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The Peril of Peat: Sea Level Rise in South Florida: Part 1

Post by: Ben Wilson

 



Ben Wilson having some fun in the mud

I love mud. Seems like I have for a long time now. It’s squishy and smelly, and once you get a little bit on you, you might as well go all out. I’m lucky in that the two most recent places I’ve lived, coastal Alabama and now in Miami, have had ample areas for me to get my mud fix. However, over the past century those areas have been dramatically decreasing, and given current and future climate change, they may disappear at an even greater rate. Over the next two blog posts, I will tell you how human development has altered water flow in the past, further exacerbating the problem of today: sea level rise. In order to save the mud, we must first look at what caused this problem in the first place.

Drain, baby, Drain


Whole books have been written on why and how the Everglades have been modified and managed, but I will just hit the highlights here. The Everglades as it is today began forming about 5,000 years ago when sea level began to stabilize following the last ice age. During the rainy season, water would spill over the banks of Lake Okeechobee and flow as a sheet down the Florida Peninsula. Beginning in the 1880s and continuing into the 1940s, attempts began to drain the Everglades in order to use its fertile land for agriculture. Canals and dikes were highly successful at shuttling water away from the Everglades. However, this soon caused extensive droughts and fires, leading people to realize that water flow needed to be managed to create the perfect balance of not too much water to flood the crops, but enough to prevent drought.

 As you can see below, all these efforts completely altered the water flowing through the Everglades and threw a stable ecosystem into imbalance. Much less water is getting to the coastal Everglades, and this is becoming a large problem because of the ever growing issue of climate change.

 

Historic water flow (left) versus current water flow as a result of intensive management (right) has led to dramatically less freshwater flowing south. Source Evergladesrestoration.gov

How could it get worse?

Do you know where your drinking water comes from? In south Florida, it comes from the Biscayne Bay aquifer, which is fed by rainwater that flows through the Everglades and seeps below the ground. The head pressure of freshwater aquifer is so great that it can push back saltwater from the ocean and keep it from coming inland. This vast aquifer is one of the reasons why this region has been able to cope with the population boom, now at over 6 million people living in south Florida. Now as you can guess by reading above, altering the flow of freshwater has diminished the aquifer, reducing its size and head pressure. But reduced flow from the north is not the only threat to this aquifer…

Past and predicted future sea level rise.  Source: IPCC (2013).

 

Climate change and the warming associated with it has accelerated sea level rise as oceans expand and arctic glaciers melt. Because there is less freshwater to push the oceans back, saltwater has begun to intrude at greater rates into the aquifer. This is threatening the drinking water supply as the pumping wells in coastal cities are starting to pull up undrinkable brackish water. Recently, some wells in Broward County on the eastern coast had to be abandoned due to saltwater intrusion. As the population continues to grow and seas continue to rise, this problem will only become exacerbated unless action is taken.

 

The zone where saltwater from the ocean and freshwater from the aquifer mix has been moving inland at a rapid pace, causing saltwater intrusion into pumping wells. Source: St. John’s River Water Management District.

 

So now that you know the causes of saltwater intrusion and one of the problems it is producing, I’m sure you are wondering “What about the mud?” and “What can we do to solve this?” Stay tuned for my next post to find out!