The meaning of dry caves

Posted on May 22, 2012

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FL005

The caves in Hernando County, Florida are drying out.

Hernando County is about an hour north of Tampa. It’s definitely cave country. But it’s also been losing its rural character and becoming more and more suburban over the last fifteen years or so. And that’s most likely part of the reason the caves are drying out.

That’s because with suburbs come subdivisions. Subdivisions bring lawns, sprinkler systems, and deed restrictions that require a certain level of lawn maintenance. That means lots of water. Suburbs also sometimes bring golf courses, which also have massive water needs.

Historically, Florida’s been a pretty rainy place, at least in the summertime, so our preference for lush, green lawns wasn’t always a problem. But it seems we’ve been experiencing a drying trend lately: average annual rainfalls have been falling since the 1990s … but our preference for suburban living (and all that it entails) hasn’t really abated.

So we need water, and it isn’t falling from the sky like it used to. Luckily for us, there’s another place we can find the water we need – underground. By pumping water from the aquifer, we can still enjoy the same lifestyle we always have here in the Sunshine State, without having to make any sacrifices.

Of course, that will only get you so far, since that groundwater was at one point rainwater itself. If it’s not raining enough, the aquifer is not being replenished enough, which means the groundwater level will fall further and further.

Down in eastern Hillsborough County, there have been times when excessive groundwater pumping (usually when strawberry growers need to water their crops overnight during the occasional January or February freeze) have actually led to sinkholes opening up nearby. By pumping so much water from the aquifer so quickly, growers lowered the hydrostatic pressure, which means that there just wasn’t anything preventing the ground from collapsing in on itself in certain “weak spots.”

And there’s yet another wrinkle for coastal areas like Hernando County. When we take too much fresh water from the aquifer, the lower hydrostatic pressure makes the aquifer vulnerable to salt water intrusion from the Gulf of Mexico – in other words, salt water seeps into places where we’re used to finding fresh water.

The drought causes us to pump more groundwater. Pumping more groundwater causes things to dry up, like caves and wetlands. And the trick of it all is that drying out wetlands may actually work to exacerbate the drought, since water first has to  evaporate before it can fall back to earth as rain.

What’s happening in the caves up there in Hernando County should serve as a wake-up call for us here in Florida. We need to shift our mentality and our lifestyle expectations, and embrace a more urban way of life. We can’t keep living like the water won’t ever run out, because it’s already starting to.

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Posted in: environment, karst