Visions of a flow way

Pre-Cristobal makes name for itself in southwest Florida
Rain Or Shine Report for Aug 4th

Southwest Florida has been the rainiest of the southern peninsula’s basins since the start of June.

Thanks to an abundant three-days of rain from Cristobal a few weeks back, the Southwest Coast ended the month with 12 inches in July. That’s the highest July rain total for the Southwest Coasts since almost 15 inches fell in July 2001.
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Actually, it was pre-Cristobal … the storm wasn’t officially named until it passed into the Atlantic. But here in southwest Florida, Cristobal made a name for itself (as a rainmaker to be remembered) even before NOAA christened it with an official name.

Of course all eyes are on The Lake, and as long as it’s so low, it’s been difficult to convince anyone that we’re not in a drought … and that goes for everywhere in Florida.

And consider that The Lake has only received 14 inches of rain since the start of June, and only 7 inches over the past 30 days.

That may seem low compared to other areas, but it’s actually a normal dose of summer rains over The Lake. The Lake’s 10-year average rainfall for June is only 7 inches, and for July its only 6 inches.

The reason?

The Lake’s large surface of cooler open water stifles the daytime heating of the land surface and convectional rise of air that brings the rest of the peninsula it’s afternoon rain showers.

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That effect is shown in the photo below for a smaller Florida Lake. By mid-morning, convectional uplift of air is forming popcorn-size cumulus clouds fairly uniformly across the sky pretty much everywhere … except for over the lake. But remember: the Lake only gets a quarter of its annual water from rain. A full half comes in the form of surface water discharge from the Kissimmee River, and the other quarter comes from the other tributaries.

How much has it rained on the Lower Kissimmee in comparison?

It’s received 20 inches of rain since the start of June, and 12 inches in July alone.

That has the Kissimmee River up and flowing at 2,000 cfs into The Lake (from S65E), a flow rate that has been matched by Harney Creek Canal (s71) for the past few weeks.

So far this year, the Kissimmee River has discharged around 300,000 acre feet into the Lake. That’s already exceeded last year’s full-year total … but its low compared to 2005, when 1.4 million acre feet discharged into The Lake through the start of August, and 2.3 million acre-feet for the full year.

In summary, The Lake has risen almost 2 ft since the middle of June, but it’s still hovering a few inches below the 11 ft mark. Eleven feet is the level above which the wetting fronts starts to move its way up into the littoral zone, and also a level it’s been below for over 510 days and counting.

The littoral zone doesn’t become fully flooded from levee bank to levee bank until it rises above 15 ft msl. That hasn’t occurred since early winter of 2006.

And don’t forget the new LORSS regulation schedule is in effect. It designates levels above 17.5 ft to be detrimental to the integrity of the levee.

Compare that to the Lake’s historic level of 20-22 ft above sea level. The littoral zone as we know it today — spanning for miles (more than the eye can see) to the east of Moore Haven — didn’t exist.
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Back then, the littoral zone was flooded with several feet of water, with the open waters of The Lake lapping up to and into the sawgrass plain, feeding a constant stream of water into the River of Grass below.

That sawgrass plain is gone today.

The land where it grew has dropped in elevation on an order of ten feet through drainage of the peat, its gradual oxidation, and agricultural practices.

It’s that drop in land that is the cause of alarm when the Lake’s waters rise too high up against the sides of its perimeter levee: most recently, its brief glimpse above the 18 ft mark after Jeanne in 2004.

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(Ironically, The Lake’s most recent sustained stay above 18 ft occurred during the spring dry season of 1998 as a result of an El Nino.)

But potential acquisition of the 187,000 acres (240 square miles) of US Sugar lands south of The Lake opens the door for a complete re-think of how waters to and from the Lake are managed, and integrated into Everglades Restoration efforts below.

Is it the missing link to the hydrologic system of old?
Grand visions of a flow way live on.

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But the next baby step for The Lake is to get above the 11 ft mark.