By: Engr. Edgar Mana-ay
COLORADO SPRINGS, Colorado, USA – In the southern portion of the state of Florida lies a swath of wetlands (swamp in our lingo) whose original area during the 1800s was about 100 km wide by 180 km long.
These wetlands discharge water to Florida Bay from a vast, shallow Lake Okeechobee (with an area of 1,900 square km and an average depth of only 9 feet) which in turn is being fed by Kissimmee, Caloosahatchee, Myakka, and Pease rivers in Central Florida.
While the wetlands serve as a major water drainage for the State of Florida towards Florida Bay, the movement of water is very slow, almost imperceptible, traveling at less than a kilometer a day. This is because the gradient from Lake Okeechobee is only two inches per mile distance towards Florida Bay, thus the water leaving the lake may take a year or more to reach its final destination.
In hydrology, this slow movement of broad, shallow water is called sheet flow and gives the Everglades its nickname as the river of grass because of the 5- to 10-foot-tall saw grass inhabiting the marshland. This is part of a complex system of an inter-independent ecosystem that includes cypress swamps, estuarine mangrove forests, tropical hardwood hemlocks, and the marine environment of Florida Bay – its last water destination.
Fluctuating sea levels 25 to 79 million years ago compressed numerous layers of calcium carbonates (CaCO3), sands and shells, creating a permeable limestone formation now known as the Florida Aquifer, which serves as the main source of underground water supply for the northern portion of Florida. But this aquifer strata dips steeply towards Florida Bay and at the area where the Everglades is located. It is now covered by an impermeable sedimentary rock under the peat basement of the marsh areas, so that the surface water in the marshes cannot infiltrate the ground towards the limestone aquifer. Hence, almost all surface waters will flow slowly towards Florida Bay.
To the 19th century Floridians, all that water – and the mosquitoes and reptiles in the marshes – represented an impediment to progress. When Florida became a state in 1845, one of the legislature’s first acts was to pass a resolution asking Congress to survey the “wholly valueless” Everglades “with a view to reclamation.” Since the 1800s, a host of entities set about draining the swamp, mostly to reclaim it for sugar plantation, making Florida one of the major sugar suppliers for North America. Canals were dug carrying nutrient-laden water that altered the salinity of coastal estuaries and caused toxic algae bloom. The vast custard apple forest on the lake’s southern shore was torched.
The trifling continued until 1928 when a hurricane overwhelmed a dike at Lake Okeechobee causing a torrential flood that killed 3,000 people. The resulting 143 mile, 30 foot high Herbert Hoover Dike now completely surrounds the lake, permanently severing its connection to the marsh park.
Today, the marsh park (also a scene for various movies like Miami Vice where characters use the airboat whose propeller is like a giant fan above the boat) peat mat basement has collapsed by a foot – exposing the roots of grasses and trees. Scientists blame this on encroaching seawater because the freshwater level of the marshland has gone down.
It was only RECENTLY that the Floridians understood that had they not mangled and mutilated a natural ecosystem such as their Everglades, it could have provided enormous benefits such as potable and irrigation water supply and filtration, nurseries for fish and other wildlife, protection from storm surges, ability to act as a carbon sink, and most importantly a tourist attraction.
That has now diminished because of dirty, limited, and shallow marsh water.
Nearly two decades and $4 billion into the Comprehensive Everglades Restoration Plan, an ambitious federal-state program adapted in 2000, data about the pace of climate change have called into question how much of the Everglades can be restored. Part of the restoration program is the Aquifer Storage and Recovery (ASR), which is to drill a series of large holes into the confined aquifer as explained above during the rainy season to store the rainwater before it drains into the sea. During the dry season, the same water stored in the aquifer is pumped out to maintain an ecological freshwater level (now diminishing) in the Everglades. Scientists estimate that more than 650 billion gallons of fresh water a year once flowed south into what is now the national park. Today, that flow is about 280 billion gallons.
On a smaller scale, we have our own Everglades in Iloilo City that we have mutilated and made to disappear. Almost all of our flood plains and swamp areas in the city have been reclaimed for subdivision and housing purposes. A classic example is the mangrove area at the foot of Drilon Bridge, which is now a subdivision for the affluent. We are strangers to Low Impact Development (LID), which is to maintain the SAME hydro and geology conditions BEFORE and AFTER development. In Pavia, there are now 27 subdivisions in what was once rice fields where rain infiltration can go as high as 30%. Since the local government FAILED to impose hydrogeological conditions or LID, such as a series of aesthetic settling ponds, permeable surfaces, rain infiltration now is only 8% resulting in frequent floods.
Lucky for us, we have a Senator Drilon, who has saved the mangroves along the creeks and rivers only because of his Esplanade Project. But what about the pocket and sporadic wet lands, flood plains, and mangrove areas at other places like Villa, Barrio Obrero and others. No one else has the interest to protect and preserve them. We need this sober thought from Robert Lynd: “There is nothing in which the birds differ more from man than the way in which they can build and yet leave a landscape as it was before.”
