Hannah Locke

The city of Tampa’s water system is affected by a variety of growing issues that have increasingly intensified in the last few decades and will continue to if not properly addressed. Tampa’s location on the Gulf Coast of Florida has seen an increase of extreme weather events, including hurricanes, tornadoes and droughts. The increased precipitation from major storms, combined with population growth has resulted in increased pressure on the city’s water management system, especially on its wastewater system. The excess water quickly overwhelms the sewers leading to city wide flooding and wastewater overflows. Throughout the region there has been declines in water quality from various forms of pollution, notably human and industrial wastewater. The last major problem is saltwater intrusion into the groundwater potentially contaminating one of the city’s sources of drinking water. All the problems mentioned are only exacerbated by the region’s vulnerability to climate change and sea level rise. The city’s infrastructure and management style have not been designed effectively for climate change resilience and adaptation.

These problem areas reflect a need for increased stormwater management as the city continuously faces significant flooding year after year. Based on the city’s existing infrastructure, hydrological features, geographical features, meteorological conditions and social characteristics a combination of green stormwater infrastructure (GSI), blue infrastructure and nature-based solutions are required to properly address the city’s stormwater.

Tampa’s existing GSI is fairly limited with only four official projects of bioretention street trees and permeable pavements (City of Tampa 2021). Tampa has a growing urban population and as the city grows it should balance its residential and commercial development with green spaces. Tampa is in the beginning stages of implementing more extensive GSI, having received a $36.6 million bond to expand GSI for long-term stormwater management and climate change resiliency. This bond was only recently allocated in October of 2021 so the specifics of the project have not been released other than that the projects will be centralized around the city’s central and lower basins (Loizou 2021). The project would ideally focus on reducing the impacts of flooding in the city through rain gardens, permeable pavements, gravel storage reservoir, bioswales and bioretention soils and vegetation.

These types of GSI have numerous benefits of absorbing excess water, filtering pollutants and reducing sewer system overflows. Rain gardens implemented adjacent to streets, houses or commercial real estate are a cost-effective method of rainwater and surface runoff collection that is not only functional but visually appealing (EPA 2021). Permeable pavements are used in replacement of concrete or asphalt because it’s highly porous, allowing water to flow through the pavement and into the ground (GBA 2021) (Image 1). Similarly gravel storage reservoir are another method of underground stormwater storage that reduces runoff volumes and flow speeds (City of Tampa 2021). Bioswales relieve some pressure off the sewer system by absorbing low flows and moving stormwater into surface water sources (NRCS 2005). Through engineering scientists have created bioretention soils that optimize infiltration rate, improve water quality and support a variety of vegetation and animal species (Tackett 2006). A combination of these various types of GSI will help reduce the impacts of flooding and better prepare the city for excess water brought on by sea level rise.

Green stormwater infrastructure alone will not solve Tampa’s flooding problem, there is simply too much water. The Florida aquifer surrounding the Tampa Bay region is fairly shallow, despite having permeable surfaces there’s only so much water that can be absorbed into the groundwater during storm events (Image 2). This leads to increased flooding of the city and runoff entering the sewers and subsequently overwhelming the system causing combined sewer overflows (CSOs). The city needs to slow the entrance of water into both the sewer system and the groundwater.

A method of storage of runoff and rainwater in this urban environment would be through rooftop water storage cisterns and underground storage tanks. The primary management objectives of cisterns or rain barrels is to reduce water demand and reduce runoff. These rooftop cisterns collect rainwater that can be stored before release into the groundwater or be reused for non-potable purposes, for Tampa specifically, irrigation. Commercial buildings can reduce the runoff that enters the public system by through rainwater collection and reuse for non-potable uses (Image 3). This could be implemented on residential, commercial and industrial properties to reduce the amount of runoff entering the sewer system. The installation of gutters and downspout systems is relatively cost efficient and condensed enough to be easily applicable in urban environments (Un 2016). Putting in underground storage tanks would be a large operation but should be more widely considered in new builds

In addition to the development of manmade infrastructure, Tampa should consider investing in nature-based solutions such as installing aquatic buffers and restoring wetlands and mangroves. Aquatic buffers serve as a natural boundary between waterways and human development, protecting the health of the ecosystem. The buffer effectively reduces pollution from urban runoff, filters stormwater and prevents erosion and sedimentation, stabilizing coastal shorelines (EPA 2002). This would be beneficial specifical to the rivers that flow through Tampa, including the Hillsborough River, Alafia River and Tampa Bypass Canal that are all vital sources of drinking water for the city. The aquatic buffers would not only prevent pollution and contamination to the waterways, but also control and reduce flooding from the rivers. Additionally, aquatic buffers of mangroves and wetlands replacing seawalls and coastal development can assist in reducing the severity of flooding.

Currently the Tampa Bay coastline has a combination of saline tidal marshes and mangrove forests, however those ecosystems are threatened by stormwater flooding and sea level rise. Mangroves and wetlands act as natural coastal defense able to absorb the excess water and energy from storms. Wetlands have numerous benefits for managing stormwater, including improving water quality and flood control and mitigation. This low maintenance option effectively absorbs and filters pollution, increasing sedimentation and decreasing ecological degradation. In terms of flood control, wetlands reduce the intensity of surface runoff by slowing and retaining stormwater, reducing peak velocity during storms and limiting large discharges of water (EPA 1990)(Image 4). The presence of mangroves and wetlands has proven to reduce the risks of loss of life and property damage of regions behind them. Additionally, mangroves bind soil together reducing erosion, which Tampa beaches are suffering from (Spalding et al. 2014). To protect Tampa’s coastline from flooding and sea level rise they should implement a hybridized system of hard infrastructure (sea walls) and a living shoreline (wetlands and mangroves). 

Looking at the bigger picture, stormwater management is about making Tampa adaptable to effects of climate changes. They will experience more extremes in terms of weather and climate, with hurricanes, increased precipitation, sea level rise and droughts. The city needs to be able to handle the excess water, otherwise the continual flooding and sea level rise will make Tampa non-existent in the future. The current city planners have allowed massive urban development of multi-million-dollar apartment and condo buildings, shops and hotels without significant regard for their hurricane and flooding risk. The city of Tampa hasn’t been directly affected by a categorized hurricane in about 100 years, and it has lured the city and its officials into a false sense of security. The intensity and frequency of massive storms is only increasing, and the city can only narrowly avoid serious damage for so long. It’s not a matter of if, but of when and Tampa has not prepared. In situations where Tampa hasn’t been directly hit it still experiences heavy rains and excess flooding, even with category 1 (Fears 2017; NOAA 2021). Officials have recognized that this puts pressure on the city’s sewer collection system but has yet to effectively manage its stormwater.

Hurricane tracking data has shown a rise in the amount and intensity of major storms, with 2021 having a record-breaking year for named hurricanes (Morales and Paybarah 2020). This reality increases the likelihood that Tampa will experience a direct hit from a major hurricane within the near future and the damages will be catastrophic. In the event of category 5 hurricane, Tampa should expect winds speeds up to 156mph, 20 feet or greater storm surges, hundreds of million dollars in damages and more than 2,000 deaths (Image 5). The storm surge inundation would put almost the entirety of Tampa under 20 feet of water, including the city’s wastewater treatment facilities and its desalination plant (Fears 2017). The bigger, long-term problem will be how the city will adapt to excess water brought on by climate change.

While looking at NOAA’s Sea Level Rise Viewer we can get an idea of how the city’s going to be affected by sea level rise and where Tampa’s vulnerabilities are. Looking at just one foot of sea level rise, we can already see where inundation is likely to occur and unfortunately, it’s almost the entirety of Tampa’s coastline as well as inland waterways that are expected to rise (Image 6). Jumping to 5 feet, we see the potential inundation increase significantly with severe flooding excepted on the west coast of the Tampa peninsula (Image 7). At this level we can really see how vulnerable the back bay waterways are and how unideal these locations are for residential and commercial development. Lastly, looking at 10 feet of sea level rise, approximately Tampa will be underwater (Image 8). Inundation from the west coast of the peninsula is extreme, making the city uninhabitable long-term (NOAA 2021). Based on these models Tampa should consider major mitigation intervention to prepare the city for the eventual impacts of sea level rise.

The stormwater management recommendations previously made should be considered short-term and cost-effective options for Tampa but in the long-term major changes to infrastructure and governing practices need to be made. Tampa needs infrastructure advancement of its wastewater treatment facilities and water distribution network to be adaptable to flooding, sea level rise and population increases. Additional updates to hard infrastructure including roadways, bridges and highways. Tampa needs some sort of stabilization of the shoreline to manage coastal erosion and inundation, this will likely require a combination of mangroves, wetlands, sand dunes and seawalls. There needs to be extensive planning and organizing of the city’s evacuation protocols and methods of transporting large groups of people out of the area. Additionally, these protocols need to accommodate the population increases and people evacuating from Pinellas County travelling through Tampa. Based on the current evacuation plans, if a major hurricane was to hit Tampa, people would struggle to evacuate efficiently and safely. Lastly, the city should consider upgrades to building practices and zoning of residential, commercial and industrial properties. Ideally, the city would restrict development of vulnerable areas, however the demand for beach front properties is high. If people are going to live in high-risk locations, those buildings should be required to be both hurricane and flood proof (Tampa Bay Climate Science Advisory Panel 2019; Fears 2017).

There are several improvements necessary to Tampa’s drinking water and wastewater infrastructure to ensure a resilient water network. First option is to raise treatment facilities above the flood line and predicted sea level rise mark, for Tampa that would be in the northern part of the city, outside the primary downtown area. Another option is to relocate vulnerable infrastructure out of the flood zone, currently that would include Tampa’s wastewater treatment facility and its desalination plant that are both located on the coastline. A less attractive, but more cost-effective option would be to erect sea walls or barriers in front of treatment and distribution facilities. Lastly, Tampa could conduct major renovations to its drinking water and wastewater treatment facilities and its pipe network to make them flood proof (The World Bank 2020). All these options would be expensive and time consuming, but ultimately necessary to protect Tampa’s water infrastructure from inevitable flooding and sea level rise.

The primary obstacle for effective stormwater management and climate change resiliency planning is lack of funding and bipartisan support. Republicans have repeatedly blocked proposals from Tampa and Hillsborough County officials to raise the stormwater management taxes to update outdated and failing infrastructure. Unfortunately controlling governments in Tampa are conservative leaning and deny the realities of Tampa’s vulnerabilities to climate change. The current climate change language used by the city’s government is of supporting, modeling and vague planning, but no clear actionable targets and goals. There does appear to be recognition of Tampa’s vulnerability to sea level rise by scientists, nonprofits and private entities but there appears to be a lack of urgency by the government. This sentiment extends to residents of Tampa who continually build million-dollar homes right on the beach with little regard for their flooding risk. The city keeps allowing new builds like this because people will always want to live on the beach, and they are willing to pay for it.

For Tampa to effectively manage its current stormwater as well as prepare for potential natural disasters and sea level rise several intervention actions need to be taken. Soon Tampa could implement green stormwater infrastructure of rain gardens and permeable pavements, blue infrastructure of rooftop cisterns and underground storage tanks and nature-based solutions of aquatic buffers, mangroves and wetlands. In the long-term to prepare for hurricanes and sea level rise the city needs major infrastructure improvements of its water treatment and distribution systems, shoreline management, evacuation and transportation protocols and building practices. Tampa’s water system is extremely vulnerable to excessive flooding brought on by hurricanes and sea level rise, the city needs to take action to ensure its adaptability for the future.

Sources

City of Tampa. (2021). Green Infrastructure. Stormwater Services. https://www.tampa.gov/tss-   stormwater/programs/green-infrastructure

Fears, D. (2017). Tampa Bay’s coming home. The Washington Post.             https://www.washingtonpost.com/graphics/2017/health/environment/tampa-bay-climate-change/

Frago, C. (2020). Tampa studies how to make its stormwater system handle rising seas. Tampa Bay Times. https://www.tampabay.com/news/tampa/2020/03/16/tampa-studies-how-to-make-its-stormwater-system-handle-rising-seas/

Green Building Alliance. (2021). Permeable Pavement. https://www.go-gba.org/resources/green-building-methods/permeable-pavements/

Loizou, C. (2021). A $36.6M bond will establish green infrastructure initiatives in Tampa. WUSF Public Media. https://wusfnews.wusf.usf.edu/environment/2021-10-12/36-6m-bond-set-to-establish-green-infrastructure-initiatives-in-tampa

Morales, C., Paybarah, A. (2020). Eta Thrashes Florida, Again. The New York Times.       https://www.nytimes.com/2020/11/11/us/hurricane-eta.html

National Resources Conservation Service. (2005). Bioswales.             https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_029251.pdf

National Oceanographic and Atmospheric Administration. (2021). Sea Level Rise View. United States Department of Commerce. https://coast.noaa.gov/slr/#/layer/slr/5/-9175608.222144272/3241329.683794309/10/satellite/170/0.8/2050/interHigh/midAccreti on

Spalding, M., McIvor, A., Tonneijck, FH., Tol, S., van Eijk, P. (2014). Mangroves for Coastal Defense: Guidelines for Coastal Managers & Policy Makers. Wetlands International and The Nature Conservancy. https://www.nature.org/media/oceansandcoasts/mangroves-for-coastal-defence.pdf

Tackett, T. (2006). Bioretention Soils. Seattle Public Utilities.        https://depts.washington.edu/uwbg/docs/stormwater/BioretentionSoilSpecs.pdf

Tampa Bay Climate Science Advisory Panel. (2019). Recommended Projections of Sea LevelRise in the Tampa Bay Region. https://www.tbrpc.org/wp-content/uploads/2019/08/CSAP_SLR_Recommendation_2019_Final-1.pdf

The World Bank. (2020). Resilient Water Infrastructure Design Brief. Global Water Security and Sanitation Partnership. https://reliefweb.int/sites/reliefweb.int/files/resources/Resilient%20water%20infrastructure%20design%20brief.pdf

Un, K. (2016). Fact Sheet: Cisterns and Rain Barrels. Metropolitan Area Planning Council.         https://www.mapc.org/resource-library/fact-sheet-cisterns-and-rain-barrels/         

United States Environmental Protection Agency. (2002). Aquatic Buffer Model Ordinance.          https://www.epa.gov/sites/default/files/2015-12/documents/2002_09_19_nps_ordinanceuments_buffer_model_ordinance1.pdf

United States Environmental Protection Agency. (1990). Uses of Wetlands in Stormwater Management. National Service Center for Environmental Publications (NSCEP)

United States Environmental Protection Agency. (2021). Soak Up the Rain: Rain Gardens.           https://www.epa.gov/soakuptherain/soak-rain-rain-gardens

Image Credit

Image 1. Permeable pavement in Tampa. City of Tampa. https://www.tampa.gov/tss-stormwater/programs/green-infrastructure

Image 2. Estimated Transmissivity of the Florida Aquifer System. USGS. https://pubs.er.usgs.gov/publication/pp1807

Image 3. Rainwater Collection System. Water Conditioning and Purification International Magazine. https://wcponline.com/2017/07/15/rainwater-harvesting-stormwater-collection/

Image 4. Wetlands as stormwater management. Brian Williams. https://www.briangwilliams.us/environment/wetlands-contribution-to-improving-water-quality-and-reducing-storm-water-runoff.html

Image 5. Category 5 hurricane storm surge. Washington Post. https://www.washingtonpost.com/graphics/2017/health/environment/tampa-bay-climate-change/

Image 6, 7, 8. Sea Level Rise Viewer. NOAA. https://coast.noaa.gov/slr/#/layer/slr/10/-9183036.649909183/3236725.549973604/12/satellite/170/0.8/2050/interHigh/midAccretion