Miami Beach wades into sea level rise
By Scott Blake
There may be more pressing matters in Miami Beach, but perhaps none more ominous than the projections for rising sea levels laid out last week during a meeting at City Hall.
Engineering consultants hired by the city are projecting that local sea levels will rise about 4.5 inches over the next 20 years. That's the intermediate projection — the low projection calls for a rise of less than three inches and the high projection calls for a rise of more than six inches.
The issue is being addressed as part of the city's efforts to update its storm water management master plan, which for the first time is taking into account climate change and rising sea levels, to prepare for the future.
For the short term, or about the next 20 years, consultants are recommending the city spend about $206 million on projects to stem the rising seas, such as backflow preventers, more pump stations, raised seawalls and storm water storage.
"The city will need to monitor the rate of sea level rise and adjust the plan accordingly," interim City Manager Kathie Brooks wrote in a letter this week to the city's Finance and Citywide Projects Committee, which was expected to discuss the issue during its meeting Wednesday.
"As sea level rises," she added, "the storm water system will rely more on pumps, and as the existing pumps age, they will be replaced by larger pumps."
Representatives from CDM Smith, a Boston-based engineering and consulting firm, and Coastal Systems International, a Coral Gables-based engineering and marine environmental firm, made presentations on the issue at Friday's workshop.
Even more foreboding than the 20-year forecast is the 100-year forecast, which includes an intermediate projection that local sea levels will rise by about 3.7 feet.
Under that scenario, Miami Beach could still be habitable, although it would look like a much different place, with built-up ground levels, high seawalls and a system of locks for water control, according to one consultant, who asked not to be named, citing a city policy to channel information for publication on the issue through City Hall.
The consultant said the projections were developed using historical data of sea levels, while considering other factors such as global warming and continental shifting.
Of the recommended $206 million in storm water management improvements, the consultants suggested the most — about $106 million — would be needed for the Flamingo Park area and nearby parts of South Beach.
The second-largest amount, $20 million, would be needed on Normandy Isle in the northern part of Miami Beach, the consultants found.
Miami Beach resident Frank Del Vecchio, who attended Friday's meeting and closely follows city affairs, said, after discussing the issue with experts, he thinks the consultants' projections for sea level rise may be too conservative.
Mr. Del Vecchio said extending the cost projections for the city's storm water management plan over 30 years would make more sense, given that pumps and other equipment would have a useful life of more than 20 years.
"If the City of Miami Beach came out with a more realistic [sea level rise] scenario, which would be revealed in a 30-year [sea level rise] projection, it would be authoritative, not like global warming whistle-blowers who can be marginalized," he wrote in an email to Miami Today.
The city seems to have granted his wish.
In an email Tuesday to Mr. Del Vecchio, Ms. Brooks said she has directed the city's public works staff and CDM Smith to also evaluate the city's storm water management costs over 30 years, in addition to the original 20-year estimate.
"It will be as or more important," she wrote, "to continue to monitor studies and information as they become available and have the flexibility to incorporate these changing conditions into future updates of the plan."
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