Santa Rosa County Resilience to Future Flooding Grant

Water, when it hits the ground, instantly becomes a puddle or rivulet or flood. - Alice Oswald

Santa Rosa County, with an approximate population of 184,313 has 81 miles of rivers and 100 miles of tidally affected shoreline causing a high flood probability with at least one incident of localized flooding annually. As a community that is vulnerable to extreme weather and climate-hazards, it is important for citizens and community leaders to be informed in order to establish a more resilient future.

• In 2014 over 22 inches of water fell in a 29-hour period. This 100-year flood event resulted in unbelievable damage to roads, public buildings, commercial, and residential structures. Hurricane storm surge events, such as those experienced during Hurricane Ivan (2004) and Hurricane Sally (2020) can cause extreme flooding in coastal areas reaching up to 20 feet or more.

Flood zones are geographic areas that the Federal Emergency Management Agency (FEMA) defines according to varying levels of flood risk. These zones are depicted on a community's Flood Insurance Rate Map (FIRM) or Flood Hazard Boundary Map. Flood Zones are defined as the area that will be inundated by the flood event having a 1-percent chance of being equaled or exceeded in any given year. Each zone reflects the potential severity or type of flooding in that area.

For this project, several factors that contribute to flood vulnerability were researched and numerous data sets were collected which fit into four categories: environmental, social, physical/built environmental and economic impacts. With the assistance of a Steering Committee of local subject matter experts, data sets were ranked according to importance when considering flood vulnerability. The three top-ranked variables were: Repetitive Loss Structures, Base Flood Elevation, and Social Vulnerability Index.

A Repetitive Loss Structures (RLS) is any insurable building that has had two or more claims of $1,000 or more paid by the National Flood Insurance Program within any ten-year period since 1978. These areas draw on FEMA funds and are concerning for community leaders and residents as their lives are disrupted and threatened by continual flooding.

FEMA creates Base Flood Elevation (BFE) from historic weather data and topography and uses it as a reasonable standard to insure against. It is defined as the computed elevation of surface water resulting from a flood that has a 1% chance of equaling or exceeding that level in any given year. This identifies the expected height of flood waters in high risk areas.

The Social Vulnerability Index (SVI) is developed by the Center for Disease Control and ranks Census Tracts based on 15 Census variables in 4 categories: Socioeconomic Status, Household Composition and Disability, Minority Status and Language, and Housing Type and Transportation. This data set identifies broad areas containing populations that will most likely need support before, during, and after a disaster event.

Sea level rise storm surge scenarios can be incorporated into the model to help understand the future of climate change impacts on Santa Rosa County. Created as part of the Ecological Effects of Sea Level Rise in the northern Gulf of Mexico, or EESLR-NGOM, project, these storm surge simulation results incorporate waves and surge, land use changes, habitat changes, and shoreline, dune and barrier island morphology. The incorporation of this into the model helps to assess the vulnerability of coastal communities to sea level rise, prepare for the impacts of storm surge with sea level rise, and more effectively assess alternative management strategies for mitigating future ecological and societal impacts of storm surge and sea level rise.

With these three factors chosen, a model was created to identify and score areas of vulnerability. These factors were ranked on a scale from 0-5, with 0 being no risk and 5 being severe risk. Each quarter mile square of the county received scores based on its Social Vulnerability Index, Repetitive Loss Structures, and Base Flood Elevation. These 3 scores were then weighted against one another equally to create an overall vulnerability score for each area. The final vulnerability scores, also ranked 0-5, are an average of the three factors.

Due to the recent weather events caused by Hurricane Sally, an opportunity to validate the vulnerability model arose. Areas of confirmed flood were compared to the areas identified as vulnerable, the results of which verified the accuracy of the model. Further corroboration can be performed by examining information from past flood events, including the 2014 and 2017 floods.

Santa Rosa County will use the vulnerability assessment data and analysis to identify vulnerable areas and develop appropriate plans. From developing an Adaptation Action Plan, to evaluating benefits of nature-based projects in Santa Rosa County, this model provides detailed information staff can use to obtain funds to pursue future projects related to localized flooding.

Existing implementation projects using nature-based solutions to address coastal erosion in Santa Rosa County are at the Floridatown Living Shoreline and the Oyster Shell Recycling Program. Using information gathered by the model, these projects can move forward with new insight of development strategies and engineering solutions.

In the future this model can provide insight into various other areas of interest. The weight of factors can be modified to reflect the target study, providing new information about the relationships between SVI, RLS, and BFE. Moving forward, sea level rise can be included into the model to help identify and protect future vulnerable areas in Santa Rosa County.

Identifying vulnerability is the first step toward building a resilient community. This project will continue to build from the vulnerability assessment using the results to help rank communities within the county most in need of mitigation dollars. A cost estimator was created for a test pilot area of the county as a proof of concept. The application estimates the cost of damages a property may incur due to flooding and provides information on insurance options. Currently the Cost Estimator applicaiton is in BETA format and will be released upon project completion.

Amber Bloechle, University of West Florida

Derek Morgan Ph.D., University of West Florida

Leigh Jeudevine, University of West Florida

Erin Tooher-Thompson, Graduate Research Assistant, University of West Florida

Joy Hazell, University of Florida/ IFAS Extension

Chris Verlinde, University of Florida / IFAS

Shelley Alexander, Santa Rosa County, Florida BOCC

Tanya Gallagher, Ph.D., Santa Rosa County, Florida BOCC

Jessica Paul, GISP, Emerald Coast Regional Council

Tiffany Bates, Emerald Coast Regional Council

Ada Clark, Emerald Coast Regional Council

Renee Collini, Northern Gulf of Mexico Sentinel Site Cooperative

Mikaela Heming, Northern Gulf of Mexico Sentinel Site Cooperative