So, this post is about our ‘serious’ Florida experience, dedicated to those who are eager to know more about the water management in this tropical State. It’s worth to mention that this experience had been possible thanks to the UNESCO-IHE Florida Program and its principal supporter to whom we express our best gratitude for this unique occasion: thank you Stan Bronson and Florida Earth Foundation!
The main aim of the fieldtrip was to expand our knowledge in models, not the pretty fashion models, but mathematical algorithms at the service of this planet’s and its people’s wellness. The subliminal message, not clearly stated, was ‘it’s so easy to mess up things, but it’s incredibly expensive to make order again’. And sometimes, there are also unintended consequences of ones actions, which instead of improving the system just make it worse. Everything here is oriented towards our most important resource: water. We need it, and as it is part of a big system (the hydrological cycle) if you modify it, you don’t actually know how it would react. Now they know it, they explained it to us, and we would like to tell you this story.
The South Florida is an immense watershed, where the topography is mainly flat, with some exceptions in the northern part (hills not higher than 100m). In this area our story begins: a chain of lakes is the starting point of the system, when the rainy season comes (end of May until October) this region receives a massive amount of water that flows towards the main river, called Kissimmee. This Indian-named river, dives into a gigantic lake: Okeechobee, Indian-named as well. With dimensions 60 km times 50 km but only 3 meters deep on average. Despite the monster size, the local topography doesn’t help to keep the water levels down during the rainy season. So? What used to happen? It used to flood…. towards South, to be precise. The inundation used to take place on a large front, forming a slow but abundant motion with a speed of only few hundreds of meters per day. This is called “sheet flood”, and it is basically a huge river, the only true outlet of Lake Okeechobee. This phenomena has created a swampy environment, what we call today The Everglades.
The white man arrives. He likes the warm Floridian weather, and he likes even more such abundance of timber. In fact it used to be a never ending area of cypresses, a primary forest, close to the Everglades. He decides that the place is good to settle down, creating villages growing fast like a plague, especially on the east coast, where Miami is located. “Hey hey, do you know what we’re gonna do, John?”. “No Sam, go ahead!”. “Here we have to chop some trees, while there we’re going to dredge, joining lake Okee and the Ocean, and then we can sell this timber to the Yankee! Yeeee-ah!”. We’re at the end of 1800s, not so long time ago. The first environment modification that has brought its devastating effects. “Dammed! John we are rich like hell! But in this swamp there’s too much water! We must drain it, so we can capitalize with agriculture and pasture and kick-out this annoying Seminoles!”. “That’s a great idea Sam! Our descendants can have a king size pop-corn bucket drinking a good gallon of milk!”. Dig. Dig more and more. All around lake Okeechobee dry land arises. But this land is not composed of minerals, it is peat. And if peat is not wet, of course it dries. If it’s dry, it burns. Few lightings were enough to light up fires able to destroy large areas. For many years. “Ok John, maybe let’s drain a bit less!”.
Settlements are increasing in number, having a house around lake Okeechobee means a lot in term of monetary values and wellness. Tropical country. Instable climate. Hurricanes. Two in a row. We are now in 1926 and 1928. The placid lake Okeechobee is like an impetuous ocean. With such a shallow depth it behaves like a trampoline for kind of tsunami waves. Thousands of deaths. “Hey, John. Never again. This lake has to be stopped”. Year 1938, lake Okeechobee has a belt of dikes all around that will soon surround all the perimeter. Ok but now how does the water go out? “Don’t worry John, we are gonna build 4 canals to water our crops in the southern part, and with other two canals we join the two costs of Florida, in this way we are sure that lake is not overtopping the levees”. Well done Sam, great engineering solution. It’s such a pity that you are throwing away 6.5 cubic millions of freshwater. Every day.
Do you remember about the Kissimmee River? It used to be an amazing meandering river, with a large floodplain rich of flora and fauna. Wading birds, alligators, Florida panther, just to mention some. Looking for new grazing lands and with the threat of floods, a big project: “Let’s make a straight canal, dredging and expanding the width so that we have a higher capacity eliminating flood hazard. Then we can convert the floodplain in pasture and we’re going to have a way more beef burgers!!”. The project was developed and finished between 1962 and 1971. Even before the end, the technicians who built it recognized the error. There wasn’t fish anymore. The new river cross section, a big rectangle, couldn’t host fish for reproduction. No fish, no birds, no alligators. All of it for cow’s fault!
Talking about cows. Do you know what they do very well except ruminating? THEY SHIT A LOT! And if all of them shit happily together in the same place, they produce a mountain of poo. “Oh shit what a mountain of phosphorous!!”, the environmental scientist says. All of this phosphorous, in such a high concentration, is a pollutant. And where does it go? It is washed from soil and it is transported towards our beloved lake Okeechobee! Poor lake, it cannot flood anymore and it is even ran over by a wave of shit! But we have learnt that the water from the lake has to go somewhere. From the two lateral outlets towards the sea and from the four agricultural canals on the southern side. If this water full of pollutions goes in delicate ecosystem such as estuaries, it destroys everything! No oysters, no seaweed, no manatees (sea cow) and algae explosion! And the water the goes southward from the lake? Towards the crops? Well, it’s not a bad thing to have all of this nutrient. But not all of the phosphorous is lost here, a large amount reaches the Everglades, threatening the local arboreal species!
Every action brings a consequence. If you reduce the water flowing towards the Everglades, what you get is that the swampy area loses water, with a direct drawdown of the water level that doesn’t come up anymore above the surface. Do you have in mind the communicant vases? Well, they work even in Florida: one vase is the submerged land, where there is the swamp, and the other one is the ocean side. The carsick soil is so porous that the filtration velocity is extremely high. And if in the swamp the water level goes down and down, it can be lower than the ocean elevation! And what happens? Inversion of the water motion! Not anymore from land to ocean, but the other way around! “Houston we have a problem”. It is called saltwater intrusion, and when in Miami they started to suck out from wells saltwater instead of freshwater, they figured there was something wrong!
This is the South Florida story. It’s a disaster. Water interests related to social and economic growth have brought to a chain-reaction that looks like a nightmare. “Dude, I think we have messed up, yo!” (We are now in modern times).
So, summing up the things we have said so far.
- Draining system and lake canals are responsible of a large loss of freshwater that doesn’t go the Everglades ecosystem and it is neither available for human needs as it doesn’t fill the groundwater.
- Lake Okeechobee doesn’t flood anymore, being unable to provide water to the system.
- Kissimmee River has become a straight artificial canal.
- Phosphorous concentration at crazy levels into lake Okeechobee and consequently at the estuaries and agricultural lands.
- Saltwater intrusion on the east coast.
That’s indeed a mess. National laws and stakeholder opinions stated that this situation is not sustainable. We have to recover it! Yes but how? Any ideas? This is what they have done.
In order to solve the saltwater intrusion, theoretically it’s enough to invert again the flow motion towards the sea. “That is easy: let’s regenerate again the swamp!”. “Ok dude, but how to join this idea with the heavy populated settlements nearby?”. “Just put dikes, maybe it’s not such a beauty to see, but at least it works!”. This solution has lead to the creation of the so called ‘Water Conservation Areas’ (three in total). Immense restored swamps with monitored water level in order to control and keep the filtration towards the right side.
Phosphorous concentration at stratospheric levels. “What can we do?”. “We can treat it, but let’s do it in the best way: phytodepuration!”. The Stormwater Treatment Areas are again swampy lands, surrounded by dikes, with a domination of a particular species of plant that ‘eat’ the phosphorous. But this leads to a little problem: the pollutant is then kept by plants that are going to accumulate, forming a massive deposit. This solution is hence a temporary answer to the problem.
After a long environmental struggle, one third of the Kissimmee river is going to be restored as it used to be before the channelization. The Kissimmee River Restoration Project is an impressive work of filling up the dug canal and divert the river into the old branches. Thinking about the cost is crazy: 500 millions of dollars to restore a thing back as it was before. Amazing results by the way!
And finally, dear Everglades in need of water, how can we increase the flow in order to get back to a situation close to the one had 100 years ago? Canals and dikes removal are waiting to be done, underground and surface stormwater retention basins are already a solution! And now the question: but how do models fit in this story? Well…how do you think they have simulated and evaluated the best solutions in future scenarios?
We learn from our mistakes. And we have learnt very good indeed.