HomeMy WebLinkAbout2023 03 13 Consent 305 - Approval of the Minutes from the Monday, February 27, 2023 City Commission Regular Minutes • CONSENT AGENDA ITEM 305
,n m=ared CITY COMMISSION AGENDA I MARCH 13, 2023 REGULAR MEETING
1959
TITLE
Approval of the Minutes from the Monday, February 27, 2023 City
Commission Regular Meeting
SUMMARY
RECOMMENDATION
Staff recommends City Commission approve the February 27, 2023 Minutes
as presented.
129
i
CITY COMMISSION
Incorporated REGULAR MEETING MINUTES
1959
M O N ®AY, F E B R VARY 271 2023 AT 6:30 P M
CITY HALL- COMMISSION CHAMBERS
1126 EAST STATE ROAD 434, WINTER SPRINGS, FLORIDA
130
CALL TO ORDER
Mayor Kevin McCann called the Regular Meeting of Monday, February 27,2023 of the City
Commission to order at 6:30 p.m. in the Commission Chambers of the Municipal Building (City Hall,
1126 East State Road 434, Winter Springs, Florida 32708).
Roll Call:
Mayor Kevin McCann, present
Deputy Mayor Rob Elliott, present
Commissioner Matt Benton, present
Commissioner Victoria Colangelo, present
Commissioner Ted Johnson, present
Commissioner Cade Resnick, present
Deputy City Manager Casey Howard, present
City Attorney Anthony A. Garganese, present
City Clerk Christian Gowan, present
Pastor Jeff Dixon led the invocation followed by the Pledge of Allegiance.
Mayor McCann asked if there were any changes to the agenda. Items 303,304,and 309 on the Consent
Agenda were asked to be discussed prior to approval. Mr. Gowan asked that an Item be added after
Item 502 titled Discussion on Operations. There was no objection and the agenda was adopted with
these changes.
AWARDS AND PRESENTATIONS
100. Not Used
INFORMATIONAL AGENDA
200. Not Used
PUBLIC INPUT
Mayor McCann opened Public Input.
Mr. David Florman, 770 East Bahama Road, Winter Springs spoke about the former Mayor, eminent
domain, and other concerns.
Mr. MarkDuplantis, 7590 Wrentham Court, Win ter Springs shared concerns about water trespass from
Southern Oaks and damage to his home.
Ms Karen Meyer, 747 Andover Circle, Winter Springs thought Awards and Presentations should be
presented at 6.30 during the Commission meeting, and spoke about meeting lengths and the start
time.
Ms Christina Higley, Avery Park HOA President spoke about the proposed storage project, potential
impacts on her community, and confusing information. Ms Higley requested that everyone stick to
the facts, help Avery Park compile statistics/facts and poke about attempted communications with
her district commissioner.
Ms Jennifer Sickles, 777 Lakeside Drive, Winter Springs, discussed concerns about possible expired
revitalization of HOA covenants
Mr. Bob Miller, 679 Silvercreek Drive, Winter Springs spoke about a previously discussed petition
regarding Shore Road, the planned restoration of the road, and concerns about speeding and traffic.
CITY COMMISSION MINUTES I REGULAR MEETING I MONDAY, FEBRUARY 27, 2023 1 PAGE 2 OF 10
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Ms. Gina Shafer, Winter Springs Village, Winter Springs spoke about flooding in her community and
noted she was opposed to a new proposed plan regarding Hickory Grove storm water.
Mr.Art Gallo, 799 Nandina Terrace, Winter Springs requested that CALNO bylaws he had read at the
previous meeting be incorporated into the minutes.
Mr. Kevin Cannon, PO Box 795223, Winter Springs spoke about bridge repair efforts, flooding analysis
of upstream impacts that he thought was needed, creek maintenance, and water volume during the
storms
Mayor McCann closed Public Input.
CONSENTAGENDA
300) Surplus Assets
No discussion.
301) FY 2024 Budget Calendar
No discussion.
302) Resolution No.2023-09 Extension#8 of the Declaration of Local Emergency related to Ongoing
Hurricane Ian Recovery
No discussion.
303) Rescission of Bid Award 2022-401
Mr. Philip Hursh, Director, Public Works Department noted the need to rescind the contract due to
outdated prices in the intended piggyback contract.
Attorney Garganese noted the City had previously awarded the contract, unit pricing was escalated,
and some work for Winter Springs was not included in the contract and opined that material
differences required a new competitive bidding process for this project.Attorney Garganese noted an
ITB was to be issued.
Discussion followed on anticipated delays and an updated timeline.
Mr. Hursh explained that he expected an initial three to four week delayto go through the competitive
bidding process, noted contractor scheduling still needed to be determined, and said that, once
started,the project would take three to six months.
304) Shore Road Restoration
Chief Matt Tracht acknowledged speed concerns on Shore Road were valid, commented on speed
control devices previously implemented, and noted more were being ordered.
Discussion followed on communications with residents, the difference between repairing and
rebuilding,the previously mentioned petition from residents, and funding for the repair.
Mr. Hursh confirmed that penny sales tax money would be used and the City would then request
reimbursement through FEMA.
Further discussion about life expectancy of repaired road, and differences between this project and
the Northern Way bridges.
CITY COMMISSION MINUTES I PEGULAR MEETING I MONDAY, FEBRUAPY 27, 2023 1 PAGE 3 OF 10 132
Mr. Hursh noted exposed utilities and other public safety concerns necessitating the repair of Shore
Road.
305) Updates to City Personnel Policy
No discussion.
306) Winter Springs Defined Pension Plan Assumed Rate Of Return Modification
No discussion.
307) AndCo Consulting - Fourth Addendum to Agreement for Investment Performance Monitoring
and Advisory Services
No discussion.
306) Approval of the Minutes from the Monday,January 30,2023 City Commission Special Meeting
No discussion.
309) Approval of the Minutes from the Monday, February l3,2023 City Commission Regular Meeting
Commissioner Johnson asked that the video clip from the February CALNO meeting be included in
the meeting minutes and asked that CALNO bylaws also be entered into the record and included in
the minutes.
"MOTION TO APPROVE CONSENT AGENDA." MOTION BY COMMISSIONER RESNICK. SECONDED BY
DEPUTY MAYOR ELLIOTT. DISCUSSION.
VOTE: BENTON (AYE);COLANGELO(NAY);JOHNSON (AYE); RESNICK(AYE); ELLIOTT(AYE)
MOTION CARRIED 4-1.
PUBLIC HEARINGS AGENDA
400) Second Reading of Ordinance 2023-01 Repealing the Provisions of Chapter 2 Which Provide For
a Set Time of Adjournment for Meetings of the City Commission
Attorney Garganese read Ordinance 2023-01 by title.
Mayor McCann opened Public Hearing for Item 400.
Ms Gina Shafer, Winter Springs Village, Winter Springs notedshe thought meetings should be as long
as necessary to complete the City's business.
Mayor McCann closed Public Hearing for Item 400.
"MOTION TOAPPROVE ORDINANCE 2023-01 AMENDING CHAPTER 2OFTHE CITYOF WINTER SPRINGS
CODE OF ORDINANCES; REPEALING THE PROVISIONS OF CHAPTER 2 WHICH PROVIDE FOR A SET
TIME OFADJOURNMENT FOR MEETINGS OFTHE CITYCOMMISSION;PROVIDING FORTHE REPEALOF
PRIOR INCONSISTENT ORDINANCES AND RESOLUTIONS, INCORPORATION INTO THE CODE,
SEVERABILITY, AND AN EFFECTIVE DATE." MOTION BY COMMISSIONER JOHNSON. SECONDED BY
COMMISSIONER BENTON. DISCUSSION.
VOTE: BENTON (AYE);COLANGELO(NAY);JOHNSON (AYE);RESNICK(NAY);ELLIOTT(AYE)
MOTION CAPRI ED3-2.
CITY COMMISSION MINUTES I REGULAP MEETING I MONDAY, FEBPUAPY 27, 2023 1 PAGE 4 OF 10 133
Discussion followed on preparedness for meetings and consideration of Staff's time.
REGULAR AGENDA
500) Design and Performance of Stormwater Management Systems- Part 3 Briefing
Mr. David Hamstra, Pegasus Engineering, presented Part 3 of a presentation on stormwater design
and standards. Reviewed current Code of Ordinances (Chapter 9) and noted lack of particular criteria
for closed drainage basins. Rate and volume control considerations (9-241 (e)) that are required in the
Code but not enforced with past development - open basin criteria, consistency among Seminole
County and its municipalities.
Mr. Hamstra then discussed five possible higher standards:
(1) Critical Duration Analysis which he noted was currently used by the Florida Department of
Transportation (FDOT);
(2) Unit Peak Discharge;
(3) Hydraulic Monitoring;
(4) Matching Discharge Hydrographs, looking at controlling rate and volume; and
(5) Future Extreme Rainfall.
In regards to the Future Extreme Rainfall, Mr. Hamstra noted a Technical Memorandum from the
South Florida Water Management District (SFWMD) applying a factor-based calculation dependent
on region.
Mr. Hamstra noted implementation of higher standards could discourage future development and
anticipated benefits were not likely to be far reaching given that much of the City was already
developed.
Discussion followed on standards developed by St. Johns River Water Management District
(SJRWMD), potential countywide initiatives and programs, and special basin criteria designations.
Further discussion on retroactive application of higher standards and applicability to redevelopment.
Several Commissioners expressed interest in the special basin criteria as a way to address issues
throughout Seminole County.
Mr. Hamstra noted with regard to special basin criteria that SJRWMD had a lengthy process and had
not approved a special basin in manyyears. Mr. Hamstra thought the process could take two to three
years from start to finish.
Further discussion on current and future development,the location of most current flooding south of
State Road 434, and retrofitting.
Mr. Hamstra then provided an update on the FEMA workshop, noted 16 homeowners were still
interested, and discussed a screening process prior to presenting projects for funding. Mr. Hamstra
also noted that funding for Hurricane Ian had been published and Seminole County was to receive
approximately$20.8 million.
501) Capital Improvement Plan (CIP) - Roadway Resurfacing, Pavement Markings and Calming
Enhancements
Mr. Hursh noted efforts by Staff to rank roads for resurfacing and explained the following roads were
included in the current plan:
CITY COMMISSION MINUTES I PEGULAR MEETING I MONDAY, FEBRUAPY 27, 2023 1 PAGE 5 OF 10 134
Quail Nest Dr. (All)
Sheoah Blvd. (S. Nighthawke Circle to SR 434)
Sheppard Rd. (Sheoah Cir.To Sheoah Cir.)
Hayes Rd. (Silver Creek to 434)
Benchwood Dr. (WSB to Forest Creek)
O'Day Dr. (Trotwood Blvd. to Trotwood Blvd.)
Lamoka Ct. (All)
Oswego Ct. (All)
Olean Ct. (All)
Winter Springs Blvd. (Northern Way to Howell Creek Bridge)
Winter Springs Blvd. (Howell Creek Bridge to City Limits)
Mr. Hursh noted that also included in this was planned installation of speed tables in the area of Sam
Smith Park and the installation of four raised intersections along Winter Springs Boulevard.
Mr. Hursh noted the project budget was $1,896,315.50 to cover resurfacing, striping, and the noted
traffic calming devices. Mr. Hursh explained the money was coming from the Third Generation sales
tax and work would begin within 30 days of approval by the Commission.
Brief discussion followed about possible sidewalk construction in conjunction with the resurfacing.
Mr. Hursh noted that any sidewalk construction would require a separate contractor.
"MOTION TO APPROVE." MOTION BY COMMISSIONER RESNICK. SECONDED BY COMMISSIONER
JOHNSON. DISCUSSION.
VOTE: BENTON (AYE);COLANGELO(AYE);JOHNSON (AYE); RESNICK(AYE); ELLIOTT(AYE)
MOTION CARRIED 5-0.
502) Approval of First Modification to Development Agreement (Mattamy Homes - Hickory Grove
Townhouse Projectl
Mr. Hamstra noted a proposal to direct stormwater from the Hickory Grove project to the City's
Wetland Park rather than a previously approved pond and noted planned outfall improvements to
Wetland Park which would assist with this project and impacts to Michael Blake Boulevard.
Mr. Hursh discussed the planned design.
Discussion followed on the developer's contribution to the project, benefits to Winter Springs Village,
the elimination of the need for pumps, potential berms to mitigate the sheeting of water, efforts to
avoid wetland impacts, and the anticipated timeline.
Mr. Hamstra noted that the goal was to attain permits by late summer and an additional wet season
of pumps would be required. Mr. Hamstra also noted that the berm would be designed to a 100-year
storm event.
Further discussion followed on the partnership between the City and Mattamy Homes, anticipated
ground-breaking, and impacts of construction on water runoff.
Mr. Hamstra explained that construction and silt barriers would be erected, clearing would be
immediately followed by the digging of stormwater ponds, and utilities would be installed. Mr.
Hamstra noted that it was not until impervious surfaces were installed that there could be any issue
but noted that the City hoped to be implementing improvements by that time with the on-site ponds
as additional protection.
CITY COMMISSION MINUTES I PEGULAP MEETING I MONDAY, FEBRUAPY 27, 2023 1 PAGE 6 OF 10
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Mr. Scott Glass, 300 S Orange Avenue, Orlando noted a provision in the modification precluding
Mattamy Homes from discharging at certain times and explained the project could be temporarily
shut down if this provision was violated.
Mayor McCann asked about ownership of a parcel adjacent to the Wetland Park and if it were subject
to development.
"MOTION TO APPROVE." MOTION BY COMMISSIONER RESNICK. SECONDED BY DEPUTY MAYOR
ELLIOTT. DISCUSSION.
VOTE: BENTON (AYE);COLANGELO(AYE);JOHNSON (AYE); RESNICK(AYE); ELLIOTT(AYE)
MOTION CARRIED 5-0.
502a) Discussion on Operations
Mr. Gowan read a statement provided by City Manager Shawn Boyle noting his intent to retire from
the City of Winter Springs.
"I MAKE A MOTION THAT EFFECTIVE IMMEDIATELY WE RELEASE SHAWN BOYLE FROM HIS
OBLIGATIONS AS CITY MANAGER OF THE CITY OF WINTER SPRINGS AND DIRECT STAFF TO BRING AN
AGENDA ITEM FORWARD FOR RECRUITING OF A NEW CITY MANAGER." MOTION BY DEPUTY MAYOR
ELLIOTT.SECONDED BY COMMISSIONER JOHNSON. DISCUSSION.
Mayor McCann opened Public Input
Mr.Art Gallo, 799 Nandina Terrrace, Winter Springs commented on the pressure associated with the
job, thought Mr. Boyle was a great City Manager and it would be tough to fill his shoes.
Mr. Bob Miller, 679 Silvercreek Drive, Winter Springs noted his previous experience on the dais,
planned audits, comments on the political environment in the City, and urged everyone to work
together.
Ms Gina Shafer, Winter Springs Village, Winter Springs noted she thought Mr. Boyle was a great
working manager and a great man. Wished him the best. Commented on the political environment
in the City.
Ms Donna Bruno,599Alton Road, Winter Springs noted she wassaddened to hear the news, her work
with him for manyyears, and commented on his commitment to the City.
Ms Sheila Benton, 474 Cedarwood Court, Winter Springs quoted Thomas Jefferson, noted Mr. Boyle's
work in the City and thought he was treated unfairly.
Mr. Kevin Cannon, PO Box 795223, Winter Springs noted he thought development/developers were
the issue. Noted staffing issues as a result of the political environment in the City.
Mayor McCann closed Public Input.
VOTE: BENTON (AYE);COLANGELO(AYE);JOHNSON (AYE); RESNICK(AYE); ELLIOTT(AYE)
MOTION CARRIED 5-0.
"I MAKE A MOTION TO APPOINT PHIL HURSH AS INTERIM CITY MANAGER SUBJECT TO CONTRACT
NEGOTIATIONS WITH CITY ATTORNEY GARGANESE AND DIRECTION TO BEGIN A NATIONAL SEARCH
CITY COMMISSION MINUTES I REGULAP MEETING I MONDAY, FEBPUARY 27, 2023 1 PAGE 7 OF 10
136
FOR A FULL TIME CITY MANAGER." MOTION BY DEPUTY MAYOR ELLIOTT. SECONDED BY
COMMISSION ER JOHNSON. DISCUSSION.
Mayor McCann opened Public Input.
Mr. William Morissey, 965 Sequoia Drive, Winter Springs thought Mr. Hursh was the best man for the
job.
Mr. Art Gallo, 799 Nandina Terrace, Winter Springs thought Mr. Hursh was a good choice and would
need a lot of help, hoped he wouldn't be subject to the same attacks.
Mr. Kevin Cannon, PO Box 795223, Winter Springs noted he thought Mr. Hursh was the logical choice,
the City Manager position could not remain vacant, and thought the search could take a while and
needed to start as soon as possible.
Ms Gina Shafer, Winter Springs Village, Winter Springs thought Mr. Hursh was a good choice and the
City needed a City Manager immediately.
Mayor McCann closed Public Input.
Discussion followed on if an Interim City Manager was needed immediately, the desire to make an
informed decision,and if the Deputy City Manager could take on some of the duties. Deputy Manager
Howard noted she was not interested in serving in the Interim role.
Attorney Garganese noted the City Charter required a City Manager to act as administrative officer,
that there needed to be someone in the role whether interim or otherwise. Continuing, Attorney
Garganese noted the Deputy City Manager would have to consent to taking on additional duties.
Attorney Garganese noted that in terms of moving forward, the Commission could look internally or
externally to appoint someone on an interim basis,short-term or long-term dependent on the will of
the Commission.
Deputy Mayor Elliott noted he made a motion to appoint Mr. Hursh because of his experience as
Public Works Director and the ongoing projects at the Wastewater plants.
Further discussion followed on the need for someone to immediately take on the role of Manager in
the interim and the potentially lengthy process of advertising and selecting a new permanent
manager.
Mr. Hursh noted he was willing to serve on an interim basis.
VOTE: BENTON (AYE);COLANGELO(AYE);JOHNSON (AYE); RESNICK(AYE); ELLIOTT(AYE)
MOTION CARRIED 5-0.
"MOTION TO REMOVE THE PREVIOUS AUTHORIZED REPRESENTATIVES FOR BANKING AND
CHECKING ACCOUNTS - DEPUTY CITY MANAGER CASEY HOWARD, CITY MANAGER SHAWN BOYLE,
AND FORMER FINANCE DIRECTOR SCOTT BORROR - AND REPLACE THEM WITH INTERIM CITY
MANAGER PHIL HURSH AND INTERIM DIRECTOR OF FINANCE DONNA BRUNO. ALSO TO HAVE
ANTHONY PREPARE RESOLUTIONS TO REFLECT THIS CHANGE DESIGNATING PHIL AND DONNA AS
AUTHORIZED REPRESENTATIVES TO EXECUTE DOCUMENTATION WITH FIFTH-THIRD AND REGIONS
BANKS." MOTION BY DEPUTY MAYOR ELLIOTT. SECONDED BY COMMISSIONER JOHNSON.
DISCUSSION.
Brief discussion about required number of authorized representatives.
CITY COMMISSION MINUTES I REGULAP MEETING I MONDAY, FEBPUAPY 27, 2023 1 PAGE 8 OF 10
137
VOTE: BENTON (AYE);COLANGELO(AYE);JOHNSON (AYE); RESNICK(AYE); ELLIOTT(AYE)
MOTION CARRIED 5-0.
503) Appointment Opportunities for City Boards and Committees
No appointments were made.
504) New Business
Commissioner Johnson asked about speed limits within Tuscawilla and noted he thought Winter
Springs Boulevard should be reduced to 25 miles per hour to be consistent. Commissioner Johnson
asked that a discussion on this topic be placed on a future agenda.
Commissioner Colangelo noted discussions about a Florida Department of Environmental Protection
grant she had with Mr. Boyle and asked Mr. Hursh to look into this.
Commissioner Resnick asked that the Moss Park area be looked at for median revitalization.
REPORTS
600) Interim City Manager Phil Hursh
• Noted that he had received confirmation from FDOT that the speed limit along State Road 434
throughout the City was being reduced to 45 miles per hour.
601) City Attorney Anthony A.Garganese
No report
602)City Clerk Christian Gowan
No report
603) Mayor Kevin McCann
• Noted attendance at opening day of Babe Ruth baseball which was celebrating 30 years;
• Noted Winter Springs High School had won the state weightlifting championship.
604) Seat One Commissioner Matt Benton
No report
605) Seat Two Commissioner Victoria Colangelo
• Noted her continued communication with constituents and her maintenance of a
spreadsheet related to every resident she has spoken with.
606) Seat Three Commissioner Ted Johnson
No report
607) Seat Four Commissioner Cade Resnick
• Noted that water was the main issue he was concerned with and that he was not pro-
development;
• Asked that the Commission get to know each other as a team and work cooperatively.
CITY COMMISSION MINUTES I PEGULAR MEETING I MONDAY, FEBRUAPY 27, 2023 1 PAGE 9 OF 10
138
608) Seat Five Commissioner/Deputy Mayor Rob Elliott
• Noted his attendance at Babe Ruth;
• Noted his attendance at the Avery Park HOA meeting attendance and good discussion he had
with Seminole County Commissioner Bob Dallari.
PUBLIC INPUT
Mayor McCann opened Public Input.
Ms Gina Shafer noted her attendance at the Parks and Recreation Advisory Committee meeting,
encouraged Commissioners to attend a meeting, and noted she thought a mother/son dance or
event would be nice. Ms Shafer also asked about changes to sandbag distribution and placing
Hometown Heroes banners throughout the City.
Mr. Art Gallo, 799 Nandina Terrace, Winter Springs noted proposed agenda items for the CALNO
meeting including the Seminole County Public School Interlocal Agreement and stormwater
planning.
Mr. Kevin Cannon, PO Box 795223, Winter Springs spoke about concerns related to development
within the City and the actions of some Commissioners
Mayor McCann closed Public Input.
ADJOURNMENT
Mayor McCann adjourned the meeting at 9:53 P.M.
RESPECTFULLY SUBMITTED:
CHRISTIAN D. GOWAN, MPA
CITY CLERK
APPROVED:
MAYOR KEVIN McCANN
NOTE: These Minutes were approved at the 2023 City Commission Regular Meeting.
CITY COMMISSION MINUTES I PEGULAP MEETING I MONDAY, FEBPUARY 27, 2023 1 PAGE 10 OF 10 139
The following comments were
read and entered into the record
by Ms. Christina Higley,
President, Avery Park
Homeowners Association during
the First Public Input on
February 27, 2023
140
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Good Evening. My name is Christina Higley and I am a resident as well as the
President of the Avery Park Homeowners Association.
As many know, the storage unit project across from our community is weighing
heavily on the minds of our residents. This project could have not only
ramifications for our neighborhood, but the City of Winter Springs long term as
well. This has left communities like Avery Park scrambling and with a lot of
unanswered questions. I have spent time bouncing between the city and county
doing as much fact finding as possible and I have received as I'm sure you won't
be surprised to hear a lot of conflicting information.
It is evident between conversations with the city as well as the county that there
are a lot of politics and egos involved. I am disappointed to see what is
transpiring and it has left residents like myself needing to decipher what is true or
simply untrue while trying to get together the pertinent information needed to
push back on this monstrosity. Sadly, it does not feel like many involved have the
residents who will be most negatively impacted best interests in mind.
I do want to acknowledge before moving forward our community is grateful for
Commissioner Elliot as well as Mayor McCann's time after they came to our last
board of directors meeting. We still have a lot of questions and do have a request
this evening after further evaluating the information shared. We are asking that
we try and put all emotions aside and let's stick to the facts. The county wants the
facts, not our emotions when they ultimately vote on rezoning this property and
approving the project. PLEASE help the citizens of Avery Park and surrounding
communities prepare those facts. Whether it is crime statistics, environmental
concerns, previously denied applications for the property allegedly 5 years ago,
we need your help at the city fact finding and preparing our case. As we all know,
being a HOA board member at times can be a very thankless job and is 100%
volunteer. We operate on very tight budgets and have our own problems behind
our gates. Folks like myself NEED your help to make sure we can deliver a
powerful and very well executed message to the county when our time comes.
1
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T
Please promise to continue to partner with us at Avery Park and provide just the
facts.
To Commissioner Colangelo who represents our district, many in our community
are surprised we have not heard from you and it definitely has many wondering
what you are doing to keep this detrimental development out of our city.
I emailed you on behalf of Avery Park on January 4th asking where you stand with
the project. On January 5th, you emailed me back and I quote "I am highly against
having a storage unit by a Elementary/Middle School. We are currently working
with Seminole County to annex the property into Winter Springs." You also stated
and I quote, "the next step is for Winter Springs to obtain ownership of this land
and refuse the approval of a storage facility."
Fast forward to a few short weeks later and the doom and gloom email hit our
inboxes first week of February, pointing fingers and throwing in the towel to
never hear from you again. To quote this email and article sent by Victoria
Colangelo for Winter Springs (which I believe has since been edited):
"So there you have it. We'll have no opportunity to vote on this development
because the city didn't have the foresight to see this coming down the road."
Okay, well that's great, but how does that help your constituents now? How does
this help solve the massive problem we are facing at Avery Park? How do you
plan on being a part of the solution?
Commissioner Colangelo, like tens of thousands of others in our country, I moved
19 months ago over 1100 miles from the only state I had ever lived in up north to
give our children a better life. I left a community full of toxic politics where
deflection, finger pointing, and the blame games slowly destroyed our city and
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state. A community where "Leaders" got very little done to actually protect and
help those in their communities. Rather they were a bunch of self-serving
individuals with agendas that sold out their constituents deal by deal in the
darkness and left our once clean and beautiful cities like Winter Springs
unrecognizable to poorly planned big development projects like this storage unit
that inevitably brought the crime and rift raft that came along with it. Tonight I
am sounding the alarm...) refuse to be so ignorant or fall victim to these games
again in my new city.
To each of you sitting here tonight, you may not ultimately have a final vote at the
county level, but you do have an obligation as elected officials and city employees
to stand by the residents you serve and help in any way possible. I don't care
what people did in the past. Election season and the fear mongering and finger
pointing is over. It's time to get to work. What citizens care about is what each of
you plan to do now to help right those wrongs and save our city from becoming
where I moved from. I am asking each of you including you Commissioner
Colangelo this evening to get a hold of the local HOA boards—such as Tuskawilla
Crossings and Avery Park and let us know how you plan on helping our
community's push back on this project and be a part of the solution. That is if you
are truly against this proposed facility that will change the landscape of our city
forever.
Thank you for your time.
3
The following document was
referenced by Mr. David Hamstra
during the discussion of Item
500 and entered into the record .
144
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Technical Memorandum:
ADOPTION OF FUTURE EXTREME RAINFALL CHANGE FACTORS
FOR FLOOD RESILIENCY PLANNING IN SOUTH FLORIDA
April 27, 2022
Page intentionally left blank.
146
ACKNOWLEDGMENTS
This technical memorandum was made possible by the guidance, support,and contributions of a dedicated
team of individuals at the South Florida Water Management District,United States Geological Survey,and
United States Army Corps of Engineers. We would like to especially acknowledge the technical feedback
provided by the United States Geological Survey Caribbean—Florida Water Science Center and Florida
International University Sea Level Solutions Center, and express our appreciation to the Future Extreme
Rainfall Projections Technical Workgroup members who assisted with the preparation of this memorandum
as follows:
PROJECT TEAM
South Florida Water Management District
Carolina Maran District Resiliency
Nicole Cortez District Resiliency
Francisco Pena District Resiliency
Walter Wilcox Hydrology and Hydraulics Modeling
Jenifer Barnes Hydrology and Hydraulics Modeling
Hongying Zhao Hydrology and Hydraulics
Akin Owosina Hydrology and Hydraulics
Karin Smith Water Supply Planning
Kristopher Esterson Water Supply Planning
Sean Sculley Applied Sciences
Brian Turcotte Applied Sciences
Todd Kimberlain Meteorological Operations
United States Army Corps of Engineers
Ceyda Polatel Jacksonville District
Drew Coman Jacksonville District
Matt Fischer Jacksonville District
147
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148
EXECUTIVE SUMMARY
Extreme rainfall occurrences are being documented throughout South Florida, along with the examination
of flooding impacts resulting from these events. The South Florida Water Management District(SFWMD
or District) published initial trend analyses to assess how these observed events have been changing in
terms of frequency and magnitude in South Florida in the 2022 South Florida Environmental Report.
Research conducted at Florida International University (FIU) has evaluated how these extreme rainfall
occurrences will happen under future conditions and demonstrated limitations in terms of how available
global climate model datasets reproduce rainfall occurrence in Florida(FIU 2019). With higher certainty
that temperatures will continue to increase over the coming decades, as documented in the
Intergovernmental Panel on Climate Change(IPCC) Sixth Assessment Report(IPCC 2022),it is important
that resultant changes in rainfall be properly assessed.The need for estimating future extreme rainfall events
for planning purposes is recognized by water managers and stakeholders in South Florida, as the water
management system has limited flexibility to accommodate extreme variations in rainfall volumes and
continue to provide the desired level of flood protection. Quantifying the occurrence of such events is
critical to support resiliency planning efforts, by properly accounting for rainfall driven flooding risks, in
addition to sea level rise driven flooding risks,in local and regional flood vulnerability assessments.
As a key part of its resiliency strategy,the SFWMD evaluates the status of its flood control infrastructure
and advances adaptation strategies necessary to continue providing flood protection for South Florida under
current and future climate conditions.Future extreme rainfall projections are relevant inputs,as well as sea
level rise scenarios, that are being incorporated into the Flood Protection Level of Service (FPLOS)
program's integrated stormwater hydrology and hydraulics models, to enhance resiliency planning and
more comprehensively evaluate compound flooding impacts.
To support the delineation and selection of such future extreme rainfall scenarios,the SFWMD entered into
a cooperative agreement with the United States Geological Survey (USGS) Caribbean—Florida Water
Science Center and the FIU Sea Level Solutions Center to develop future depth-duration-frequency(DDF)
curves based on available global climate model downscaled datasets. This technical memorandum
delineates the SFWMD's adoption of future extreme rainfall change factors (scenario formulation)as part
of its flood resiliency planning efforts, based on the preliminary results published in a data release by
Irizarry-Ortiz and Stamm (2022). A final report of the USGS component of this project is expected to be
published in 2022.This USGS future conditions study,which is centered around the year 2070, is intended
to support the advancement of District resiliency initiatives with the consideration of future extreme rainfall
occurrences by setting the foundation to improve planning standards for flood vulnerability assessments.
Change factors represent the calculated ratio of modeled future rainfall depths to historic rainfall depths for
a given rainfall event, and are applied to multiply the equivalent National Oceanic and Atmospheric
Administration (NOAA Atlas 14)precipitation frequency estimates to determine increasing or decreasing
future rainfall. Change factors greater than 1.0 (one) represent future rainfall increase, and less than 1.0
(one) represent rainfall decrease for a given event. The criteria for results selection and initial scenario
formulation were based on technical consensus upon the evaluation of the available results and the best
approach to represent associated uncertainty. This technical memorandum presents computed change
factors, as summarized in Figure ES-1,based on the 50% confidence interval of the model spread for 1-,
3-,and 7-day duration and 5-, 10-,25-,50-, 100-,and 200-year return frequency events using the ensemble
of all model results for both medium-low and high future emissions scenarios compiled by 16 counties and
14 rainfall areas within the SFWMD boundaries as well as the Everglades National Park rainfall area, and
an additional combined rainfall area for the Florida Keys and Biscayne Bay.
ES-1
149
Future Rainfall Change Factors Future Rainfall Change Factors
25-yr 1-day Duration-Median and 50%Confidence Interval 100-yr 3-day Duration-Median and 50%Confidence Interval
St.Lucie County St.Lucie County
Polk County Polk County
Palm Beach County Palm Beach County
Osceola County Osceola County
Orange County Orange County
Okeechobee County Okeechobee County
Monroe County Monroe County
Miami-Dade County Miami-Dade County
Martin County Martin County
Lee County Lee County
Highlands County Highlands County
Hendry County Hendry County
Glades County Glades County
Collier County Collier County
Charlotte County Charlotte County
Broward County Broward County
0.9 1.1 1.3 1.5 0.9 1.1 1.3 1.5 1.7
Figure ES-1. Future rainfall change factors for counties(median and 50%confidence interval,25-year/1-day
and 100-year/3-day duration).
With the goal of facilitating data accessibility, advancement of common practices, comparison of
evaluations, and regional consistency,the results are also made available through the SFWMD Resilience
Metrics Hub's Future Extreme Rainfall Change Factors for Flood Resiliency Planning in South Florida
Web Ann. The entire set of results for each global climate model dataset and additional percentile ranges
are available at the USGS ScienceBase data release portal: https:Hdoi.org/l0.5066/P935WRTG.
An example of how to perform flood vulnerability analyses considering future extreme rainfall scenarios is
also summarized in this technical memorandum.A set of future rainfall change factors extreme rainfall
scenarios based on selected threshold values within the results' confidence interval was applied to the
C-8 and C-9 basins in Miami-Dade and Broward counties, utilizing the FPLOS models (for the 3-day
duration, 100-year recurrence event). The sensitivity test results illustrate increasing flood risks in these
basins,represented by up to a 1-ft increase in overland flow inundation resulting from these selected future
rainfall scenarios.
The next steps in assessing future rainfall and reducing relative uncertainty in climate model projections
include the development of statewide regional climate models and efforts to continue to document observed
trends in water and climate related metrics, and other sources of information that impact rainfall into the
future. While these refinements are being completed, the proposed future extreme rainfall change factors
summarized in this technical memorandum are encouraged to be adopted in the interim to account for
changing future extreme rainfall conditions and to properly estimate compound flood risks from coastal
and inland flooding hazards, as part of flood vulnerability assessments and other regional and local
resiliency planning efforts,along with incorporation of methods for decision making under uncertainty and
flexible planning approaches.
ES-2
150
STATEMENT OF USE
This technical memorandum provides initial guidance and example application to aid planning practices on
how to apply estimated change factors to account for future extreme rainfall events as part of local and
regional flood vulnerability assessments. The data provided herein are considered applicable within the
SFWMD boundaries and should be rigouroulsy interpreted in the context of each particular application.
Users are fully responsible for the application of the data. The results, and associated recommendations
included in this memorandum, are not providing the necessary level of resolution that would be applicable
to advance modernization of design criteria or to inform regulatory programs; therefore, these are not
included as part of a District's mandate. Change factors were computed from 40-year periods representing
future projected climate for the period 2050-2089 (centered in 2070) and historical (retrospective)
conditions for 1966-2005 and might be derived to represent planning scenarios within SFWMD
boundaries. This technical memorandum is provisional pending the publication of the final report to be
published by the USGS.
PREFERRED CITATION
SFWMD. 2022. Technical Memorandum:Adoption of Future Extreme Rainfall Change Factors for Flood
Resiliency Planning in South Florida. South Florida Water Management District,West Palm Beach,FL.
DATA SOURCE
Irizarry-Ortiz, M.M. and J.F. Stamm. 2022. Change Factors to Derive Future Precipitation Depth-
Duration-Frequency (DDF) Curves at 174 National Oceanic and Atmospheric Administration (NO-4A)
Atlas 14 Stations in Central and South Florida. United States Geological Survey Data Release. Available
online at hiips://doi.org/l 0.5066/P935WRTG as of April 2022.
i
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TABLE OF CONTENTS
Introduction...................................................................................................................................................I
Datasetsand Methodology............................................................................................................................2
AvailableResults..........................................................................................................................................3
OverallObservations and Findings...............................................................................................................9
OverallRecommendations.......................................................................................................................... 10
Example Application of Rainfall Change Factors...................................................................................... 16
Conclusions.................................................................................................................................................21
LiteratureCited...........................................................................................................................................23
Appendix A: Table of Computed Change Factors for Counties in the SFWMD Boundaries................A-1
Appendix B: Graphs of Computed Change Factors for the Counties within SFWMD Boundaries.......B-1
Appendix C: Table of Computed Change Factors for SFWMD Rainfall Areas....................................C-1
Appendix D: Graphs of Computed Change Factors for SFWMD Rainfall Areas..................................D-1
Appendix E: Sensitivity Analysis Applying Rainfall Change Factors at C-8 and C-9 Basins..............E-1
ii
153
LIST OF TABLES
Table 1. Computed median change factors for counties..................................................................... I I
Table 2. Computed median change factors for rainfall areas. ............................................................ 14
Table 3. Relationship between rainfall change factors and increased flood depths for the C-8
profile, C-9 profile, and across both basins combined.......................................................... 16
LIST OF FIGURES
Figure 1. Change factor definition from the multiplicative quantile delta method (Adapted from
Irizarry et al. 2016, and as established by Yin et al. 2019).....................................................3
Figure 2. Change factor spread for all models,with outliers,for Climate Region 4...............................4
Figure 3. Change factor spread for all models,with outliers,for Climate Region 5...............................5
Figure 4. Change factor spread for best models,with outliers, for Climate Region 4.............................6
Figure 5. Change factor spread for best models,with outliers, for Climate Region 5.............................7
Figure 6. Change factor results for Palm Beach County—showing spread among stations within the
rainfallarea. .........................................................................................................................8
Figure 7. Map of computed change factors for the 16 counties within the SFWMD boundaries for
the 3-day duration and 100-year return frequency, based on the 50% confidence interval
(within the 25th and 75th percentile) for the ensemble of all model results and combined
emissions scenarios (RCP 4.5 and RCP 8.5)........................................................................ 13
Figure 8. Map of computed change factors for the 14 rainfall areas within the SFWMD boundaries,
as well as Everglades National Park, and a combined Florida Keys and Biscayne Bay
rainfall area, for the 3-day duration and 100-year return frequency, based on the 50%
confidence interval(within the 25th and 75th percentile of models spread)for the ensemble
of all model results and combined emissions scenarios(RCP 4.5 and RCP 8.5)................... 15
Figure 9. C-9 Canal peak stage profiles for 100-year 72-hour design storm using four rainfall change
factors(75%, 50%,40%,and 30%)that are paired with SLR scenarios(CC, SLRI,SLR2,
and SLR3). The RMSD (lower left) values illustrate the similarities (green) and
differences (yellow) between water surface elevation profiles using different
combinations of rainfall change factors and SLR scenarios. Results show that CC 75%,
SLRI 50%, SLR2 40%, and SLR3 30% scenarios produce consistent water surface
elevations on the "inland" canal profile (red horizontal line), from upstream to Interstate
95....................................................................................................................................... 17
Figure 10. Flood inundation map for 100-year 72-hour design storm event for SLR3 scenario with a
20%rainfall change factor.................................................................................................. 18
Figure 11. Flood inundation map for 100-year 72-hour design storm event for SLR3 scenario with a
75%rainfall change factor.................................................................................................. 19
Figure 12. Maximum flood inundation depths (0 to > 2.25 feet) of four different scenario
combinations (CC + 75%, SLRI + 50%, SLR2 + 40%, and SLR3 + 30%) and rainfall
change factors in the C-8 (gray dashed line) and C-9 (magenta dashed line) basins. The
transition zone (red circle)is highly vulnerable to the combined impacts of multiple flood
drivers (rainfall, river discharge, tides, and water table) as a result of its low-elevation
coastal zone, shallow water table, and complex hydrogeology. Flood maps illustrate that
flood inundation depths are more similar"inland" compared to the coastal portion of the
domain,which is exacerbated by the impact of SLR...........................................................20
in
154
ACRONYMS AND ABBREVIATIONS
CC current conditions
DDF depth-duration-frequency
District South Florida Water Management District
FIU Florida International University
ft foot
IPCC Intergovernmental Panel on Climate Change
NOAA National Oceanic and Atmospheric Administration
PM performance metrics
RCP Representative Concentration Pathway
RMSD root mean square difference
SFWMD South Florida Water Management District
SLR sea level rise
USACE United States Army Corps of Engineers
USGS United States Geological Survey
iv
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156
INTRODUCTION
This technical memorandum delineates the South Florida Water Management District's (SFWMD or
District) adoption of future extreme rainfall change factors as part of its flood resiliency planning efforts.
Change factors represent the calculated ratio of modeled future rainfall depths to historic rainfall depths for
a given rainfall event, and are applied to multiply the equivalent National Oceanic and Atmospheric
Administration(NOAA Atlas 14)precipitation frequency estimates to determine future rainfall(Figure 1).
The United States Geological Survey (USGS) Caribbean—Florida Water Science Center and the Florida
International University (FIU) Sea Level Solutions Center have entered into cooperative agreements with
the SFWMD to estimate extreme rainfall and develop future depth-duration-frequency (DDF) curves for
areas within the SFWMD boundaries as well as the Everglades National Park rainfall area,and an additional
combined rainfall area for the Florida Keys and Biscayne Bay.This technical memorandum is based on the
preliminary results published in a data release by Irizarry-Ortiz and Stamm (2022). A final report of the
USGS component of this project is planned to be published in 2022. The USGS future conditions study,
which is centered around the year 2070, is intended to support the advancement of District resiliency
initiatives with the consideration of future extreme rainfall occurrences by setting the foundation to improve
planning standards for flood vulnerability assessments.The current results,as summarized in this technical
memorandum, do not include average future rainfall projections, shifts in seasonality, or an assessment of
drought occurrences(extreme dry)in the future.
The purpose of this technical memorandum is to summarize technical recommendations supporting the
adoption of future extreme rainfall scenarios for ongoing resiliency planning efforts at the SFWMD and to
provide an overview of the analyses performed by the USGS, FIU, and SFWMD to estimate future
conditions extreme rainfall depths and generate DDF curves.Future conditions rainfall scenarios are being
incorporated into the SFWMD's Flood Protection Level of Service (FPLOS)program's flood vulnerability
assessments and other regional and local hydrological/hydraulic model simulations that estimate flood risks
driven by future extreme rainfall conditions. Under the FPLOS program, the SFWMD studies the canals,
structures, and pump stations it operates to ensure these facilities can provide the level of flood protection
they were designed for while considering future conditions like sea level rise and other climate change
impacts.The FPLOS program advances integrated modeling efforts in priority basins to assess potential for
flooding and identify flood adaptation solutions to ensure that each basin can maintain its designated flood
protection level of service.
These ongoing resiliency planning efforts and vulnerability assessments already account for future land use
changes, population increase, the effects of projected sea level rise, and groundwater table changes to
predict future flood conditions.By integrating projected rainfall changes,these advanced assessments will
serve as the basis for more comprehensive flood adaptation planning efforts and more robust prioritization
of resiliency infrastructure investments with consideration of the full range of compound flooding factors.
Additionally, the results summarized in this technical memorandum address recommendations from the
Workshop Report and Strategy Document: Development of Unified Rainfall Scenarios for Florida,
sponsored by the SFWMD and organized by FIU(FIU 2019).Participating experts and stakeholders jointly
evaluated the existing global climate modeling approaches and available downscaled datasets for estimating
future rainfall, and recommended the following:
(1) The SFWMD should complete evaluation of candidate climate-downscaled datasets available for
short-tern planning and develop an ensemble of realizations that may be used as scenario input to
hydrologic/hydraulic/hydrodynamic models. The use of the "Stress Testing" approach should be
fully explored to identify a subset/ensemble of downscaled datasets that are relevant to resiliency
planning objectives.
1
157
(2) As a longer-term effort,the SFWMD, in collaboration with other water management districts and
partners, should support the development of a statewide regional climate model at a resolution
capable of capturing local climate driven processes, such as the occurrence of convective rainfall,
which have a large influence on rainfall patterns in the Florida peninsula.
While a higher resolution statewide regional climate model is being developed as part of a longer term
initiative to reduce downscaled uncertainty,the adoption of presented future extreme rainfall change factors
developed through the SFWMD/USGS/FIU partnership and summarized in this technical memorandum is
encouraged as part of flood resiliency planning efforts. With the goal of facilitating data accessibility to
partner agencies and to the public, advancement of common practices, comparison of evaluations and
regional consistency,the results are made available through the SFWMD Resilience Metrics Hub's Future
Extreme Rainfall Change Factors for Flood Resiliency Planning in South Florida Web App.
DATASETS AND METHODOLOGY
Downscaled climate datasets derived from available global climate general circulation models were
evaluated, as part of the SFWMD/USGS/FIU partnership, to estimate future extreme rainfall centered
around 2070, for the medium-low (RCP 4.5) and high (RCP 8.5) emission scenarios. Representative
Concentration Pathways, or RCPs, are simulated scenarios of future concentrations of greenhouse gas in
the atmosphere. These emissions scenarios are incorporated into global climate models to account for
factors that alter the earth's climate system when projecting future climate change impacts,such as rainfall.
Four downscaled climate datasets were evaluated: (1)the Coordinated Regional Downscaled Experiment
(CORDEX) dataset, (2) the Localized Constructed Analogues (LOCA) dataset, (3) the Multivariate
Adaptive Constructed Analogs (MALA) dataset, and (4) the Analog Resampling and Statistical Scaling
Method by Jupiter Intelligence using the Weather Research and Forecasting Model(JupiterWRF).
Historical DDF curves were derived by NOAA at meteorological stations in Central and South Florida
based on annual maxima and partial-duration series approaches and published in NOAA Atlas 14 (Perica
et al. 2013). These historical DDF curves are to be multiplied by estimated change factors (Figure 1) to
determine future extreme precipitation depths for events of a given duration and return period. Change
factors greater than 1.0 (one) represent future rainfall increase, and less than 1.0 (one) represent rainfall
decrease. For example, a change factor equal to 1.3 represents a rainfall increase of 30%. Change factors
were determined for durations of 1, 3, and 7 days, and return periods of 5, 10, 25, 50, 100, and 200 years.
Change factors were computed from 40-year periods representing future projected climate for the period
2050-2089(centered in 2070) and historical(retrospective)conditions for 1966-2005.
More details about the methodology will be included in the upcoming USGS publication, final delivery
product of the SFWMD/USGS Cooperative Agreement, currently under final peer-review. The
accompanying data release is available on the USGS ScienceBase site via the citation:Irizarry-Ortiz,M.M.
and J.F. Stamm. 2022. Change Factors to Derive Future Precipitation Depth-Duration-Frequency (DDF)
Curves at 174 National Oceanic and Atmospheric Administration(NO, A)Atlas 14 Stations in Central and
South Florida. United States Geological Survey Data Release. Available online at
htt2s:Hdoi.org/10.5066/P935WRTG as of April 2022.
2
158
0
` Change Factor Definition from the
c-0.8 Multiplicative Quantile Delta Method
I =F-1 a-c(G)* {F-1 m-p(G)/F-1 m-c(G))
It
'A CF
a I I F-1a-c(G)=Historic Observed Rainfall Term
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— Fx
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Figure 1. Change factor definition from the multiplicative quantile delta method(Adapted from Irizarry et al.
2016,and as established by Yin et al.2019).
AVAILABLE RESULTS
The USGS data release product referenced above (https:Hdoi.org/10.5066/P935WRTG) contains the
calculated median change factors(50t1i percentile)for precipitation depths at different durations and return
frequency,and respective model spread(5"', 16'h, 50th, 84'11, and 95'h percentiles).A more detailed analyses
of these results,compiled for all the models included as part of CORDEX,LOCA,MACA,and JupiterWRF
downscaled datasets,are included in the upcoming USGS final publication referenced above.It is important
to note that the SFWMD boundaries encompass two climate regions(Climate Region 4—Central and South
Florida,and Climate Region 5—South Florida);therefore,the analyses were completed for the entire extent
of these two regions,stretching as far east to the St.Lucie Estuary and west to the Caloosahatchee Estuary,
respectively. Analyses of these available data release results by the Future Extreme Rainfall Projections
Technical Workgroup(named in the Project Team section of this report)found that the change factors vary
as follows: by RCP 4.5 and RCP 8.5 emission scenarios, by different datasets, by different models with
each dataset,by considering a subset of best models,by individual rainfall stations,and by different regions.
The subset of best models was compiled based on a novel culling methodology technique developed to
identify downscaled climate models that better represent observed historical patterns of precipitation
extremes(Irizarry-Ortiz and Stamm 2022). Figures 2 to 6 illustrate the overall model results(median and
model spread,including outliers)for all models in Climate Regions 4 and 5(Figures 2 and 3),for a selected
subset of selected best models in Climate Regions 4 and 5(Figures 4 and 5),and for a selected rainfall area
and respective stations within it(Figure 6). These figures were generated by the Future Extreme Rainfall
Projections Technical Workgroup based on data provided in the USGS data release (Irizarry-Ortiz and
Stamm 2022), and the respective values are listed in the appendices.
As observed in these figures,there is a noticeable wide spread of the derived change factors,representing
variation between models, datasets, climate regions, and rainfall stations within a representative rainfall
area. The spread represents both uncertainty from overall global climate modeling, emission scenario
formulation, and downscaling approaches, as well as natural variability that pertains to rainfall occurrence
in Florida; such uncertainty will remain even with the incorporation of higher resolution climate model
results. Overall observations and findings are summarized in the sections below, along with initial
recommendations for planning scenario formulation.
3
159
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OVERALL OBSERVATIONS AND FINDINGS
The data provided in the USGS data release (Irizarry-Ortiz and Stamm 2022) were evaluated by experts
from the Future Extreme Rainfall Projections Technical Workgroup to provide an initial interpretation of
the available results, assessing their significance as part of flood vulnerability studies, and describing
overall observations and findings that could be used to facilitate their application as part of regional and
local resiliency planning efforts. These overall observations and findings are summarized below:
• FUTURE EXTREME RAINFALL: Median results from a total of 215 not-independent general
circulation models from different downscaled datasets illustrated in Figures 1 to 5, show
consistent increases in the magnitude of future extreme rainfall occurrences for the 50-year future
planning horizon represented by change factors larger than 1.0.
• RCP 4.5 AND RCP 8.5 EMISSIONS SCENARIOS: Resulting change factors are slightly
higher in RCP 8.5 than in RCP 4.5 for all downscaled datasets, and in both climate regions,and
not statistically significant. Differences between the medians and percentile results representing
individual RCP versus combined RCP when comparing individual datasets were observed. These
differences between the emission scenarios are amplified,especially for MACA when evaluating
only selected best model results.
• INDIVIDUAL DOWNSCALED DATASETS: The comparison between modeled and observed
records for the historical period showed different degrees of agreement among the selected
datasets and models,without any stand-out condition representing a single dataset that performs
significantly better than others. Overall, as to be detailed in the USGS upcoming publication,
MACA and CORDEX perform better than LOCA in reproducing climate extreme indices.
However,the MACA dataset has been found to amplify the climate change signal in change
factors(Lopez-Cantu et al.2020; Wang et al. 2020)when evaluated over the entire contiguous
United States.
• ALL MODELS OR BEST MODELS: Like the the individual downscaled datasets observation
above,the comparison between a subset of best models versus all models,as illustrated in
Figures 2 to 5, showed different degrees of agreement.Because of its performance results, a
larger set of MACA downscaled models was included in the subset of best models,resulting in
overall larger change factors in the subset of best models when compared to all models.
• RESULT RANGES: There is a noticeable wide spread of derived change factors,with distinct
ranges of confidence intervals(50%, 68%, and 90% confidence intervals). The large spread in the
derived change factors is potentially a result of the relatively coarse resolution,difference
between statistical and dynamic downscaling approaches,biases in historically fitted DDF
curves,' and scenario spread.
• INDIVIDUAL RAINFALL STATIONS OR REGIONAL ANALYSES: There is noticeable
variation between individual rainfall stations within rainfall areas.Median change factors across
selected regions,with respective spread, are recommended to reduce uncertainty associated with
estimated values at individual stations.
' The biases in historically fitted DDF curves were calculated by comparing the historical modeled results
from the selected global climate model downscaled datasets with observations.The concept is illustrated
in Figure 1.
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165
OVERALL RECOMMENDATIONS
Based on the interpretation of the results from the USGS data release (Irizarry-Ortiz and Stamm 2022)and
overall observations and findings compiled by the Future Extreme Rainfall Projections Technical
Workgroup,the SFWMD is recommending the adoption of future extreme rainfall change factors as part
of scenario formulation processes for flood vulnerability studies and resiliency planning efforts as follows:
INCREASING FUTURE EXTREME RAINFALL: Because the majority of results show
increases in the magnitude of future extreme rainfall occurrences for the 50-year planning
horizon,change factors larger than 1.0 are to be adopted as part of scenario formulation, as
summarized below.
RCP 4.5 AND RCP 8.5 SCENARIOS: Due to the observed overlap in the results for RCP 4.5
and RCP 8.5 scenarios for all datasets and all models,combined change factors are to be adopted
as part of scenario formulation.
ENSEMBLE ESTIMATES: Because no stand-out characteristic representing a single dataset
was identified to justify its selection as representative of future extreme rainfall conditions,the
model spread of all available results is to be adopted as part of scenario formulation. The
ensemble results,of a group of climate model simulations, are being adopted to determine the
projections median change factors for precipitation depths as well as model spread at locations
throughout South Florida.An ensemble of the different climate scenarios capturing upper and
lower bounds of climate scenarios is considered a reasonable approach to represent relative
results uncertainty.
ALL MODELS: Because the subset of best models is biased towards the MACA results,which
seem to amplify the climate signal,the ensemble estimates based on all the model results,instead
of the subset of best models,are to be adopted as part of scenario formulation.
50%CONFIDENCE INTERVAL FOR MODEL SPREAD: Because there is a noticeable
wide spread of derived change factors,the 50%confidence interval(related to model sampling)is
being adopted to represent model spread,by delineating a 25t1'percentile lower and a 75'1'
percentile upper range, and to limit the scenario formulation process to the 50%confidence
region representing the central tendency around the median values. The adoption of future
extreme rainfall change factors outside of the 50%confidence interval might result in under
and/or over estimation of future extreme rainfall depths as part of flood vulnerability planning
processes.
RESULTS BY REGION: Because there is noticeable variation between individual rainfall
stations,median change factors across selected regions with respective spread are to be adopted
as part of scenario formulation.For smaller scale planning efforts, an individual station change
factor might be applied,available at the USGS data release portal.
As a result of these initial recommendations,change factors for the 25t1i and 75'1i percentile(50%confidence
range)were pre-calculated for each SFWMD rainfall area, as well as for each county within the SFWMD
boundaries,using ensemble estimates based on the results of all the models,and for combined RCP 4.5 and
RCP 8.5 scenarios. The median results (50t1i percentile change factors) are listed in Tables I and 2 for
counties and rainfall areas.Figure 7 shows the 16 counties within the SFWMD boundaries,color coded by
the computed change factors for 1-day duration and 100-year return frequency, based on the 50%
confidence interval(within the 25t1i and 75'1i percentile)for the ensemble of all model results and combined
emissions scenarios (RCP 4.5 and RCP 8.5). Figure 8 shows the 14 SFWMD rainfall areas, as well as
Everglades National Park,and an additional combined rainfall area for the Florida Keys and Biscayne Bay,
color coded by the computed change factors for 1-day duration and 100-year return frequency, based on
the 50% confidence interval (within the 25t1i and 75'1i percentile) for the ensemble of all model results and
10
166
combined emissions scenarios(RCP 4.5 and RCP 8.5).Appendix A and C include a table with the 25t1i and
75"'percentile ranges for the counties and rainfall areas, respectively. Appendix B and D include graphs
showing the median (50t1 percentile) and 25' and 75'percentile ranges for the counties and rainfall areas
for the 1-day and 3-day durations.These results are also available through the SFWMD Resilience Metrics
Hub's Future Extreme Rainfall Change Factors for Flood Resiliency Planning in South Florida Web App.
The entire set of results for each global climate model dataset and additional percentile ranges are available
at the USGS ScienceBase data release portal: hips://doi.orm/10.5066/P935WRTG.
Additional professional judgment for the adoption of future extreme rainfall change factors as part of flood
vulnerability studies and resiliency planning efforts is applicable and should employ methods for decision
making under uncertainty and flexible planning approaches.Planned phasing and flexible designs for flood
adaptation solutions might reduce long-term costs while considering the evolution in climate science and
next steps in the determination of future extreme rainfall conditions.
Table 1. Computed median change factors for counties.
Duration Return Period
County' (days) 5-year 10-year 25-year 50-year 100-year
1 1.11 1.13 1.17 1.21 1.25
Broward 3 1.08 1.12 1.16 1.20 1.23
7 1.06 1.09 1.13 1.17 1.19
1 1.12 1.16 1.23 1.28 1.35
Charlotte 3 1.11 1.15 1.21 1.26 1.31
7 1.08 1.11 1.16 1.20 1.24
1 1.11 1.14 1.18 1.21 1.25
Collier 3 1.08 1.11 1.15 1.19 1.23
7 1.04 1.07 1.12 1.15 1.19
1 1.11 1.14 1.17 1.19 1.22
Glades 3 1.09 1.11 1.15 1.17 1.20
7 1.05 1.08 1.13 1.16 1.19
1 1.10 1.13 1.17 1.20 1.24
Hendry 3 1.08 1.11 1.15 1.18 1.21
7 1.05 1.08 1.12 1.15 1.18
1 1.13 1.16 1.20 1.23 1.26
Highlands 3 1.11 1.14 1.19 1.23 1.27
7 1.07 1.11 1.17 1.22 1.26
1 1.12 1.15 1.19 1.25 1.29
Lee 3 1.09 1.13 1.17 1.21 1.26
7 1.05 1.08 1.12 1.17 1.21
1 1.10 1.12 1.15 1.17 1.19
Martin 3 1.09 1.12 1.15 1.17 1.18
7 1.07 1.11 1.14 1.16 1.19
1 1.09 1.12 1.16 1.18 1.21
Miami-Dade 3 1.06 1.10 1.14 1.18 1.21
7 1.05 1.08 1.14 1.18 1.22
1 1.08 1.10 1.14 1.16 1.19
Monroe2 3 1.05 1.07 1.11 1.14 1.18
7 1.03 1.07 1.10 1.13 1.16
1 1.12 1.14 1.18 1.20 1.23
Okeechobee 3 1.10 1.13 1.17 1.20 1.24
7 1.00 1.11 1.17 1.20 1.24
1 1.16 1.19 1.22 1.25 1.28
Orange 3 1.13 1.16 1.20 1.23 1.26
7 1.12 1.15 1.21 1.24 1.29
Osceola 1 1.15 1.17 1.19 1.20 1.22
3 1.12 1.14 1.18 1.20 1.22
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Duration Return Period
County' (days) 5-year 10-year 25-year 50-year 100-year
7 1.10 1.14 1.18 1.22 1.26
1 1.10 1.13 1.17 1.20 1.21
Palm Beach 3 1.09 1.12 1.15 1.17 1.20
7 1.07 1.09 1.14 1.17 1.19
1 1.15 1.17 1.21 1.24 1.26
Polk 3 1.12 1.15 1.19 1.23 1.27
7 1.09 1.13 1.19 1.23 1.28
1 1.11 1.13 1.15 1.18 1.21
St. Lucie 3 1.10 1.13 1.15 1.18 1.20
7 1.09 1.12 1.15 1.18 1.21
Data are based on the results published in the USGS data release by Irizarry-Ortiz and Stamm(2022).
2 Florida Keys station data are included in the estimates for the Florida Keys and Biscayne Bay rainfall area,but the
change factors for these stations were determined for the closest climate model grid cell on the mainland.
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168
Hamosasss
springs W
Spring Hitt or d.qje county
Lak Osceola County
Clearwater Tampa Polk County
St
Petersburg
Sarasota Okeechobee County
Martin County
Port OL-
Charlotte Glades County
Charlotte County
Cape Cor�[ Palm Beach County
Lm County Hendry County
VI"1-m.k.'I'ee'
rAiiinli
Miami-Dade County
Percentile 50th
Monroe County >1.278
1.189
feFeo
- <1.101
Figure 7. Map of computed change factors for the 16 counties within the SFWMD boundaries for the
3-day duration and 100-year return frequency,based on the 50%confidence interval(within
the 25t1 and 75h percentile)for the ensemble of all model results and combined emissions
scenarios(RCP 4.5 and RCP 8.5).
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169
Table 2. Computed median change factors for rainfall areas.
Return Period
Rainfall Area' Duration
(days) 5-year 10-year 25-year 50-year 100-year
1 1.10 1.13 1.17 1.21 1.25
Big Cypress Preserve 3 1.08 1.10 1.14 1.18 1.22
7 1.04 1.06 1.11 1.14 1.17
1 1.11 1.14 1.17 1.20 1.24
B rowa rd 3 1.09 1.12 1.17 1.21 1.23
7 1.07 1.10 1.15 1.18 1.21
1 1.11 1.14 1.17 1.22 1.26
East Caloosahatchee 3 1.09 1.12 1.15 1.19 1.22
7 1.05 1.07 1.11 1.15 1.20
1 1.10 1.13 1.16 1.19 1.21
East Everglades Agricultural Area 3 1.09 1.11 1.15 1.17 1.19
7 1.06 1.09 1.13 1.16 1.18
1 1.08 1.11 1.14 1.17 1.20
Everglades National Park 3 1.04 1.07 1.12 1.16 1.19
7 1.03 1.06 1.12 1.16 1.19
1 1.09 1.11 1.14 1.17 1.20
Florida Keys and Biscayne Bayz 3 1.06 1.08 1.11 1.15 1.19
7 1.04 1.07 1.11 1.13 1.17
1 1.09 1.11 1.14 1.17 1.20
Lake Okeechobee 3 1.06 1.08 1.11 1.15 1.19
7 1.04 1.07 1.11 1.13 1.17
1 1.13 1.16 1.19 1.22 1.25
Lower Kissimmee 3 1.11 1.14 1.18 1.22 1.26
7 1.08 1.12 1.17 1.22 1.26
1 1.11 1.13 1.15 1.18 1.20
Martin and St. Lucie 3 1.10 1.12 1.15 1.17 1.20
7 1.08 1.12 1.15 1.17 1.20
1 1.10 1.12 1.16 1.18 1 1.21
Miami-Dade 3 1.07 1.10 1.15 1.18 1.21
7 1.05 1.09 1.15 1.19 1.22
1 1.11 1.14 1.17 1.20 1.22
Palm Beach 3 1.09 1.12 1.15 1.19 1.21
7 1.07 1.09 1.13 1.17 1.20
1 1.12 1.15 1.18 1.23 1 1.27
Southwest Coast 3 1.08 1.12 1.16 1.21 1.25
7 1.05 1.08 1.13 1.17 1.21
1 1.15 1.18 1.21 1.24 1.26
Upper Kissimmee 3 1.13 1.16 1.20 1.23 1.26
7 1.11 1.15 1.20 1.24 1.28
1 1.12 1.15 1.20 1.23 1 1.26
Water Conservation Area 1 &2 3 1.09 1.12 1.17 1.21 1.25
7 1.06 1.10 1.13 1.17 1.20
1 1.09 1.12 1.16 1.19 1.22
Water Conservation Area 3 3 1.07 1.10 1.14 1.17 1.20
7 1.04 1.07 1.12 1.16 1.18
1 1.09 1.13 1.17 1 1.21 1 1.26
West Everglades Agricultural Area 3 1 1.07 1 1.11 1 1.15 1.19 1.22
7 1 1.05 1 1.08 1 1.12 1.15 1.17
Data are based on the results published in the USGS data release by Irizarry-Ortiz and Stamm(2022).
2 Florida Keys station data are included in the estimates for the Florida Keys and Biscayne Bay rainfall area,but the
change factors for these stations were determined for the closest climate model grid cell on the mainland.
14
170
Orlando
Spring Hitt
Upper IlUssimmee
Lakeland Melbourne
Clearwater Tampa Palm Bay
St ---.,k
Petersburg
Lower Kissimmee
Sarasota
OF Martin- ucie
Okeechobee
Miami-DadePort Zo Lake
Charlotte
East Caloosahatchee Palm
Cape Coia, East Everglades Agricultural Area
Soudwiest Coast
C-oral
o
Springs
el
Naples Bro
Big ress Preserve b,'.I e'
Everglades National.
Percentile 50th
> 1.278
Florida Keys and Bi yne Bay
1.189
SFWMD Resiliency Team I University of South Florca,FDE= <1.101
Figure 8. Map of computed change factors for the 14 rainfall areas within the SFWMD boundaries,as well
as Everglades National Park,and a combined Florida Keys and Biscayne Bay rainfall area,for the
3-day duration and 100-year return frequency,based on the 50%confidence interval(within the
25t1i and 75h percentile of models spread)for the ensemble of all model results and combined
emissions scenarios(RCP 4.5 and RCP 8.5).
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EXAMPLE APPLICATION OF RAINFALL CHANGE FACTORS
A sensitivity analysis was performed using a rainfall change factors threshold approach(20%, 30%,40%,
50%, and 75%increase, as defined in Appendix E)to assess potential future extreme rainfall impacts into
long-term flood protection planning scenarios in southern Broward County (C-8 Basin) and northern
Miami-Dade County (C-9 Basin), for a 72-hour design event of 100-year recurrence frequency. The
sensitivity runs were developed based on integrated groundwater and surface water models of the C-8 and
C-9 basins (i.e.,MIKE SHE and MIKE I 1 models) developed as part of the FPLOS program, to evaluate
current conditions(CC) and potential future sea level rise (SLR)with 1-,2-, and 3-ft impacts.
The FPLOS in the C-8 and C-9 basins was determined through a set of performance metrics(PM)that are
derived from the outputs of the watershed-scale flood event modeling (SFWMD 2022). These PMs
highlight deficiencies of the system and assign a FPLOS rating. Two of these FPLOS PMs include the
analysis of maximum discharge capacity through the canals(PMI)and depth of flooding(PM5).
Results presented in PMI for the C-8 and C-9 canals indicate an overall increase in water elevations from
0.1 ft to I ft,corresponding to the 20%to 75%increase in future extreme rainfall estimates.Table 3 includes
the relationship between rainfall change factors and increase in water elevation for the C-8 and C-9 profiles
and across both basins.
Table 3. Relationship between rainfall change factors and increased flood depths for the C-8 profile,
C-9 profile,and across both basins combined.
Increases in Water Elevation feet
Rainfall (feet)
Change Factor Threshold C-8 Profile (PM1) C-9 Profile (PM1) C-8 and C-9 Basins(PM5)
20% =0.1 -0.25 =0.1 —0.2 =0.2-0.3
30% =0.25-0.4 =0.2-0.3 =0.3-0.4
40% =0.4-0.55 =0.3-0.4 =0.4-0.5
50% =0.55-0.7 =0.4-0.55 =0.5-0.6
75% =0.7-1.0 =0.55-0.8 =0.6- 1.0
Additionally, the root mean square difference (RMSD) was applied to PMI to analyze the correlation
between model results, with the goal of finding different combinations of high magnitude rainfall change
factors with lower SLR scenarios that may produce "equivalent" outcomes to low magnitude rainfall
increase with higher SLR scenarios.Figure 9 compares maximum water surface profiles between CC 75%,
SLRI + 50%, SLR2 + 40%, and SLR3 + 30%. Results display that the downstream reach (z 10,000-ft
distance from the end of reach)is particularly vulnerable to the influence of tidal forcing,resulting in higher
differences compared to the "inland" canal profile. The sampled profiles produce lower RMSD (values
closer to 0) when the water surface elevation is compared only to the length that is not affected by the
impacts of SLR. It should be noted that the ability of the model to simulate the downstream area is limited
to the enforced boundary conditions at structures S-28 (C-8 Canal) and S-29 (C-9 Canal) as the structure
operational levels play a key role in allowing the tidal conditions to influence the canal water surface
elevation upstream the structure (Taylor Engineering 2021).
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172
C-9 Canal 100-Year Future Conditions Design Storm
Maximum Water Surface Profile;Current Conditions vs SLR123 k --•cc_7s --•sutL_so
10.00
-noNF arnk -scwkx
IM I�
L` r
8.00
7.00 — — - __ — ;�--
a 1._ V
r
v
I-95 Express(88Q00 ft)
CC 20
CC 30
CC 40 CC_50 cC_75 SI
085,00-8LR1 0.990 0.091 0.187 0.273 0.527
SLRi�0 0.082 0.074 0.227
SLRi 30 0.023 0.127
8LR7 40
SLR1 50
4.00-SLR2 0.050 0.108
SLR2 20 0.100
SLR2 30
SLR2 40
SLR2 so 3 +
3.00-OLR3 0.024 0.120 k
SLR3 20 9 �• M
SLRO 30 3 S
r'SLR3 40
L SLR3 s0
Yi li 0 4 kF 3 $ 9 8 $ $
LEGEND
0-0.02 0.02.0.2 Similar 1 0.2+ Different L rdm ks along C•9 C.n.I
Dirt....form Upsi na.m End of Rath[R[
Figure 9. C-9 Canal peak stage profiles for 100-year 72-hour design storm using four rainfall change factors
(75%, 50%,40%,and 30%)that are paired with SLR scenarios(CC, SLRI, SLR2,and SLR3). The
RMSD(lower left)values illustrate the similarities(green)and differences(yellow)between water
surface elevation profiles using different combinations of rainfall change factors and SLR scenarios_
Results show that CC 75%, SLRI 50%, SLR2 40%,and SLR3 30%scenarios produce consistent water
surface elevations on the"inland"canal profile(red horizontal line),from upstream to Interstate 95.
Regarding PM5,depth of flooding,results suggest that rainfall change factors produce a similar increase in
percent for higher inundation depths, aggravating widespread flooding conditions across both basins.
Figure 10 illustrates the maximum inundation depths corresponding to the impacts of the SLR3 senario
with a 20% rainfall increase, which represents the overall median flooding conditions across the C-8 and
C-9 basins. The simulation demonstrates a slight increase in overland flooding depths (0.25 ft to 0.35 ft)
with similar inundation extent compared to the SLR3 scenario. It must be noted that the inland portion of
both basins is more resilient to rainfall-induced flooding conditions,specifically the C-9 northwestern area.
Conversely, increases in overland flooding depths are more evident on the coastal boundary as shallow
water tables undermine the soil infiltration capacity. Similarly,an increase in rainfall depths triggers higher
overland flooding near historic waterways(Canal C-8 and C-9) and low-elevation areas.
17
173
SLR3 + 20% Rainfall Increase
a
I
Overland
Flooding 4 '
Depth(ft) _
Q
0-025
�7 0.25-0.5 ...'
.�
0.5-0.75
0.75-1 -
1.00-1,25 L -
�1.25-1.5 �CS I'
1.50-1.75 C9 _ N
1.75-2 —Roads
-2.2 25 Model—Domain Q 1 2 4 Miles
-2.25+ Water&Wetlands
Figure 10. Flood inundation map for 100-year 72-hour design storm event for SLR3 scenario with a
20%rainfall change factor.
Figure 10 shows the impacts of the SLR3 scenario with a 75% rainfall increase, producing the worst
flooding conditions across the C-8 and C-9 basins. Despite considerable increases in overland flooding on
the coastal boundary,the basins mostly experience low to moderate flooding conditions(0.25 ft to 1.00 ft),
as zones that experience more critical flooding conditions are mainly identified in areas subject to riverine
flooding due to overbank flow and from coastal zones(above 2.25 ft),while the overland flooding depth in
urban areas within 8 miles from the coast oscillates between 1.00 ft and 1.50 ft. Similarly, results also
illustrate that transition zones (i.e., zones that are influenced by rainfall and coastal processes) are highly
vulnerable to compound flood hazards as a result of the interaction of multiple pluvial, fluvial,
oceanographic, and groundwater processes in similar spatial and temporal scales. Appendix E contains a
more detailed report summarizing the approach and overall results of the rainfall sensitivity analysis.
18
174
SLR3 + 75% Rainfall Increase
I
' A�
i
I _
Overland g
AI
Floodin
Depth(ft) r
�0-015
D.25-0-5
0.5-0.75 — —
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1.00-1.25 —
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1.50-1.75 C9 N
175.2
—Roads r. •
_2-2.25 Mode[—Domain D 1 2 4 Miles
-
2.25- Water&Wetlands
Figure 11. Flood inundation map for 100-year 72-hour design storm event for SLR3 scenario with a 75%rainfall
change factor.
A more detailed analysis is required to fully characterize the contribution of individual flood drivers
(rainfall, river discharge, tide levels, water table, and SLR) in terms of inundation depth and extent to
transition zones and overall basin impacts. Similar assessments that focus on understanding long-term
changes in precipitation may provide insights on the system performance,structural failure,and operational
practices, potentially serving as a planning tool to inform engineers and decision makers on the
development of prevention,mitigation, and adaptation strategies to build local resilience.
19
175
Current Conditions+75%Rainfall Increase SLR1 +50%Rainfall Increase
iboJlrq �IooJlrq
SLR2+40%Rainfall Increase SLR3+30%Rainfall Increase
� f
7.
23�
Wnm
rte. ���]].•,�..�..,.. °° "v`•.. � �,.. �.«A,ti,.....« v""°'
Figure 12. Maximum flood inundation depths(0 to>2.25 feet)of four different scenario combinations(CC+
75%, SLRl +50%, SLR2+40%,and SLR3+30%)and rainfall change factors in the C-8(gray
dashed line)and C-9(magenta dashed line)basins. The transition zone(red circle)is highly vulnerable
to the combined impacts of multiple flood drivers(rainfall,river discharge,tides,and water table)as a
result of its low-elevation coastal zone, shallow water table,and complex hydrogeology_Flood maps
illustrate that flood inundation depths are more similar"inland"compared to the coastal portion of the
domain,which is exacerbated by the impact of SLR.
20
176
CONCLUSIONS
Quality of life in South Florida is highly dependent on effective and equitable water management. Since
the late 1800s, when water management systems started to be constructed and allowed land development
in areas previously inundated throughout most of the year, the region has been making significant
investments in water management infrastructure and implemented one of the most complex and largest
water management systems in the world. The Central and Southern Florida(C&SF)Project was authorized
by the Flood Control Act of 1948 for the purposes of flood control, regional water supply, prevention of
saltwater intrusion, navigation, recreation, and protection and preservation of fish and wildlife resources.
The USACE,jointly with the SFWMD (the C&SF Project nonfederal sponsor), are responsible for the
C&SF Project operation and maintenance.
Due to significantly changed physical, climatological, demographic, and economic conditions, within the
basins served by the C&SF Project system, the associated water management infrastructure has been
providing reduced capacity to address project purposes.Advanced flood vulnerability assessments are being
performed as part of the FPLOS program and are accounting for sea level rise. With higher certainty that
temperatures will continue to increase over the coming decades, as documented in the IPCC Sixth
Assessment Report (2022), it is important that resultant changes in rainfall be assessed. Determining the
future rainfall scenarios to be incorporated as part of the FPLOS assessments and other regional and local
flood vulnerability assessments in South Florida is critical to support resiliency planning efforts, and to
properly account for rainfall driven flooding risks,in addition to sea level rise driven flooding risks.
To support the development of future extreme rainfall scenarios, the SFWMD entered into a cooperative
agreement with the USGS Caribbean—Florida Water Science Center and the FIU Sea Level Solutions Center
to develop future depth-duration-frequency curves for the 16 counties the District oversees based on
available global climate model downscaled datasets.The results from the USGS data release(Irizarry-Ortiz
and Stamm 2022) show a noticeable wide spread of derived change factors, with distinct ranges of
confidence between individual model datasets and a subset of best models,representing uncertainty from
overall global climate modeling, emission scenario formulation, and downscaling approaches, as well as
natural variability that pertains to rainfall occurrence in Florida. To adopt these results as part of ongoing
resiliency planning efforts, the Future Extreme Rainfall Projections Technical Workgroup conducted a
review process that resulted in a summary of overall observations and key findings, as well as initial
recommendations summarized in this technical memorandum.
The criteria for results selection and initial scenario formulation were based on technical consensus upon
the evaluation of the available results and the best approach to represent and incorporate associated
uncertainty. This technical memorandum contains recommended change factors based on the adoption of
the 50% confidence interval of the models sample (25t1i and 75'1i percentile range) for 1-, 3-, and 7-day
duration and 5-, 10-, 25-, 50-, 100-, and 200-year return frequency using the ensemble of all model results
for two combined emissions scenarios(RCP 4.5 and RCP 8.5)compiled for the 16 counties and 14 rainfall
areas within the SFWMD boundaries as well as the Everglades National Park rainfall area,and an additional
combined rainfall area for the Florida Keys and Biscayne Bay.
While higher resolution regional rainfall projections are being developed as part of a longer-term initiative
to reduce uncertainty as agreed upon at the Workshop Report and Strategy Document: Development of
Unified Rainfall Scenarios for Florida(FIU 2019) the adoption of future extreme rainfall change factors
developed through the SFWMD/USGS/FIU partnership and summarized in this technical memorandum is
encouraged as part of flood resiliency planning efforts. With the goal of facilitating data accessibility to
partner agencies and to the public, advancement of common practices, comparison of evaluations, and
regional consistency,the results are made available through the SFWMD Resilience Metrics Hub's Future
Extreme Rainfall Change Factors for Flood Resiliency Planning in South Florida Web App. Both the
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177
current results and development of next steps are being coordinated with the statewide efforts of the
Resilient Florida Program,the Florida Flood Hub for Applied Research and Innovation at the University of
South Florida College of Marine Science, other water management districts, regional planning councils,
and local and state agencies to achieve best resiliency planning standards for South Florida.
Restatement of Use:
This technical memorandum provides initial guidance and example application to aid planning practices on
how to apply estimated change factors to account for future extreme rainfall events as part of local and
regional flood vulnerability assessments. The data provided herein are considered applicable within the
SFWMD boundaries and should be rigouroulsy interpreted in the context of each particular application.
Users are fully responsible for the application of the data. The results, and associated recommendations
included in this memorandum, are not providing the necessary level of resolution that would be applicable
to advance modernization of design criteria or to inform regulatory programs; therefore, these are not
included as part of a District's mandate. Change factors were computed from 40-year periods representing
future projected climate for the period 2050-2089 (centered in 2070) and historical (retrospective)
conditions for 1966-2005 and might be derived to represent planning scenarios within SFWMD
boundaries. This technical memorandum is provisional pending the publication of the final report to be
published by the USGS.
22
178
LITERATURE CITED
Florida International University.2019. Workshop Report and Strategy Document:Development of Unified
Rainfall Scenarios for Florida. Available online at https:Henvironment.fiu.edu/what-we-
study//projects/rainfall-workshop/as of April 2022.
Intergovernmental Panel on Climate Change. 2022. Climate Change 2022 Impacts, Adaptation and
Vulnerability. Summary for Policymakers,IPCC WGII Sixth Assessment Report.Available online
at https://www.ipcc.ch/report/sixth-assessment-report-working-group-ii/as of April 2022.
Irizarry-Ortiz, M.M. and J.F. Stamm. 2022. Change Factors to Derive Future Precipitation Depth-
Duration-Frequency (DDF) Curves at 174 National Oceanic and Atmospheric Administration
(NO, A) Atlas 14 Stations in Central and South Florida. United States Geological Survey Data
Release.Available online at https://doi.org/10.5066/P935WRTG as of April 2022.
Irizarry, M.M., J. Obeysekera, and T. Dessalegne. 2016. Determination of Future Intensity-Duration-
Frequency Curves for Level of Service Planning Projects. Task 2: Deliverable 2.1 Conduct an
extreme rainfall analysis in climate model outputs to determine temporal changes in IDF curves.
Technical Publication, Purchase Order 4500095433. South Florida Water Management District,
West Palm Beach,FL.
Lopez-Cantu,T.,A.F.Prem,and C. Samaras.2020.Uncertainties in future U.S.extreme precipitation from
downscaled climate projections. Geophysical Research Letters dol: 10.1029/2019GL086797.
Perica,S.,D.Martin,S.Paclovoc,L Roy,M.St.Laurent,C.Trypaluk,D.Unruh,M.Yekta,and G.Bonnin.
2013. NOAA Atlas 14 Volume 9 Version 2, Precipitation-Frequency Atlas of the United States,
Southeastern States. NOAA, National Weather Service, Silver Spring, MD. Available online at
haps://repositoiy.librM.noaa.gov/view/noaa/22617 as of April 2022.
SFWMD. 2022.South Florida Environmental Report. Volume 1, Chapter 2B. Pages 213-9 through 213-43.
South Florida Water Management District, West Palm Beach, FL. Available online at
haps://www.sfwmd.gov/science-data/scientific-publications-sfer as of April 2022.
Taylor Engineering. 2021. Flood Protection Level of Service Provided by Existing Infrastructure for
Current and Future Sea Level Conditions in the C8 and C9 Watersheds Draft Final Comprehensive
Report. Deliverable 5.2, Contract 4600004085. South Florida Water Management District, West
Palm Beach,FL.
Wang G., C.J. Kirchhoff, A. Seth, J.T. Abatzoglou, B. Livneh, D.W. Pierce, L. Fomenko, and T. Ding.
2020. Projected changes of precipitation characteristics depend on downscaling method and
training data: MACA versus LOCA using the U.S. northeast as an example. Journal of
Hydrometeorology dol: 10.1175/JHM-D-19-0275.1.
Yin,C.,Y.Li,and P.Urich. 2019.Appendix B: The Broward County DDF Project—Technical Summary.
CLIMsystems,Hamilton,New Zealand.In:Future Rainfall Development Technical Memorandum,
Future Conditions 100-Year Flood Elevation Map. Geosyntec Consultants, Inc. Winter Springs,
FL,2020.
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180
APPENDIX A: TABLE OF COMPUTED CHANGE FACTORS FOR
COUNTIES IN THE SFWMD BOUNDARIES
The table below summarizes the computed change factors for the 16 counties within the SFWMD
boundaries for the 1-, 3-, and 7-day durations and the 5-, 10-, 25-, 50-, 100-, and 200-year return
frequencies,based on the 50% confidence interval (within the 25t'and 75t'percentile) for the ensemble of
all model results and combined emissions scenarios (RCP 4.5 and RCP 8.5).
County Duration Return Period 25th Percentile 50th Percentile 75th Percentile
(days) (years)
B rowa rd 1 5 1.01 1.11 1.21
1 10 1.02 1.13 1.27
1 25 1.02 1.17 1.36
1 50 1.02 1.21 1.44
1 100 1.01 1.25 1.53
1 200 1.01 1.28 1.62
3 5 1.01 1.08 1.18
3 10 1.01 1.12 1.25
3 25 1.01 1.16 1.33
3 50 1.01 1.20 1.39
3 100 1.01 1.23 1.48
3 200 1.01 1.26 1.60
7 5 0.99 1.06 1.16
7 10 1.00 1.09 1.22
7 25 1.00 1.13 1.32
7 50 1.00 1.17 1.38
7 100 0.99 1.19 1.48
7 200 0.98 1.23 1.60
Charlotte 1 5 1.03 1.12 1.23
1 10 1.04 1.16 1.31
1 25 1.05 1.23 1.40
1 50 1.06 1.28 1.50
1 100 1.06 1.35 1.63
1 200 1.06 1.39 1.80
3 5 1.02 1.11 1.20
3 10 1.04 1.15 1.26
3 25 1.04 1.21 1.38
3 50 1.05 1.26 1.48
3 100 1.04 1.31 1.59
3 200 1.06 1.35 1.74
7 5 0.99 1.08 1.16
7 10 0.99 1.11 1.22
7 25 1.01 1.16 1.33
7 50 1.02 1.20 1.42
7 100 1.00 1.24 1.55
7 200 1.00 1.28 1.69
Collier 1 5 1.01 1.11 1.21
1 10 1.02 1.14 1.27
1 25 1.02 1.18 1.39
1 50 1.02 1.21 1.48
1 100 1.02 1.25 1.58
1 200 1.01 1.30 1.70
3 5 1.00 1.08 1.16
3 10 1.00 1.11 1.22
3 25 1.00 1.15 1.31
3 50 1.00 1.19 1.40
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181
County Duration Return Period 25th Percentile 50th Percentile 75th Percentile
(days) (years)
3 100 1.00 1.23 1.51
3 200 0.99 1.27 1.63
7 5 0.96 1.04 1.11
7 10 0.97 1.07 1.17
7 25 0.97 1.12 1.26
7 50 0.97 1.15 1.35
7 100 0.97 1.19 1.45
7 200 0.96 1.23 1.57
Glades 1 5 1.02 1.11 1.22
1 10 1.02 1.14 1.27
1 25 1.02 1.17 1.35
1 50 1.01 1.19 1.41
1 100 1.00 1.22 1.48
1 200 0.99 1.24 1.56
3 5 1.01 1.09 1.17
3 10 1.01 1.11 1.22
3 25 1.01 1.15 1.29
3 50 1.00 1.17 1.37
3 100 0.99 1.20 1.45
3 200 0.98 1.22 1.53
7 5 0.98 1.05 1.14
7 10 0.99 1.08 1.19
7 25 0.99 1.13 1.28
7 50 0.98 1.16 1.36
7 100 0.98 1.19 1.45
7 200 0.97 1.23 1.55
Hendry 1 5 1.01 1.10 1.22
1 10 1.03 1.13 1.29
1 25 1.03 1.17 1.38
1 50 1.03 1.20 1.45
1 100 1.02 1.24 1.53
1 200 1.01 1.27 1.63
3 5 1.00 1.08 1.17
3 10 1.01 1.11 1.23
3 25 1.02 1.15 1.32
3 50 1.02 1.18 1.40
3 100 1.01 1.21 1.48
3 200 1.00 1.24 1.57
7 5 0.98 1.05 1.13
7 10 0.99 1.08 1.19
7 25 1.00 1.12 1.27
7 50 0.99 1.15 1.36
7 100 0.99 1.18 1.45
7 200 0.99 1.21 1.54
Highlands 1 5 1.04 1.13 1.22
1 10 1.05 1.16 1.29
1 25 1.05 1.20 1.38
1 50 1.05 1.23 1.46
1 100 1.05 1.26 1.55
1 200 1.05 1.29 1.65
3 5 1.02 1.11 1.19
3 10 1.03 1.14 1.25
3 25 1.04 1.19 1.35
3 50 1.05 1.23 1.44
3 100 1.05 1.27 1.53
3 200 1.04 1.31 1.64
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182
County Duration Return Period 25th Percentile 50th Percentile 75th Percentile
(days) (years)
7 5 1.00 1.07 1.16
7 10 1.01 1.11 1.22
7 25 1.02 1.17 1.33
7 50 1.02 1.22 1.44
7 100 1.03 1.26 1.56
7 200 1.03 1.32 1.67
Lee 1 5 1.03 1.12 1.23
1 10 1.03 1.15 1.31
1 25 1.04 1.19 1.43
1 50 1.04 1.25 1.54
1 100 1.04 1.29 1.65
1 200 1.03 1.33 1.81
3 5 1.01 1.09 1.18
3 10 1.03 1.13 1.25
3 25 1.02 1.17 1.37
3 50 1.01 1.21 1.48
3 100 1.00 1.26 1.60
3 200 0.99 1.32 1.73
7 5 0.98 1.05 1.14
7 10 0.99 1.08 1.19
7 25 0.99 1.12 1.31
7 50 0.99 1.17 1.42
7 100 0.98 1.21 1.54
7 200 0.96 1.25 1.69
Martin 1 5 1.00 1.10 1.21
1 10 1.01 1.12 1.25
1 25 1.01 1.15 1.31
1 50 1.00 1.17 1.36
1 100 1.00 1.19 1.43
1 200 0.99 1.21 1.48
3 5 1.01 1.09 1.18
3 10 1.01 1.12 1.23
3 25 1.01 1.15 1.29
3 50 1.01 1.17 1.36
3 100 1.00 1.18 1.43
3 200 0.99 1.19 1.50
7 5 1.00 1.07 1.16
7 10 1.01 1.11 1.21
7 25 1.00 1.14 1.30
7 50 0.98 1.16 1.36
7 100 0.96 1.19 1.45
7 200 0.94 1.22 1.55
Miami-Dade 1 5 1.00 1.09 1.21
1 10 1.00 1.12 1.26
1 25 0.99 1.16 1.33
1 50 0.99 1.18 1.39
1 100 0.99 1.21 1.47
1 200 0.98 1.23 1.56
3 5 0.99 1.06 1.19
3 10 0.99 1.10 1.24
3 25 0.99 1.14 1.32
3 50 0.99 1.18 1.40
3 100 0.99 1.21 1.48
3 200 0.98 1.25 1.56
7 5 0.97 1.05 1.15
7 10 0.98 1.08 1.22
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183
County Duration Return Period 25th Percentile 50th Percentile 75th Percentile
(days) (years)
7 25 0.99 1.14 1.32
7 50 0.99 1.18 1.42
7 100 0.98 1.22 1.55
7 200 0.97 1.27 1.68
Monroe' 1 5 0.99 1.08 1.21
1 10 1.00 1.10 1.27
1 25 0.99 1.14 1.36
1 50 0.98 1.16 1.43
1 100 0.98 1.19 1.49
1 200 0.97 1.23 1.56
3 5 0.98 1.05 1.18
3 10 0.98 1.07 1.23
3 25 0.97 1.11 1.31
3 50 0.97 1.14 1.37
3 100 0.95 1.18 1.44
3 200 0.95 1.22 1.51
7 5 0.96 1.03 1.15
7 10 0.96 1.07 1.20
7 25 0.95 1.10 1.27
7 50 0.94 1.13 1.36
7 100 0.93 1.16 1.45
7 200 0.92 1.17 1.57
Okeechobee 1 5 1.02 1.12 1.22
1 10 1.03 1.14 1.28
1 25 1.02 1.18 1.36
1 50 1.02 1.20 1.43
1 100 1.02 1.23 1.51
1 200 1.02 1.26 1.59
3 5 1.02 1.10 1.19
3 10 1.02 1.13 1.25
3 25 1.02 1.17 1.34
3 50 1.03 1.20 1.41
3 100 1.02 1.24 1.50
3 200 1.02 1.28 1.59
7 5 1.00 1.07 1.16
7 10 1.01 1.11 1.22
7 25 1.02 1.17 1.31
7 50 1.02 1.20 1.40
7 100 1.02 1.24 1.50
7 200 1.01 1.28 1.62
Orange 1 5 1.07 1.16 1.25
1 10 1.08 1.19 1.30
1 25 1.08 1.22 1.39
1 50 1.07 1.25 1.46
1 100 1.05 1.28 1.56
1 200 1.05 1.29 1.65
3 5 1.06 1.13 1.20
3 10 1.07 1.16 1.27
3 25 1.07 1.20 1.37
3 50 1.06 1.23 1.45
3 100 1.06 1.26 1.54
3 200 1.05 1.29 1.63
7 5 1.04 1.12 1.18
7 10 1.05 1.15 1.26
7 25 1.06 1.21 1.37
7 50 1.06 1.24 1.46
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184
County Duration Return Period 25th Percentile 50th Percentile 75th Percentile
(days) (years)
7 100 1.07 1.29 1.58
7 200 1.07 1.33 1.71
Osceola 1 5 1.06 1.15 1.24
1 10 1.06 1.17 1.27
1 25 1.06 1.19 1.33
1 50 1.05 1.20 1.40
1 100 1.04 1.22 1.47
1 200 1.02 1.23 1.54
3 5 1.05 1.12 1.20
3 10 1.05 1.14 1.24
3 25 1.05 1.18 1.31
3 50 1.04 1.20 1.38
3 100 1.03 1.22 1.47
3 200 1.01 1.25 1.56
7 5 1.03 1.10 1.18
7 10 1.04 1.14 1.23
7 25 1.05 1.18 1.34
7 50 1.05 1.22 1.42
7 100 1.05 1.26 1.53
7 200 1.05 1.30 1.65
Palm Beach 1 5 1.01 1.10 1.21
1 10 1.01 1.13 1.27
1 25 1.01 1.17 1.36
1 50 1.01 1.20 1.44
1 100 1.01 1.21 1.51
1 200 1.00 1.24 1.60
3 5 1.00 1.09 1.18
3 10 1.01 1.12 1.24
3 25 1.01 1.15 1.33
3 50 1.01 1.17 1.40
3 100 1.00 1.20 1.49
3 200 1.00 1.23 1.59
7 5 0.99 1.07 1.15
7 10 1.00 1.09 1.21
7 25 1.00 1.14 1.30
7 50 0.99 1.17 1.38
7 100 0.98 1.19 1.48
7 200 0.97 1.22 1.57
Polk 1 5 1.07 1.15 1.25
1 10 1.08 1.17 1.30
1 25 1.08 1.21 1.38
1 50 1.07 1.24 1.44
1 100 1.06 1.26 1.52
1 200 1.05 1.29 1.61
3 5 1.05 1.12 1.20
3 10 1.06 1.15 1.26
3 25 1.06 1.19 1.35
3 50 1.05 1.23 1.43
3 100 1.05 1.27 1.52
3 200 1.04 1.30 1.61
7 5 1.02 1.09 1.17
7 10 1.04 1.13 1.24
7 25 1.05 1.19 1.35
7 50 1.05 1.23 1.43
7 100 1.05 1.28 1.54
7 200 1.05 1.32 1.65
A-5
185
County Duration Return Period 25th Percentile 50th Percentile 75th Percentile
(days) (years)
St. Lucie 1 5 1.02 1.11 1.21
1 10 1.02 1.13 1.25
1 25 1.02 1.15 1.32
1 50 1.01 1.18 1.38
1 100 1.01 1.21 1.44
1 200 0.99 1.23 1.50
3 5 1.01 1.10 1.18
3 10 1.02 1.13 1.24
3 25 1.02 1.15 1.30
3 50 1.01 1.18 1.36
3 100 1.01 1.20 1.45
3 200 1.00 1.22 1.54
7 5 1.01 1.09 1.16
7 10 1.02 1.12 1.22
7 25 1.02 1.15 1.30
7 50 1.02 1.18 1.38
7 100 1.00 1.21 1.48
7 200 1.00 1.24 1.57
1 Florida Keys station data are included in the estimates for Monroe County,but the change factors for these
stations were determined based on the closest climate model grid cell on the mainland.
A-6
186
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APPENDIX C: TABLE OF COMPUTED CHANGE FACTORS FOR
SFWMD RAINFALL AREAS
The table below summarizes the computed change factors for the 14 SFWMD rainfall areas, as well as
Everglades National Park, and an additional combined rainfall area for the Florida Keys and Biscayne Bay,
for the 1-, 3-, and 7-day durations and the 5-, 10-,25-, 50-, 100-, and 200-year return frequencies,based on
the 50% confidence interval (within the 25t' and 75t'percentile) for the ensemble of all model results and
combined emissions scenarios (RCP 4.5 and RCP 8.5).
Rainfall Area Duration Return Period 25' Percentile 5011 Percentile 7511 Percentile
(days) (years)
Big Cypress 1 5 1.01 1.10 1.20
Preserve 1 10 1.02 1.13 1.27
1 25 1.03 1.17 1.39
1 50 1.02 1.21 1.48
1 100 1.01 1.25 1.58
1 200 1.01 1.30 1.70
3 5 1.00 1.08 1.16
3 10 1.00 1.10 1.22
3 25 1.01 1.14 1.31
3 50 1.01 1.18 1.40
3 100 1.01 1.22 1.50
3 200 1.01 1.25 1.61
7 5 0.96 1.04 1.11
7 10 0.97 1.06 1.17
7 25 0.97 1.11 1.26
7 50 0.97 1.14 1.34
7 100 0.97 1.17 1.44
7 200 0.96 1.21 1.54
B rowa rd 1 5 1.01 1.11 1.21
1 10 1.02 1.14 1.28
1 25 1.02 1.17 1.36
1 50 1.00 1.20 1.44
1 100 1.00 1.24 1.52
1 200 0.99 1.27 1.60
3 5 1.00 1.09 1.20
3 10 1.01 1.12 1.26
3 25 1.01 1.17 1.34
3 50 1.01 1.21 1.40
3 100 1.00 1.23 1.49
3 200 0.99 1.26 1.60
7 5 1.00 1.07 1.17
7 10 1.01 1.10 1.24
7 25 1.00 1.15 1.33
7 50 1.00 1.18 1.40
7 100 0.99 1.21 1.50
7 200 0.98 1.25 1.61
East 1 5 1.02 1.11 1.24
Caloosahatchee 1 10 1.03 1.14 1.30
1 25 1.04 1.17 1.40
1 50 1.05 1.22 1.49
1 100 1.04 1.26 1.59
1 200 1.04 1.30 1.69
3 5 1.01 1.09 1.17
3 10 1.03 1.12 1.24
3 25 1.02 1.15 1.35
C-1
193
Rainfall Area Duration Return Period 25th Percentile 50th Percentile 75th Percentile
(days) (years)
3 50 1.02 1.19 1.43
3 100 1.02 1.22 1.54
3 200 1.02 1.26 1.64
7 5 0.98 1.05 1.14
7 10 0.99 1.07 1.19
7 25 0.99 1.11 1.30
7 50 0.98 1.15 1.38
7 100 0.97 1.20 1.49
7 200 0.96 1.24 1.60
East Everglades 1 5 1.00 1.10 1.21
Agricultural Area 1 10 1.01 1.13 1.27
1 25 1.01 1.16 1.36
1 50 1.01 1.19 1.43
1 100 1.01 1.21 1.51
1 200 1.00 1.23 1.59
3 5 1.00 1.09 1.17
3 10 1.00 1.11 1.23
3 25 1.01 1.15 1.32
3 50 1.01 1.17 1.39
3 100 1.00 1.19 1.47
3 200 0.99 1.22 1.56
7 5 0.99 1.06 1.13
7 10 1.00 1.09 1.19
7 25 1.00 1.13 1.28
7 50 0.99 1.16 1.36
7 100 0.99 1.18 1.45
7 200 0.98 1.21 1.55
Everglades 1 5 0.97 1.08 1.20
National Park 1 10 0.98 1.11 1.27
1 25 0.99 1.14 1.34
1 50 0.99 1.17 1.42
1 100 0.99 1.20 1.52
1 200 0.98 1.23 1.60
3 5 0.97 1.04 1.17
3 10 0.98 1.07 1.22
3 25 0.98 1.12 1.32
3 50 0.98 1.16 1.39
3 100 0.97 1.19 1.48
3 200 0.97 1.23 1.57
7 5 0.96 1.03 1.14
7 10 0.96 1.06 1.20
7 25 0.96 1.12 1.31
7 50 0.95 1.16 1.41
7 100 0.94 1.19 1.55
7 200 0.93 1.24 1.69
Florida Keys and 1 5 0.99 1.09 1.22
Biscayne Bay' 1 10 1.00 1.11 1.28
1 25 1.00 1.14 1.36
1 50 0.99 1.17 1.43
1 100 0.98 1.20 1.49
1 200 0.97 1.24 1.56
3 5 0.98 1.06 1.18
3 10 0.98 1.08 1.23
3 25 0.98 1.11 1.31
3 50 0.97 1.15 1.37
3 100 0.96 1.19 1.44
C-2
194
Rainfall Area Duration Return Period 25th Percentile 50th Percentile 75th Percentile
(days) (years)
3 200 0.95 1.22 1.52
7 5 0.97 1.04 1.15
7 10 0.97 1.07 1.20
7 25 0.96 1.11 1.27
7 50 0.95 1.13 1.36
7 100 0.94 1.17 1.46
7 200 0.92 1.19 1.57
Lake Okeechobee 1 5 1.02 1.11 1.22
1 10 1.02 1.13 1.27
1 25 1.01 1.16 1.34
1 50 1.00 1.19 1.40
1 100 1.00 1.20 1.47
1 200 0.98 1.23 1.55
3 5 1.01 1.09 1.17
3 10 1.02 1.12 1.23
3 25 1.02 1.15 1.31
3 50 1.01 1.18 1.38
3 100 1.00 1.20 1.45
3 200 0.99 1.22 1.53
7 5 0.99 1.06 1.15
7 10 1.00 1.09 1.20
7 25 1.00 1.13 1.30
7 50 0.99 1.17 1.39
7 100 0.98 1.20 1.47
7 200 0.97 1.24 1.58
Lower Kissimmee 1 5 1.04 1.13 1.22
1 10 1.05 1.16 1.28
1 25 1.05 1.19 1.37
1 50 1.05 1.22 1.44
1 100 1.05 1.25 1.52
1 200 1.04 1.28 1.62
3 5 1.03 1.11 1.19
3 10 1.03 1.14 1.25
3 25 1.04 1.18 1.34
3 50 1.04 1.22 1.42
3 100 1.04 1.26 1.52
3 200 1.04 1.30 1.62
7 5 1.00 1.08 1.17
7 10 1.01 1.12 1.22
7 25 1.03 1.17 1.33
7 50 1.03 1.22 1.42
7 100 1.04 1.26 1.53
7 200 1.03 1.31 1.65
Martin and St. 1 5 1.02 1.11 1.21
Lucie 1 10 1.02 1.13 1.25
1 25 1.02 1.15 1.31
1 50 1.01 1.18 1.37
1 100 1.01 1.20 1.43
1 200 0.99 1.22 1.49
3 5 1.01 1.10 1.18
3 10 1.02 1.12 1.23
3 25 1.02 1.15 1.30
3 50 1.01 1.17 1.36
3 100 1.01 1.20 1.44
3 200 0.99 1.21 1.52
7 5 1.01 1.08 1.16
C-3
195
Rainfall Area Duration Return Period 25th Percentile 50th Percentile 75th Percentile
(days) (years)
7 10 1.01 1.12 1.21
7 25 1.01 1.15 1.30
7 50 1.00 1.17 1.37
7 100 0.99 1.20 1.47
7 200 0.98 1.23 1.57
Miami-Dade 1 5 1.00 1.10 1.21
1 10 1.00 1.12 1.26
1 25 1.00 1.16 1.33
1 50 0.99 1.18 1.38
1 100 0.98 1.21 1.46
1 200 0.98 1.23 1.54
3 5 0.99 1.07 1.19
3 10 0.99 1.10 1.24
3 25 0.99 1.15 1.32
3 50 0.99 1.18 1.40
3 100 0.99 1.21 1.48
3 200 0.98 1.25 1.55
7 5 0.98 1.05 1.16
7 10 0.99 1.09 1.23
7 25 0.99 1.15 1.32
7 50 0.99 1.19 1.42
7 100 0.99 1.22 1.54
7 200 0.98 1.27 1.67
Palm Beach 1 5 1.01 1.11 1.20
1 10 1.02 1.14 1.27
1 25 1.02 1.17 1.36
1 50 1.01 1.20 1.44
1 100 1.01 1.22 1.51
1 200 1.00 1.25 1.60
3 5 1.01 1.09 1.19
3 10 1.01 1.12 1.25
3 25 1.01 1.15 1.35
3 50 1.02 1.19 1.41
3 100 1.01 1.22 1.50
3 200 1.01 1.25 1.60
7 5 1.00 1.07 1.17
7 10 1.01 1.09 1.22
7 25 0.99 1.13 1.33
7 50 0.98 1.17 1.40
7 100 0.97 1.20 1.49
7 200 0.96 1.24 1.59
Southwest Coast 1 5 1.02 1.12 1.22
1 10 1.03 1.15 1.29
1 25 1.03 1.18 1.40
1 50 1.03 1.23 1.50
1 100 1.02 1.27 1.62
1 200 1.01 1.32 1.75
3 5 1.00 1.08 1.17
3 10 1.01 1.12 1.24
3 25 1.01 1.16 1.34
3 50 1.01 1.21 1.45
3 100 1.00 1.25 1.56
3 200 0.99 1.30 1.68
7 5 0.97 1.05 1.13
7 10 0.98 1.08 1.18
7 25 0.98 1.13 1.29
C-4
196