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The splendor of Miami Beach, with its white sands and luxury hotels, makes it hard to imagine that it was once inhospitable swampy terrain.
What was at the beginning of the 20th century only a mangrove island, it is today a symbol of luxury and debauchery.
In recent days, however, Miami Beach has once again made headlines as in the town of Surfside, located on the same island, part of the Champlain Towers South residential building has collapsed at 8777 Collins Avenue.
Monday evening, the collapse left 11 dead and 150 missing.
It is not yet known what caused the collapse of the building, but many questions have been raised about the land on which several buildings in the neighborhood are built.
Experts agree that it is too early to draw conclusions about the collapse, but they also warn that this disaster serves as a warning to remember the vulnerabilities facing one of the most sought-after tourist and residential areas in the world. planet.
Miami Beach is a city of 90,000 inhabitants, which is part of Miami-Dade County, in the south of the state of Florida, United States.
It is an island that has the Atlantic Ocean to the east and Biscayne Bay to the west, which separates it from the city of Miami.
Miami Beach is built on what is called a barrier island, a natural piece of land parallel to the coast.
These types of islands are formed when waves repeatedly deposit sediment in an area near the coast.
Barrier islands are fragile soils, made up of sandy and erodible soils, subjected to the impact of waves.
As the wind and waves change based on weather conditions and local geographic features, these islands are constantly shifting, eroding, and growing and shrinking, according to the U.S. National Oceanic and Atmospheric Administration Office (NOAA).
Although this is not known for sure, it is estimated that barrier islands formed around 18,000 years ago, towards the end of the last ice age.
Today, barrier islands play an important role both for humans and for all nature.
On the one hand, they protect the coasts from the violent impacts of storms, and they are also home to a variety of flora and fauna.
Until 1912, what is now Miami Beach was a barrier island dominated by mangroves.
At this time, several entrepreneurs and investors such as John S. Collins, Carl Fisher and John and James Lummus saw the potential in the island to build a city dedicated to pleasure and luxury by the sea.
With urban development and a bridge connecting it to Miami, Miami Beach, officially founded in 1915, began to receive visitors from all over the country, and today it is a global tourist destination.
Through dredging, builders added more land to the island, which today has an area of 19 km².
The eastern part of the city, which is higher, is mainly built on limestone, organic fill and sand.
The western part is elevated mainly on wetlands that have been filled in, with which the mangrove has been destroyed.
“Crearon terreno from algo que era unhabitable o que ni siquiera estaba ahí, y construyeron encima de ello”, the dice a BBC Mundo el geólogo Randall Parkinson, investigador de áreas costeras in the Universidad Internacional de Florida (FIU, por sus siglas in English).
Parkinson’s, however, warns that Miami Beach’s terrain can vary widely across the island.
“Some areas of Miami Beach are sand dunes and beach ridges; other areas are a mixture of sand and organic matter from mangroves; and other areas are just organic matter. , there may or may not be lime, ”says Parkinson. .
The western area of the city does not rest on very solid rocks, which is why there is more and more subsidence and flooding in this part of the island, as explained by geologist Shimon Wdowinski. , expert in spatial geodesy, in a recent interview. at BBC Mundo FIU Natural hazards and sea level rise.
For its part, in the eastern area of Surfside, where the collapsed building was located, there is a very porous limestone with a low elevation, explains Wdowinski.
Either way, Parkinson’s insists the terrain can vary widely.
“What is under one building may not be under another,” he says.
“That said, two buildings side by side are more likely to have similar soil and sediment under them than two buildings one kilometer apart.”
The construction of buildings and roads on a barrier island can affect its natural dynamics, says Anna Linhoss, professor of bioengineering at Mississippi State University, in an article published in The Conversation.
He mentions, for example, that the construction of piers and jetties can interrupt the flow of sand on the island, thus blocking the flow of sediment in certain areas, which are prone to erosion.
The terrain, location, climate change and urbanization of Miami Beach are already posing great challenges to the island.
Parkinson mentions that among the reasons that have been discussed for the fall of the building are sea level rise, saline intrusion and subsidence.
Saline intrusion refers to seawater that enters under the frame, which can generate, for example, flooding in the lower part of the frames.
Subsidence, on the other hand, refers to subsidence of the land.
In 2020, Wdowinski published a study that detected sag of up to 2 millimeters (mm) per year in the area where the Champlain South Towers are located.
However, the expert specifies that this alone does not explain the collapse.
But Parkinson’s point of view is that while they may not be the exact causes, climate change is causing sea level rise and saline intrusion; and urban development can generate subsidence.
The island can also be severely affected by sea level rise as it could generate more high category hurricanes.
“Miami Beach faces the same challenges as any other barrier island in the world,” Harold Wanless, professor in the FIU’s geography and sustainability department, told BBC Mundo.
“There is a good chance that in the next 20 or 30 years we will have a sea level rise of between 60 cm and 90 cm due to the acceleration of the melting of the poles.”
According to Wanless, that would mean residents of South Florida would lose access to fresh water, treatment plants would cease to operate, and large areas would remain constantly inundated.
Miami Beach, for example, would remain largely abandoned.
“Living there will end throughout this century,” says the expert.
“It is an extreme concern.”
Parkinson agrees, adding that it will be a “getting worse and worse” problem.
Millions of dollars have been invested in Miami Beach to address these challenges.
Pumping and drainage systems were constructed and elevated roads were constructed.
Experts warn, however, that the challenge is enormous.
“We pretend it will be just a little [el aumento del nivel del mar] and that we can stop it, but we can’t stop it because we are warming the ocean, ”says Walness.
“What happened at the Champlain Towers may not have to do with the rise in sea level, but it shows the need to start talking about it, because it is something that we are facing “says Walness.
“For a long time, we acted like there was no problem, with the attitude of building without worry.”
“We must not only look at how we are going to build in the future, but also the older buildings which will be affected by the rise in sea level.”
And when it comes to Miami Beach’s future, Walness has a clear conclusion: “The best part is that they come and enjoy it while it still exists.”
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