Miami Outlines $4B Plan to Fight Rising Sea
The City of Miami has recently completed its updates on its Stormwater Master Plan, a comprehensive assessment of the city’s roads, drainage infrastructure and water management features to identify improvements needed to address capacity and flooding issues.
The final plan covers nearly $4 billion in spending over the next 40 years in an effort to keep the city dry from rising seas, with some of its recommendations to be included in the city’s Capital Improvement Plan, which considers changing climactic patterns, sea level rise, and the desire to strengthen the resiliency of Miami.
However, reports claim the money and proposed projects won’t be enough to save every neighborhood.
About the SWMP
According to an Executive Summary regarding the SWMP, the city has planned for the initial funding of projects that will mitigate flooding, protect and enhance the water quality of Biscayne Bay, and strengthen the shorelines from tidal storm inundation.
Work on the plan was reported to have launched two years ago in 2019 when sea levels were expected to rise 18-30 inches by 2070. However, those predictions have since increased, now predicting that the sea levels would rise that high 20 years sooner in 2050.
“The most common question I get asked is whether Miami is going to be here in 50 years, whether it’s going to be here in 100 years,” said Miami Mayor Frances Suarez while announcing the release of the report in March. “This is the beginning of having a comprehensive plan to answer that question in the affirmative.”
The SWRP involved a series of studies, analyzation of data and recommendations made by engineers to create the collection of planning-level costs for capital projects. The plan also considered design storm flooding predictions using stormwater models simulating topography and land use, the physical attributes of the stormwater management system, controls and limitations, and the runoff generated by rainfall, in order to properly identify deficiencies and recommend corrective actions.
“There are some areas where you run the model now and you plug in the recommended pump stations and outfalls and wells, you will find minimal to no change with hundreds of millions of infrastructure,” said Chris Bennett, the city’s deputy chief resilience officer. “There are cases where your engineering solutions just won’t provide you any benefit.”
The simulations were identified by Miami-Dade County 311 flooding complaint system, the Federal Emergency Management Agency repetitive loss system, as well as from Flood Insurance Rate Maps (FIRMs) and other reported flooding complaints.
As a whole, the SWMP provides:
The city notes that the end result is a cost-benefit balanced suite of both conventional and innovative approaches, which utilizes the natural environment as an asset, and protects Biscayne Bay. From here, the project is divided into four major work phases including a data collection and evaluation phase, stormwater modeling phases, a seal level rise evaluation and resiliency considerations phase and a capital improvement program phase.
For the $3.8 billion the city plans to spend over the next four decades, the City of Miami intends to purchase at least 93 new mega stormwater pumps (the city currently has 13), miles of six-foot-tall seawalls, thousands of injection wells, as well as a network of underground pipes which would expand the sizes from roughly three to four feet wide to eight feet wide. The SWMP also mentions the “eventual requirement” of flood walls and water barriers at the mouths of rivers and canals—a part of the Army Corps of Engineers’ $6 billion plan to protect the county from future storm surge.
In addition, the plan also hints at more futuristic-type projects such as floating cities and converting roads to canals.
Not so futuristic, though, the plan mentions of making the city greener and cutting down pollution through the installation of more parks and landscaped areas, which would also aid in soaking up rainwater and lessen the burden on Miami’s water infrastructure.
To decide on what level of protection city planners wanted to prepare for, they observed “1-in-5 year” and “1-in-10 year” storms. While building to a 10-year storm standard would offer more protection (estimated to cause 11 inches of rain over a three-day period), it could cost up to $5.1 billion, compared to the $3.8 billion five-year plan (estimated to cause seven inches of rain over one day).
“The goal is 10-year level of service anywhere we can, but the minimum standard is a 5-year level of service, which in some neighborhoods is a significant improvement to what we have now,” said Miami Chief Resilience Officer Alan Dodd.
Dodd added that to not impact the Biscayne Bay, the city will also need additional filters at pump stations to remove pieces of trash, oil and grease and filter out pollutants like nitrogen, phosphorus and bacteria found in poop.
To pay for the series of projects, the report suggests grants and the combination of state and federal funding, in addition to partnerships with private companies. Although, another issue with the plan is that the $3.8 billion outlined, does not include maintenance cost and would have to be contracted out. Should the city fail to get the proper funding, the Miami Herald points out that the estimated cost of adaptation is four times the city’s annual budget, and with about $175 million left in the Miami Forever Bond dedicated to sea level rise projects.
For the first slew of projects, which are expected to be completed within the next five to 10 years, are expected to cost $545 million if done at the lower level of protection. The estimated cost for those same projects at the higher level of protection, however, is $911 million.
Miami-Dade hasn’t yet made a final decision on whether to allow the plan to move forward as it stands so the Corps can get it approved and funded, or whether to ask for more time.
A decision is expected in the next few months.
Throughout the rest of April and May, the city will also be hosting a series of virtual community meetings to update residents on the City’s 2021 SWMP report.
Seawall, Flood Barrier Plans for Coastal Communities
No longer a debatable issue, many cities have begun planning for the construction of flood barriers, seawalls, and other methods to fight rising sea levels.
In May of last year, the Army Corps of Engineers announced the preliminary proposal of a $1.75 billion seawall around the lower Charleston Peninsula in South Carolina. However, with possible variations, the cost of the seawall could inflate to as much as $2.2 billion.
Reports indicate that if built, the seawall would measure nine-miles-long and stand 12-feet-tall, consisting of two primary sections: an overland concrete barrier located along the eastern side of the peninsula from downtown to the Neck, and a metal barrier—called a combo wall—that would run through marsh and nearshore areas along the western side of the peninsula, in addition to a small portion on the eastern side.
Later that year, in October, New York City Mayor Bill de Blasio and Gov. Andrew Cuomo announced that construction on a $336 million coastal resiliency project was officially kicking off. According to reports, the shorefront project involves the construction of six miles of storm surge flood protection along the Queens waterfront. However, the first phase of the project will see the building out and restoration of nearly 20 stone groin structures—similar to rock jetties—into the ocean to prevent additional sand erosion.
The rehabilitation and construction of these flood barriers are expected to provide stabilization for a re-nourished sand beach and dune and maintain the protective beach profile, as well as help to restore local ecosystems and ensure the long-term viability of endangered species.
Following these efforts, crews intend to reinforce a network of dunes with stone and steel sheet pile walls, achieving a height two feet higher than the original structure, and further protecting the coast from wave breaking pressure. The new structures are also slated to limit surge inundation and cross-peninsula flooding.
The following month, the Corps and the Texas General Land Office released a second draft of its envisioned multi-billion-dollar coastal storm barrier, Ike Dike. Plans for the barrier have reportedly been in the works since Hurricane Ike rocked Galveston, Texas, in 2008, and are expected to cost anywhere between $23 billion to $32 billion.
The Ike Dike barrier would consist of a system of levees and sea gates beginning north of High Island, running along Bolivar Peninsula. The coastal barrier would also wind its way across the entrance of Galveston Bay and run the length of Galveston Island, eventually including the pre-existing seawall, ending at San Luis Pass.
At the bay’s entrance a series of storm surge gates would accommodate navigation to a few ports, namely Galveston’s, Texas City’s and Houston’s. A navigation gate, located along the Houston Ship Channel, would close during storms. Galveston would be protected with a ring levee shielding the rear of the island.
Other plans for the Ike Dike include beach and dune restoration along the lower Texas coast. Nine ecosystem restoration projects are also in the works to help increase area resilience.
Noting on the project’s revisions, one of the biggest changes involves the replacement of a series of levees and floodways previously slated to run parallel to State Highway 87 on Bolivar Peninsula and FM 3005 on Galveston Island with 43 miles of a natural dune and beach system.
The system is reportedly comprised of 14-foot dunes on the landward side and 12-foot dunes on the Gulf, followed by 250 of beach. While the Corps notes that the change will reduce environmental and social impacts, it would also require about 39 million cubic yards of sand for beach and dune construction on both Bolivar Peninsula and West Galveston Island.
Other changes to the project proposal involve updating the storm surge gate between Galveston and Bolivar Peninsula to two 650-foot-wide surge gates at the mouth of Galveston Bay, instead of the initially proposed 1,200-foot wide gate. Although the change would reduce the water flow by 10%, the Corps estimates that design change has less of an impact on restricting the flow of water between the bay and the Gulf than previously proposed, adding that the gates would only be closed during the event of a storm.
In a study conducted by Stanford University at the beginning of the year, researchers found that the United States has spent nearly $199 billion in flood damages over the last three decades. However, researchers went a step further than just comprising a spending report and further indicated that the flooding experienced from 1988 to 2017 as a result of intensifying precipitation—consistent with predictions of global warming—was responsible for one-third ($75 billion) of the total financial costs.
To settle the debate of how much climate change has actually contributed to the rising financial costs of flooding—the most common, widespread, and costly natural hazards—researchers looked at socioeconomic factors like population growth, housing development and increasing property values, in addition to correlations between precipitation and flood damages.
Previously, the university noted that other studies focused either on very detailed case studies or just participation correlations.
To start, researchers looked at higher resolution climate and socioeconomic data where they applied advanced methods from economics to quantify the relationship between historical precipitation variations and historical flooding costs. The research team also looked at methods from statistics and climate science to evaluate the impact of changes in precipitation on total flooding costs.
As a result, the analyses showed that not only did climate change contribute substantially to the growing cost of flooding in the U.S., but that if the nation were to exceed the levels of global warming agreed upon in the United Nations Paris Agreement, the effects would only grow and continue to worsen.
To further isolate changing precipitation as the primary root of increased national flooding, researchers developed an economic model based on observed precipitation and monthly reports of flood damage. In their model, researchers controlled other factors that might affect flooding costs like increases in home values, and then calculated the change in extreme precipitation in each state over the study period. As a result, the team was then able to use the model to determine what the economic damages would have been if those changes in extreme precipitation had not occurred.
Through this framework, the team found that changes in precipitation accounted for 36% of the actual flooding costs that occurred in the U.S. from 1988 to 2017 and was primarily driven by increases in extreme precipitation.
Moving forward, the research team hopes that their approach can be used in observing other types of natural hazards and climate impacts against different sectors of the economy and to other regions of the globe to help understand the costs and benefits of climate adaptation and mitigation actions.
