3A this late in the summer.

Full story …
Or partial keyhole view?

The calendar chart (top) is color coordinated with the diagram (bottom)

The beauty of this chart is it allows us to see the full water history of Big Cypress National Preserve. The caveat is that it’s only a single gage. And this may even be a bigger one: It doesn’t tell us how water changed in the run up to the preserve being formed, and especially after the Tamiami Trail in the 1930. The trail not only paved the way for connecting the two coasts, it also became the de facto backbone for draining the swamp. Fifty years later the Preserve was established, and that’s when our hydrologic record keeping begins, too.

The biggest trend in my eye from the graph above is the longer summer wet seasons. That’s not because we’re getting more rain, but because we’re doing a better job of spreading the water out. The biggest shift for the Preserve occurred in the early 1990s after Alligator Alley and Turner River Road were replumbed to divert less water. This summer’s taken a little longer to start up, in part thanks to a deeper than usual spring drought. But the bigger trend is that it’s wetter now than when the Preserve was established (in 1974) but not as wet as before the Tamiami Trail went in.

So it’s a partial story, but pretty interesting (and revealing).

Data is good.