SANTA ROSA COUNTY, FLORIDA - Northwest Florida Water ...portal.nwfwmdfloodmaps.com/.../SantaRosa_FIS.pdf · SANTA ROSA COUNTY, UNINCORPORATED AREAS 120274 : Revised Preliminary: July

VOLUME 1 OF 1

SANTA ROSA COUNTY, FLORIDA AND INCORPORATED AREAS COMMUNITY NAME COMMUNITY NUMBER GULF BREEZE, CITY OF 120275 JAY, TOWN OF 120339 MILTON, CITY OF 120276 SANTA ROSA COUNTY, UNINCORPORATED AREAS 120274

Revised Preliminary: July 29, 2019

REVISED: TBD

FLOOD INSURANCE STUDY NUMBER 12113CV000B Version Number 1.3.1.2

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TABLE OF CONTENTS Volume 1

Page

SECTION 1.0 – INTRODUCTION 1 1.1 The National Flood Insurance Program 1 1.2 Purpose of this Flood Insurance Study Report 2 1.3 Jurisdictions Included in the Flood Insurance Study Project 2 1.4 Considerations for using this Flood Insurance Study Report 5

SECTION 2.0 – FLOODPLAIN MANAGEMENT APPLICATIONS 15 2.1 Floodplain Boundaries 15 2.2 Floodways 21 2.3 Base Flood Elevations 22 2.4 Non-Encroachment Zones 22 2.5 Coastal Flood Hazard Areas 23

2.5.1 Water Elevations and the Effects of Waves 23 2.5.2 Floodplain Boundaries and BFEs for Coastal Areas 24 2.5.3 Coastal High Hazard Areas 25 2.5.4 Limit of Moderate Wave Action 26

SECTION 3.0 – INSURANCE APPLICATIONS 27 3.1 National Flood Insurance Program Insurance Zones 27 3.2 Coastal Barrier Resources System 27

SECTION 4.0 – AREA STUDIED 29 4.1 Basin Description 29 4.2 Principal Flood Problems 29 4.3 Non-Levee Flood Protection Measures 30 4.4 Levees 31

SECTION 5.0 – ENGINEERING METHODS 31 5.1 Hydrologic Analyses 32 5.2 Hydraulic Analyses 49 5.3 Coastal Analyses 55

5.3.1 Total Stillwater Elevations 56 5.3.2 Waves 58 5.3.3 Coastal Erosion 58 5.3.4 Wave Hazard Analyses 58

5.4 Alluvial Fan Analyses 77

SECTION 6.0 – MAPPING METHODS 77 6.1 Vertical and Horizontal Control 77 6.2 Base Map 78 6.3 Floodplain and Floodway Delineation 79 6.4 Coastal Flood Hazard Mapping 114 6.5 FIRM Revisions 119

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6.5.1 Letters of Map Amendment 119 6.5.2 Letters of Map Revision Based on Fill 119 6.5.3 Letters of Map Revision 120 6.5.4 Physical Map Revisions 120 6.5.5 Contracted Restudies 120 6.5.6 Community Map History 121

SECTION 7.0 – CONTRACTED STUDIES AND COMMUNITY COORDINATION 122 7.1 Contracted Studies 122 7.2 Community Meetings 124

SECTION 8.0 – ADDITIONAL INFORMATION 126

SECTION 9.0 – BIBLIOGRAPHY AND REFERENCES 127

Figures Page

Figure 1: FIRM Panel Index 7 Figure 2: FIRM Notes to Users 8 Figure 3: Map Legend for FIRM 11 Figure 4: Floodway Schematic 21 Figure 5: Wave Runup Transect Schematic 24 Figure 6: Coastal Transect Schematic 26 Figure 7: Frequency Discharge-Drainage Area Curves 38 Figure 8: 1% Annual Chance Total Stillwater Elevations for Coastal Areas 57 Figure 9: Transect Location Map 76

Tables Page

Table 1: Listing of NFIP Jurisdictions 2 Table 2: Flooding Sources Included in this FIS Report 16 Table 3: Flood Zone Designations by Community 27 Table 4: Coastal Barrier Resources System Information 28 Table 5: Basin Characteristics 29 Table 6: Principal Flood Problems 30 Table 7: Historic Flooding Elevations 30 Table 8: Non-Levee Flood Protection Measures 31 Table 9: Levees 31 Table 10: Summary of Discharges 33 Table 11: Summary of Non-Coastal Stillwater Elevations 38 Table 12: Stream Gage Information used to Determine Discharges 49 Table 13: Summary of Hydrologic and Hydraulic Analyses 50 Table 14: Roughness Coefficients 55 Table 15: Summary of Coastal Analyses 56

iii

Table 16: Tide Gage Analysis Specifics 57 Table 17: Coastal Transect Parameters 60 Table 18: Summary of Alluvial Fan Analyses 77 Table 19: Results of Alluvial Fan Analyses 77 Table 20: Countywide Vertical Datum Conversion 78 Table 21: Stream-Based Vertical Datum Conversion 78 Table 22: Base Map Sources 78 Table 23: Summary of Topographic Elevation Data used in Mapping 79 Table 24: Floodway Data 81 Table 25: Flood Hazard and Non-Encroachment Data for Selected Streams 89 Table 26: Summary of Coastal Transect Mapping Considerations 115 Table 27: Incorporated Letters of Map Change 120 Table 28: Community Map History 122 Table 29: Summary of Contracted Studies Included in this FIS Report 122 Table 30: Community Meetings 125 Table 31: Map Repositories 126 Table 32: Additional Information 127 Table 33: Bibliography and References 128

Volume 1 Exhibits

Flood Profiles Panel Blackwater River 01-07 PEast Bay River 08 PEscambia River 09-13 PPace Mill Creek 14-15 PPond Creek 16-18 PYellow River 19-20 P

Published Separately

Flood Insurance Rate Map (FIRM)

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FLOOD INSURANCE STUDY REPORT SANTA ROSA COUNTY, FLORIDA

SECTION 1.0 – INTRODUCTION

1.1 The National Flood Insurance Program The National Flood Insurance Program (NFIP) is a voluntary Federal program that enables property owners in participating communities to purchase insurance protection against losses from flooding. This insurance is designed to provide an alternative to disaster assistance to meet the escalating costs of repairing damage to buildings and their contents caused by floods. For decades, the national response to flood disasters was generally limited to constructing flood-control works such as dams, levees, sea-walls, and the like, and providing disaster relief to flood victims. This approach did not reduce losses nor did it discourage unwise development. In some instances, it may have actually encouraged additional development. To compound the problem, the public generally could not buy flood coverage from insurance companies, and building techniques to reduce flood damage were often overlooked. In the face of mounting flood losses and escalating costs of disaster relief to the general taxpayers, the U.S. Congress created the NFIP. The intent was to reduce future flood damage through community floodplain management ordinances, and provide protection for property owners against potential losses through an insurance mechanism that requires a premium to be paid for the protection. The U.S. Congress established the NFIP on August 1, 1968, with the passage of the National Flood Insurance Act of 1968. The NFIP was broadened and modified with the passage of the Flood Disaster Protection Act of 1973 and other legislative measures. It was further modified by the National Flood Insurance Reform Act of 1994 and the Flood Insurance Reform Act of 2004. The NFIP is administered by the Federal Emergency Management Agency (FEMA), which is a component of the Department of Homeland Security (DHS). Participation in the NFIP is based on an agreement between local communities and the Federal Government. If a community adopts and enforces floodplain management regulations to reduce future flood risks to new construction and substantially improved structures in Special Flood Hazard Areas (SFHAs), the Federal Government will make flood insurance available within the community as a financial protection against flood losses. The community’s floodplain management regulations must meet or exceed criteria established in accordance with Title 44 Code of Federal Regulations (CFR) Part 60.3, Criteria for Land Management and Use. SFHAs are delineated on the community’s Flood Insurance Rate Maps (FIRMs). Under the NFIP, buildings that were built before the flood hazard was identified on the community’s FIRMs are generally referred to as “Pre-FIRM” buildings. When the NFIP was created, the U.S. Congress recognized that insurance for Pre-FIRM buildings would be prohibitively expensive if the premiums were not subsidized by the Federal Government. Congress also recognized that most of these floodprone buildings were built by individuals who did not have sufficient knowledge of the flood hazard to make informed decisions. The NFIP requires that full actuarial rates reflecting the complete flood risk be charged on all buildings constructed or substantially improved on or after

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the effective date of the initial FIRM for the community or after December 31, 1974, whichever is later. These buildings are generally referred to as “Post-FIRM” buildings.

1.2 Purpose of this Flood Insurance Study Report This Flood Insurance Study (FIS) Report revises and updates information on the existence and severity of flood hazards for the study area. The studies described in this report developed flood hazard data that will be used to establish actuarial flood insurance rates and to assist communities in efforts to implement sound floodplain management. In some states or communities, floodplain management criteria or regulations may exist that are more restrictive than the minimum Federal requirements. Contact your State NFIP Coordinator to ensure that any higher State standards are included in the community’s regulations.

1.3 Jurisdictions Included in the Flood Insurance Study Project This FIS Report covers the entire geographic area of Santa Rosa County, Florida. The jurisdictions that are included in this project area, along with the Community Identification Number (CID) for each community and the 8-digit Hydrologic Unit Codes (HUC-8) sub-basins affecting each, are shown in Table 1. The Flood Insurance Rate Map (FIRM) panel numbers that affect each community are listed. If the flood hazard data for the community is not included in this FIS Report, the location of that data is identified.

Table 1: Listing of NFIP Jurisdictions

Community CID

HUC-8 Sub-

Basin(s) Located on FIRM Panel(s)

If Not Included,

Location of Flood Hazard

Data

Gulf Breeze, City of 120275 03140105

12113C0518H1

12113C0538H 12113C0606H 12113C0608H

12113C0519H 12113C0602H 12113C0607H 12113C0626H

Jay, Town of 120339

03140104 03140304 03140305

12113C0035H

Milton, City of 120276 03140104 12113C0314G1 12113C0427H 12113C0435H

12113C0320H 12113C0431H

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Community CID

HUC-8 Sub-


If Not Included,


Data Santa Rosa County, Unincorporated Areas

120274

03140103 03140104 03140105 03140304 03140305

12113C0010G 12113C0030H 12113C0040G 12113C0055H 12113C0065H 12113C0080H 12113C0090G 12113C0105H 12113C0115G 12113C0130G 12113C0140G 12113C0155H 12113C0165H 12113C0180H 12113C0190H 12113C0205H 12113C0215H 12113C0230G 12113C0240G 12113C0255G 12113C0270H 12113C0285H 12113C0291G1

12113C0293H 12113C0305H 12113C0311H 12113C0313H 12113C0320H 12113C0335H 12113C0355H 12113C0360H 12113C0370H 12113C0405H 12113C0408H 12113C0415H 12113C0420H 12113C0427H

12113C0020G 12113C0035H 12113C0045H 12113C0060H 12113C0070H 12113C0085H 12113C0095G 12113C0110H 12113C0120G 12113C0135G 12113C0145G 12113C0160H 12113C0170H 12113C0185H 12113C0195H 12113C0210G 12113C0220G 12113C0235H 12113C0245H 12113C0260G 12113C0280G 12113C0290H 12113C0292H 12113C0294H 12113C0310H 12113C0312G1

12113C0314G1

12113C0330H 12113C0340H 12113C0345H 12113C0365H 12113C0385H 12113C0406H 12113C0410H 12113C0426H 12113C0428G1

12113C0431H

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Community CID

HUC-8 Sub-


If Not Included,


Data Santa Rosa County, Unincorporated Areas

120274

03140103 03140104 03140105 03140304 03140305

12113C0429G1

12113C0435H 12113C0445H 12113C0460H 12113C0470H 12113C0485H 12113C0495H 12113C0513G1

12113C0517G1

12113C0519H 12113C0527H 12113C0529H 12113C0532H 12113C0534G1

12113C0537H

12113C0539H 12113C0542H 12113C0544H 12113C0552H 12113C0554H 12113C0560H 12113C0562H 12113C0564H 12113C0569H 12113C0580H 12113C0586H 12113C0588H 12113C0591H 12113C0601G1

12113C0603G1

12113C0606H 12113C0608H 12113C0627H 12113C0632G1

12113C0656H

12113C0440H 12113C0455H 12113C0465H 12113C0480H 12113C0490H 12113C0510G1

12113C0514G1

12113C0518H1

12113C0526H 12113C0528H 12113C0531H 12113C0533G1

12113C0536H1

12113C0538H 12113C0541G1

12113C0543H 12113C0551H 12113C0553G1

12113C0558H 12113C0561H 12113C0563H 12113C0568H 12113C0570H 12113C0585H 12113C0587H 12113C0589H 12113C0593H 12113C0602H 12113C0604H1

12113C0607H 12113C0626H 12113C0631G1

12113C0651G1

12113C0657H

1 Panel Not Printed

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1.4 Considerations for using this Flood Insurance Study Report The NFIP encourages State and local governments to implement sound floodplain management programs. To assist in this endeavor, each FIS Report provides floodplain data, which may include a combination of the following: 10-, 4-, 2-, 1-, and 0.2-percent annual chance flood elevations (the 1% annual chance flood elevation is also referred to as the Base Flood Elevation (BFE)); delineations of the 1% annual chance and 0.2% annual chance floodplains; and 1% annual chance floodway. This information is presented on the FIRM and/or in many components of the FIS Report, including Flood Profiles, Floodway Data tables, Summary of Non-Coastal Stillwater Elevations tables, and Coastal Transect Parameters tables (not all components may be provided for a specific FIS). This section presents important considerations for using the information contained in this FIS Report and the FIRM, including changes in format and content. Figures 1, 2, and 3 present information that applies to using the FIRM with the FIS Report.

• Part or all of this FIS Report may be revised and republished at any time. In addition, part of this FIS Report may be revised by a Letter of Map Revision (LOMR), which does not involve republication or redistribution of the FIS Report. Refer to Section 6.5 of this FIS Report for information about the process to revise the FIS Report and/or FIRM.

It is, therefore, the responsibility of the user to consult with community officials by contacting the community repository to obtain the most current FIS Report components. Communities participating in the NFIP have established repositories of flood hazard data for floodplain management and flood insurance purposes. Community map repository addresses are provided in Table 31, “Map Repositories,” within this FIS Report.

• New FIS Reports are frequently developed for multiple communities, such as entire counties. A countywide FIS Report incorporates previous FIS Reports for individual communities and the unincorporated area of the county (if not jurisdictional) into a single document and supersedes those documents for the purposes of the NFIP.

The initial Countywide FIS Report for Santa Rosa County became effective on December 19, 2006. Refer to Table 28 for information about subsequent revisions to the FIRMs.

• FEMA does not impose floodplain management requirements or special insurance ratings based on Limit of Moderate Wave Action (LiMWA) delineations at this time. The LiMWA represents the approximate landward limit of the 1.5-foot breaking wave. If the LiMWA is shown on the FIRM, it is being provided by FEMA as information only. For communities that do adopt Zone VE building standards in the area defined by the LiMWA, additional Community Rating System (CRS) credits are available. Refer to Section 2.5.4 for additional information about the LiMWA.

The CRS is a voluntary incentive program that recognizes and encourages community floodplain management activities that exceed the minimum NFIP requirements. Visit the FEMA Web site at www.fema.gov/national-flood-insurance-program-community-rating-system or contact your appropriate FEMA Regional Office for more information about this program.

http://www.fema.gov/national-flood-insurance-program-community-rating-system

http://www.fema.gov/national-flood-insurance-program-community-rating-system

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• Previous FIS Reports and FIRMs may have included levees that were accredited as reducing the risk associated with the 1% annual chance flood based on the information available and the mapping standards of the NFIP at that time. For FEMA to continue to accredit the identified levees, the levees must meet the criteria of the Code of Federal Regulations, Title 44, Section 65.10 (44 CFR 65.10), titled “Mapping of Areas Protected by Levee Systems.”

Since the status of levees is subject to change at any time, the user should contact the appropriate agency for the latest information regarding levees presented in Table 9 of this FIS Report. For levees owned or operated by the U.S. Army Corps of Engineers (USACE), information may be obtained from the USACE National Levee Database (nld.usace.army.mil). For all other levees, the user is encouraged to contact the appropriate local community.

• FEMA has developed a Guide to Flood Maps (FEMA 258) and online tutorials to assist users in accessing the information contained on the FIRM. These include how to read panels and step-by-step instructions to obtain specific information. To obtain this guide and other assistance in using the FIRM, visit the FEMA Web site at www.fema.gov/online-tutorials.

The FIRM Index in Figure 1 shows the overall FIRM panel layout within Santa Rosa County, and also displays the panel number and effective date for each FIRM panel in the county. Other information shown on the FIRM Index includes community boundaries, flooding sources, watershed boundaries, and United States Geological Survey (USGS) Hydrologic Unit Code – 8 (HUC-8) codes.

http://nld.usace.army.mil/

http://www.fema.gov/online-tutorials

NATIONAL FLOOD INSURANCE PROGRAMFLOOD INSURANCE RATE MAP INDEX

MAP NUMBER

FEMAHTTP://MSC.FEMA.GOVTHE INFORMATION DEPICTED ON THIS MAP AND SUPPORTINGDOCUMENTATION ARE ALSO AVAILABLE IN DIGITAL FORMAT AT

Map Projection:

SEE FLOOD INSURANCE STUDY FOR ADDITIONAL INFORMATION

COUNTY LOCATOR

SANTA ROSA COUNTY120274

CITY OF MILTON120276

CITY OF GULF BREEZE120275

TOWN OF JAY120339

ESCAMBIA COUNTY(AREA NOT INCLUDED)

¥¥10

£¤90

£¤98

¬«87

¬«89

¬«4

¬«87

¬«281

¬«87

Pond

Cree

k

East Bay

Escambia River

Santa Rosa Sound

Yellow River

Blackwater River

Moore Creek

Clear Creek

Escambia Bay

Sweet

water

Creek

Juniper Creek

Pensacola Bay

Dixon

Creek

Blackwater Bay

Gulf Of Mexico

Mann

ing C

reek

West

Fork

Big C

oldwa

ter Cr

eek

Big Coldwater Creek

Ates Creek

Long Branch

Turke

y Cree

k

Wolfe

Creek

Alliga

tor C

reek

Boiling Creek

Cobb Branch

Ready Creek

Mcdavid Creek

East Bay River

Malloy Branch

White River

Danle

y Bran

ch

Panther Creek

Weaver Creek

Pace Mill Creek

Wolf Creek

Pittman Creek

Bear Creek

Big Ju

niper

Creek

Crooked Creek

Buffalo M

ill Cree

kThomas

Creek

Weaver River

Dean Creek

Sevenmile Creek

Dead

River

Simpson River

Mulatto Bayou

0604H* 0608H12/19/20060603G*

0607H12/19/20060602H

12/19/2006 0651G* 0656H12/19/2006

0626H12/19/2006

0627H12/19/2006

0606H12/19/2006 0657H

12/19/20060631G*

0601G*0632G*

0514G* 0563H12/19/2006

0588H12/19/2006

0519H12/19/2006 0568H

12/19/20060539H

12/19/2006 0564H12/19/2006

0538H12/19/2006 0569H

12/19/20060518H*

0589H12/19/2006

0543H12/19/2006

0513G*

0593H12/19/2006

0544H12/19/2006

0536H* 0561H12/19/2006

0537H12/19/2006 0586H

12/19/20060517G* 0562H

12/19/20060541G* 0587H

12/19/20060542H

12/19/2006

0591H12/19/2006

0529H12/19/2006 0553G*

0528H12/19/2006 0558H

12/19/20060554H

12/19/20060533G* 0534G*

0526H12/19/2006 0551H

12/19/20060527H

12/19/2006 0552H12/19/2006

0531H12/19/2006

0532H12/19/2006

0429G**0428G**0408H12/19/2006

0406H12/19/2006 0426H

12/19/20060427H

12/19/20060431H

12/19/2006

0314G**0293H12/19/2006 0313H

12/19/20060294H

12/19/2006

0292H12/19/2006

0311H12/19/2006

0291G** 0312G**

0510G12/19/2006 0580H

12/19/20060585H

12/19/2006

0465H12/19/2006

0440H12/19/2006

0420H12/19/2006 0470H

12/19/20060490H

12/19/2006

0415H12/19/2006 0495H

12/19/20060445H

12/19/2006

0460H12/19/2006

0455H12/19/2006 0480H

12/19/2006

0405H12/19/2006

0385H12/19/2006 0485H

12/19/2006

0340H12/19/2006

0345H12/19/2006

0365H12/19/2006

0290H12/19/2006

0270H12/19/2006 0370H

12/19/20060320H

12/19/2006

0335H12/19/2006

0255G12/19/2006 0305H

12/19/2006 0330H12/19/2006

0285H12/19/2006 0355H

12/19/2006

0280G12/19/2006

0260G12/19/2006 0360H

12/19/20060310H

12/19/2006

0170H12/19/2006

0190H12/19/2006

0140G12/19/2006

0215H12/19/2006

0220G12/19/20060165H

12/19/2006 0240G12/19/2006

0245H12/19/2006

0145G12/19/2006 0195H

12/19/2006

0180H12/19/2006 0205H

12/19/2006

0130G12/19/2006 0210G

12/19/20060160H

12/19/2006 0230G12/19/2006

0155H12/19/2006

0135G12/19/2006 0235H

12/19/20060185H

12/19/2006

0090G12/19/2006

0065H12/19/2006

0045H12/19/2006 0095G

12/19/20060115G

12/19/2006

0040G12/19/2006 0120G

12/19/2006

0020G12/19/2006 0070H

12/19/2006

0085H12/19/2006

0055H12/19/2006

0035H12/19/2006 0080H

12/19/20060030H

12/19/2006 0105H12/19/2006

0110H12/19/2006

0010G12/19/2006 0060H

12/19/2006

0560H12/19/2006

0435H12/19/2006

0570H12/19/2006

0410H12/19/2006

HUC8 03140103Yellow

Watershed

HUC8 03140104BlackwaterWatershed

HUC8 03140105Pensacola Bay

Watershed

HUC8 03140305Escambia Watershed

HUC8 03140304Lower Conecuh

Watershed

1 in = 4 miles

0 1.5 3 4.5 60.75Miles

12113CIND0BMAP REVISED

0010, 0020, 0030, 0035, 0040, 0045, 0055, 0060, 0065, 0070, 0080, 0085, 0090, 0095, 0105, 0110, 0115, 0120, 0130, 0135, 0140, 0145, 0155, 0160, 0165, 0170, 0180, 0185, 0190, 0195,0205, 0210, 0215, 0220, 0230, 0235, 0240, 0245, 0255, 0260, 0270, 0280, 0285, 0290, 0292, 0293, 0294, 0305, 0310, 0311, 0313, 0320, 0330, 0335, 0340, 0345, 0355, 0360, 0365, 0370, 0385, 0405, 0406, 0408, 0410, 0415, 0420, 0426, 0427, 0431, 0435, 0440, 0445, 0455, 0460, 0465, 0470, 0480, 0485, 0490, 0495, 0519, 0526, 0527, 0528, 0529, 0531, 0532, 0537, 0538, 0539, 0542, 0543, 0544, 0551, 0552, 0554, 0558, 0560, 0561, 0562, 0563, 0564, 0568, 0569, 0570, 0580, 0585, 0586, 0587, 0588, 0589, 0591, 0593, 0602, 0606, 0607, 0608, 0626, 0627, 0656, 0657 *PANEL NOT PRINTED - OPEN WATER AREA

**PANEL NOT PRINTED - NO SPECIAL FLOOD HAZARD AREAS

and Incorporated AreasSANTA ROSA COUNTY, FLORIDAPANELS PRINTED: Florida State Plane North Zone (FIPS Zone 0903);

North American Datum 1983 HARN

Revised PreliminaryJuly 29, 2019

ATTENTION: The corporate limits shown on this FIRM Index are based on the best information available at the time of publication. As such, they may be more current than those shown on FIRM panels issued before December 19, 2016.

8

Each FIRM panel may contain specific notes to the user that provide additional information regarding the flood hazard data shown on that map. However, the FIRM panel does not contain enough space to show all the notes that may be relevant in helping to better understand the information on the panel. Figure 2 contains the full list of these notes.

Figure 2: FIRM Notes to Users

NOTES TO USERS For information and questions about this map, available products associated with this FIRM including historic versions of this FIRM, how to order products, or the National Flood Insurance Program in general, please call the FEMA Map Information eXchange at 1-877-FEMA-MAP (1-877-336-2627) or visit the FEMA Flood Map Service Center website at msc.fema.gov. Available products may include previously issued Letters of Map Change, a Flood Insurance Study Report, and/or digital versions of this map. Many of these products can be ordered or obtained directly from the website. Users may determine the current map date for each FIRM panel by visiting the FEMA Flood Map Service Center website or by calling the FEMA Map Information eXchange. Communities annexing land on adjacent FIRM panels must obtain a current copy of the adjacent panel as well as the current FIRM Index. These may be ordered directly from the Flood Map Service Center at the number listed above. For community and countywide map dates, refer to Table 28 in this FIS Report. To determine if flood insurance is available in the community, contact your insurance agent or call the National Flood Insurance Program at 1-800-638-6620. PRELIMINARY FIS REPORT: FEMA maintains information about map features, such as street locations and names, in or near designated flood hazard areas. Requests to revise information in or near designated flood hazard areas may be provided to FEMA during the community review period, at the final Consultation Coordination Officer's meeting, or during the statutory 90-day appeal period. Approved requests for changes will be shown on the final printed FIRM.

The map is for use in administering the NFIP. It may not identify all areas subject to flooding, particularly from local drainage sources of small size. Consult the community map repository to find updated or additional flood hazard information. BASE FLOOD ELEVATIONS: For more detailed information in areas where Base Flood Elevations (BFEs) and/or floodways have been determined, consult the Flood Profiles and Floodway Data and/or Summary of Non-Coastal Stillwater Elevations tables within this FIS Report. Use the flood elevation data within the FIS Report in conjunction with the FIRM for construction and/or floodplain management. Coastal Base Flood Elevations shown on the map apply only landward of 0.0' North American Vertical Datum of 1988 (NAVD88). Coastal flood elevations are also provided in the Coastal Transect Parameters table in the FIS Report for this jurisdiction. Elevations shown in the Coastal Transect Parameters table should be used for construction and/or floodplain management purposes when they are higher than the elevations shown on the FIRM.

http://msc.fema.gov/


9

FLOODWAY INFORMATION: Boundaries of the floodways were computed at cross sections and interpolated between cross sections. The floodways were based on hydraulic considerations with regard to requirements of the National Flood Insurance Program. Floodway widths and other pertinent floodway data are provided in the FIS Report for this jurisdiction. FLOOD CONTROL STRUCTURE INFORMATION: Certain areas not in Special Flood Hazard Areas may be protected by flood control structures. Refer to Section 4.3 "Non-Levee Flood Protection Measures" of this FIS Report for information on flood control structures for this jurisdiction. PROJECTION INFORMATION: The projection used in the preparation of the map was Florida State Plane North Zone (FIPS Zone 0903), North American Datum of 1983 (NAD83). The horizontal datum was NAD83. Differences in datum, spheroid, projection or State Plane zones used in the production of FIRMs for adjacent jurisdictions may result in slight positional differences in map features across jurisdiction boundaries. These differences do not affect the accuracy of the FIRM. ELEVATION DATUM: Flood elevations on the FIRM are referenced to the North American Vertical Datum of 1988. These flood elevations must be compared to structure and ground elevations referenced to the same vertical datum. For information regarding conversion between the National Geodetic Vertical Datum of 1929 and the North American Vertical Datum of 1988, visit the National Geodetic Survey website at www.ngs.noaa.gov/ or contact the National Geodetic Survey at the following address: NGS Information Services NOAA, N/NGS12 National Geodetic Survey SSMC-3, #9202 1315 East-West Highway Silver Spring, Maryland 20910-3282 (301) 713-3242 Local vertical monuments may have been used to create the map. To obtain current monument information, please contact the appropriate local community listed in Table 31 of this FIS Report. BASE MAP INFORMATION: Base map information shown on the FIRM was provided by Florida Department of Transportation (FDOT). This information was derived from digital orthophotography at a 0.9 foot resolution from photography dated 2013. For information about base maps, refer to Section 6.2 “Base Map” in this FIS Report. The map reflects more detailed and up-to-date stream channel configurations than those shown on the previous FIRM for this jurisdiction. The floodplains and floodways that were transferred from the previous FIRM may have been adjusted to conform to these new stream channel configurations. As a result, the Flood Profiles and Floodway Data tables may reflect stream channel distances that differ from what is shown on the map. Corporate limits shown on the map are based on the best data available at the time of publication. Because changes due to annexations or de-annexations may have occurred after the map was published, map users should contact appropriate community officials to verify current corporate limit locations.

http://www.ngs.noaa.gov/


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NOTES FOR FIRM INDEX REVISIONS TO INDEX: As new studies are performed and FIRM panels are updated within Santa Rosa County, FL, corresponding revisions to the FIRM Index will be incorporated within the FIS Report to reflect the effective dates of those panels. Please refer to Table 28 of this FIS Report to determine the most recent FIRM revision date for each community. The most recent FIRM panel effective date will correspond to the most recent index date. SPECIAL NOTES FOR SPECIFIC FIRM PANELS This Notes to Users section was created specifically for Santa Rosa County, FL, effective TBD. COASTAL BARRIER RESOURCES SYSTEM (CBRS): This map includes approximate boundaries of the CBRS for informational purposes only. Flood insurance is not available within CBRS areas for structures that are newly built or substantially improved on or after the date(s) indicated on the map. For more information see www.fws.gov/cbra/, the FIS Report, or call the U.S. Fish and Wildlife Service Customer Service Center at 1-800-344-WILD. LIMIT OF MODERATE WAVE ACTION: Zone AE has been divided by a Limit of Moderate Wave Action (LiMWA). The LiMWA represents the approximate landward limit of the 1.5-foot breaking wave. The effects of wave hazards between Zone VE and the LiMWA (or between the shoreline and the LiMWA for areas where Zone VE is not identified) will be similar to, but less severe than, those in Zone VE. FLOOD RISK REPORT: A Flood Risk Report (FRR) may be available for many of the flooding sources and communities referenced in this FIS Report. The FRR is provided to increase public awareness of flood risk by helping communities identify the areas within their jurisdictions that have the greatest risks. Although non-regulatory, the information provided within the FRR can assist communities in assessing and evaluating mitigation opportunities to reduce these risks. It can also be used by communities developing or updating flood risk mitigation plans. These plans allow communities to identify and evaluate opportunities to reduce potential loss of life and property. However, the FRR is not intended to be the final authoritative source of all flood risk data for a project area; rather, it should be used with other data sources to paint a comprehensive picture of flood risk.

http://www.fws.gov/cbra/

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Each FIRM panel contains an abbreviated legend for the features shown on the maps. However, the FIRM panel does not contain enough space to show the legend for all map features. Figure 3 shows the full legend of all map features. Note that not all of these features may appear on the FIRM panels in Santa Rosa County.

Figure 3: Map Legend for FIRM

SPECIAL FLOOD HAZARD AREAS: The 1% annual chance flood, also known as the base flood or 100-year flood, has a 1% chance of happening or being exceeded each year. Special Flood Hazard Areas are subject to flooding by the 1% annual chance flood. The Base Flood Elevation is the water surface elevation of the 1% annual chance flood. The floodway is the channel of a stream plus any adjacent floodplain areas that must be kept free of encroachment so that the 1% annual chance flood can be carried without substantial increases in flood heights. See note for specific types. If the floodway is too narrow to be shown, a note is shown.

Special Flood Hazard Areas subject to inundation by the 1% annual chance flood (Zones A, AE, AH, AO, AR, A99, V and VE)

Zone A The flood insurance rate zone that corresponds to the 1% annual chance floodplains. No base (1% annual chance) flood elevations (BFEs) or depths are shown within this zone.

Zone AE The flood insurance rate zone that corresponds to the 1% annual chance floodplains. Base flood elevations derived from the hydraulic analyses are shown within this zone.

Zone AH The flood insurance rate zone that corresponds to the areas of 1% annual chance shallow flooding (usually areas of ponding) where average depths are between 1 and 3 feet. Whole-foot BFEs derived from the hydraulic analyses are shown at selected intervals within this zone.

Zone AO The flood insurance rate zone that corresponds to the areas of 1% annual chance shallow flooding (usually sheet flow on sloping terrain) where average depths are between 1 and 3 feet. Average whole-foot depths derived from the hydraulic analyses are shown within this zone.

Zone AR The flood insurance rate zone that corresponds to areas that were formerly protected from the 1% annual chance flood by a flood control system that was subsequently decertified. Zone AR indicates that the former flood control system is being restored to provide protection from the 1% annual chance or greater flood.

Zone A99 The flood insurance rate zone that corresponds to areas of the 1% annual chance floodplain that will be protected by a Federal flood protection system where construction has reached specified statutory milestones. No base flood elevations or flood depths are shown within this zone.

Zone V The flood insurance rate zone that corresponds to the 1% annual chance coastal floodplains that have additional hazards associated with storm waves. Base flood elevations are not shown within this zone.

Zone VE Zone VE is the flood insurance rate zone that corresponds to the 1% annual chance coastal floodplains that have additional hazards associated with storm waves. Base flood elevations derived from the coastal analyses are shown within this zone as static whole-foot elevations that apply throughout the zone.


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Regulatory Floodway determined in Zone AE.

Non-encroachment zone (see Section 2.4 of this FIS Report for more information)

FLOOD INSURANCE IS NOT AVAILABLE FOR STRUCTURES NEWLY BUILT OR SUBSTANTIALLY IMPROVED ON OR AFTER APRIL 8, 1987, IN THE DESIGNATED COLORADO RIVER FLOODWAY

The Colorado River Floodway was established by Congress in the Colorado River Floodway Protection Act of 1986, Public Law 99-450 (100 Statute 1129). The Act imposes certain restrictions within the Floodway.

OTHER AREAS OF FLOOD HAZARD

Shaded Zone X: Areas of 0.2% annual chance flood hazards and areas of 1% annual chance flood hazards with average depths of less than 1 foot or with drainage areas less than 1 square mile.

Future Conditions 1% Annual Chance Flood Hazard – Zone X: The flood insurance rate zone that corresponds to the 1% annual chance floodplains that are determined based on future-conditions hydrology. No base flood elevations or flood depths are shown within this zone.

Area with Reduced Flood Risk due to Levee: Areas where an accredited levee, dike, or other flood control structure has reduced the flood risk from the 1% annual chance flood. See Notes to Users for important information.

OTHER AREAS

Zone D (Areas of Undetermined Flood Hazard): The flood insurance rate zone that corresponds to unstudied areas where flood hazards are undetermined, but possible.

Unshaded Zone X: Areas of minimal flood hazard.

FLOOD HAZARD AND OTHER BOUNDARY LINES

(ortho) (vector)

Flood Zone Boundary (white line on ortho-photography-based mapping; gray line on vector-based mapping)

Limit of Study

Jurisdiction Boundary

Limit of Moderate Wave Action (LiMWA): Indicates the inland limit of the area affected by waves greater than 1.5 feet

NO SCREEN


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GENERAL STRUCTURES

Aqueduct Channel Culvert

Storm Sewer

Channel, Culvert, Aqueduct, or Storm Sewer

__________ Dam Jetty Weir

Dam, Jetty, Weir

Levee, Dike, or Floodwall

Bridge

Bridge

COASTAL BARRIER RESOURCES SYSTEM (CBRS) AND OTHERWISE PROTECTED AREAS (OPA): CBRS areas and OPAs are normally located within or adjacent to Special Flood Hazard Areas. See Notes to Users for important information.

CBRS AREA 09/30/2009

Coastal Barrier Resources System Area: Labels are shown to clarify where this area shares a boundary with an incorporated area or overlaps with the floodway.

OTHERWISE PROTECTED AREA

09/30/2009

Otherwise Protected Area

REFERENCE MARKERS

River mile Markers

CROSS SECTION & TRANSECT INFORMATION

Lettered Cross Section with Regulatory Water Surface Elevation (BFE)

Numbered Cross Section with Regulatory Water Surface Elevation (BFE)

Unlettered Cross Section with Regulatory Water Surface Elevation (BFE)

Coastal Transect


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Profile Baseline: Indicates the modeled flow path of a stream and is shown on FIRM panels for all valid studies with profiles or otherwise established base flood elevation.

Coastal Transect Baseline: Used in the coastal flood hazard model to represent the 0.0-foot elevation contour and the starting point for the transect and the measuring point for the coastal mapping.

Base Flood Elevation Line

ZONE AE (EL 16) Static Base Flood Elevation value (shown under zone label)

ZONE AO (DEPTH 2) Zone designation with Depth

ZONE AO (DEPTH 2)

(VEL 15 FPS) Zone designation with Depth and Velocity

BASE MAP FEATURES

Missouri Creek River, Stream or Other Hydrographic Feature

Interstate Highway

U.S. Highway

State Highway

County Highway

MAPLE LANE

Street, Road, Avenue Name, or Private Drive if shown on Flood Profile

RAILROAD

Railroad

Horizontal Reference Grid Line

Horizontal Reference Grid Ticks

Secondary Grid Crosshairs

Land Grant Name of Land Grant

7 Section Number

R. 43 W. T. 22 N. Range, Township Number

4276000mE Horizontal Reference Grid Coordinates (UTM)

365000 FT Horizontal Reference Grid Coordinates (State Plane)

80° 16’ 52.5” Corner Coordinates (Latitude, Longitude)

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SECTION 2.0 – FLOODPLAIN MANAGEMENT APPLICATIONS

2.1 Floodplain Boundaries To provide a national standard without regional discrimination, the 1% annual chance (100-year) flood has been adopted by FEMA as the base flood for floodplain management purposes. The 0.2% annual chance (500-year) flood is employed to indicate additional areas of flood hazard in the community. Each flooding source included in the project scope has been studied and mapped using professional engineering and mapping methodologies that were agreed upon by FEMA and Santa Rosa County as appropriate to the risk level. Flood risk is evaluated based on factors such as known flood hazards and projected impact on the built environment. Engineering analyses were performed for each studied flooding source to calculate its 1% annual chance flood elevations; elevations corresponding to other floods (e.g. 10-, 4-, 2-, 0.2-percent annual chance, etc.) may have also been computed for certain flooding sources. Engineering models and methods are described in detail in Section 5.0 of this FIS Report. The modeled elevations at cross sections were used to delineate the floodplain boundaries on the FIRM; between cross sections, the boundaries were interpolated using elevation data from various sources. More information on specific mapping methods is provided in Section 6.0 of this FIS Report. Depending on the accuracy of available topographic data (Table 23), study methodologies employed (Section 5.0), and flood risk, certain flooding sources may be mapped to show both the 1% and 0.2% annual chance floodplain boundaries, regulatory water surface elevations (BFEs), and/or a regulatory floodway. Similarly, other flooding sources may be mapped to show only the 1% annual chance floodplain boundary on the FIRM, without published water surface elevations. In cases where the 1% and 0.2% annual chance floodplain boundaries are close together, only the 1% annual chance floodplain boundary is shown on the FIRM. Figure 3, “Map Legend for FIRM”, describes the flood zones that are used on the FIRMs to account for the varying levels of flood risk that exist along flooding sources within the project area. Table 2 and Table 3 indicate the flood zone designations for each flooding source and each community within Santa Rosa County, respectively.

Table 2, “Flooding Sources Included in this FIS Report,” lists each flooding source, including its study limits, affected communities, mapped zone on the FIRM, and the completion date of its engineering analysis from which the flood elevations on the FIRM and in the FIS Report were derived. Descriptions and dates for the latest hydrologic and hydraulic analyses of the flooding sources are shown in Table 13. Floodplain boundaries for these flooding sources are shown on the FIRM (published separately) using the symbology described in Figure 3. On the map, the 1% annual chance floodplain corresponds to the SFHAs. The 0.2% annual chance floodplain shows areas that, although out of the regulatory floodplain, are still subject to flood hazards. Small areas within the floodplain boundaries may lie above the flood elevations but cannot be shown due to limitations of the map scale and/or lack of detailed topographic data. The procedures to remove these areas from the SFHA are described in Section 6.5 of this FIS Report.

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Table 2: Flooding Sources Included in this FIS Report

Flooding Source Community Downstream

Limit Upstream Limit HUC-8 Sub-

Basin(s)

Length (mi) (streams or coastlines)

Area (mi2) (estuaries or

ponding) Floodway

(Y/N)

Zone shown on

FIRM Date of

Analysis

Beale Creek Santa Rosa County, Unincorporated Areas

At confluence Escambia River

Approximately 800 feet southwest of Curtis Road

03140305 3.8 N AE 2012

Big Coldwater Creek

Santa Rosa County, Unincorporated Areas

At confluence with Blackwater River

Approximately 0.65 miles northwest of Steel Bridge Road

03140104 7.4 N AE 2018

Big Coldwater Creek



At confluence with East Fork Big Coldwater Creek and West Fork Big Coldwater Creek

03140104 4.1 N AE 2012

Blackwater Bay Santa Rosa County, Unincorporated Areas Entire Coastline Entire Coastline 03140103

03140105 26.8 N AE, VE 2015

Blackwater River City of Milton, Santa Rosa County, Unincorporated Areas

At Interstate 10 Approximately 620 feet downstream Deaton Bridge Road

03140104 03140105 19.0 Y AE 2012

Blackwater River City of Milton, Santa Rosa County, Unincorporated Areas

Approximately 620 feet downstream Deaton Bridge Road

At County Boundary 03140104 03140105 14.6 N AE 2012

Bray Mill Creek Santa Rosa County, Unincorporated Areas, Town of Jay

At confluence with Escambia River

At Town of Jay Boundary

03140304 03140305 3.4 nN A 2012

Clear Creek Santa Rosa County, Unincorporated Areas


Just upstream of Blackwater Heritage State Trail

03140104 4.0 N AE 2018

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Basin(s)



ponding) Floodway

(Y/N)

Zone shown on

FIRM Date of

Analysis

Clear Creek Santa Rosa County, Unincorporated Areas


Approximately 1,400 feet southeast of Forrest Hills Rd

03140104 5.9 N AE 2012

East Bay Santa Rosa County, Unincorporated Areas Entire Coastline Entire Coastline 03140105 33.0 N AE, VE 2015

East Bay River Santa Rosa County, Unincorporated Areas

At confluence with East Bay At County Boundary 03140105 7.6 Y AE 1984

East Fork Big Coldwater Creek


At confluence with Big Coldwater Creek and West Fork Big Coldwater Creek

Approximately 0.5 miles east of Gordon Land Rd.

03140104 7.3 N AE 2012

Escambia Bay Santa Rosa County, Unincorporated Areas Entire Coastline Entire Coastline 03140105 25.5 N AE, VE 2015

Escambia River Santa Rosa County, Unincorporated Areas At US 10 Just upstream

Highway 4

03140105 03140304 03140305

51.4 Y AE 2005

Escambia River Santa Rosa County, Unincorporated Areas

Just upstream Highway 4

At Florida/Alabama state line

03140105 03140304 03140305

7.0 N A 2005

Gulf of Mexico Santa Rosa County, Unincorporated Areas Entire Coastline Entire Coastline 03140105 8.6 N AE, VE 2015

Holley by the Sea Santa Rosa County, Unincorporated Areas

Entire Watershed Entire Watershed 03140105 2.1 N AE 2016

Holley by the Sea Santa Rosa County, Unincorporated Areas

Entire Watershed Entire Watershed 03140105 2.1 N A 2016

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Basin(s)



ponding) Floodway

(Y/N)

Zone shown on

FIRM Date of

Analysis

Jacobs Creek Santa Rosa County, Unincorporated Areas

At confluence with Pace Mill Creek

At Becky Ln 03140105 1.0 N AE 2012

Juniper Creek Santa Rosa County, Unincorporated Areas

At confluence with West Fork Big Coldwater Creek

Approximately 630 feet south of Letcher Block Road

03140104 10.5 N AE 2012

Juniper Creek Santa Rosa County, Unincorporated Areas 03140104 N A 2012

Long Branch Santa Rosa County, Unincorporated Areas

At confluence with Pond Creek

At Long Branch Pond 03140104 2.7 N A 2012

Malloy Branch Santa Rosa County, Unincorporated Areas


At Town of Jay Boundary 03140104 5.3 N A 2012

Manning Creek Santa Rosa County, Unincorporated Areas


At Van Jernigan Road 03140104 5.4 N AE 2012

Pace Mill Creek Santa Rosa County, Unincorporated Areas

At confluence with Escambia Bay

At Chumuckla Hwy 03140105 03140305 5.3 Y AE 2005

Pensacola Bay City of Gulf Breeze, Santa Rosa County, Unincorporated Areas

Entire Coastline Entire Coastline 03140105 11.4 N AE, VE 2015

Pond Creek Santa Rosa County, Unincorporated Areas

At Willard Norris Road

Just upstream Fort Acre Pond 03140104 16.4 N AE 2012

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Basin(s)



ponding) Floodway

(Y/N)

Zone shown on

FIRM Date of

Analysis

Pond Creek City of Milton, Santa Rosa County, Unincorporated Areas


At Willard Norris Road 03140104 13.2 Y AE 2005

Reader Creek Santa Rosa County, Unincorporated Areas

At confluence with Pond Creek

At Fairway Drive 03140104 3.6 N AE 2012

Rocky Creek Santa Rosa County, Unincorporated Areas

At Confluence with Escambia River

At Rowe Trail 03140305 3.3 N AE 2012

Santa Rosa Sound

City of Gulf Breeze, Santa Rosa County, Unincorporated Areas

Entire Coastline Entire Coastline 03140105 36.2 N AE, VE 2015

Unnamed Tributary to Beale Creek



Approximately 300 feet north of Highway 4

03140305 1.0 N AE 2012

Unnamed Tributary to Bray Mill Creek


At confluence with Bray Mill Creek

Approximately 3,000 feet north of Highway 4

03140304 0.23 N A 2012

Unnamed Tributary to Escambia River


At confluence with Big Coldwater Creek and East Fork Big Coldwater Creek

Approximately 1,300 feet southwest of County Mill Road

03140305 2.6 N A 2012

20




Basin(s)



ponding) Floodway

(Y/N)

Zone shown on

FIRM Date of

Analysis

West Fork Big Coldwater Creek



Just upstream confluence with Juniper Creek

03140104 9.6 N AE 2012




At confluence with Malloy Branch 03140104 7.2 N A 2012

Yellow River Santa Rosa County, Unincorporated Areas



03140103 03140105 20.1 Y AE 2012

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2.2 Floodways Encroachment on floodplains, such as structures and fill, reduces flood-carrying capacity, increases flood heights and velocities, and increases flood hazards in areas beyond the encroachment itself. One aspect of floodplain management involves balancing the economic gain from floodplain development against the resulting increase in flood hazard. For purposes of the NFIP, a floodway is used as a tool to assist local communities in balancing floodplain development against increasing flood hazard. With this approach, the area of the 1% annual chance floodplain on a river is divided into a floodway and a floodway fringe based on hydraulic modeling. The floodway is the channel of a stream, plus any adjacent floodplain areas, that must be kept free of encroachment in order to carry the 1% annual chance flood. The floodway fringe is the area between the floodway and the 1% annual chance floodplain boundaries where encroachment is permitted. The floodway must be wide enough so that the floodway fringe could be completely obstructed without increasing the water surface elevation of the 1% annual chance flood more than 1 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in Figure 4. To participate in the NFIP, Federal regulations require communities to limit increases caused by encroachment to 1.0 foot, provided that hazardous velocities are not produced. The floodways in this project are presented to local agencies as minimum standards that can be adopted directly or that can be used as a basis for additional floodway projects.

Figure 4: Floodway Schematic

Floodway widths presented in this FIS Report and on the FIRM were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. For certain stream segments,

22

floodways were adjusted so that the amount of floodwaters conveyed on each side of the floodplain would be reduced equally. The results of the floodway computations have been tabulated for selected cross sections and are shown in Table 24, “Floodway Data.” All floodways that were developed for this Flood Risk Project are shown on the FIRM using the symbology described in Figure 3. In cases where the floodway and l% annual chance floodplain boundaries are either close together or collinear, only the floodway boundary has been shown on the FIRM. For information about the delineation of floodways on the FIRM, refer to Section 6.3.

2.3 Base Flood Elevations The hydraulic characteristics of flooding sources were analyzed to provide estimates of the elevations of floods of the selected recurrence intervals. The Base Flood Elevation (BFE) is the elevation of the 1% annual chance flood. These BFEs are most commonly rounded to the whole foot, as shown on the FIRM, but in certain circumstances or locations they may be rounded to 0.1 foot. Cross section lines shown on the FIRM may also be labeled with the BFE rounded to 0.1 foot. Whole-foot BFEs derived from engineering analyses that apply to coastal areas, areas of ponding, or other static areas with little elevation change may also be shown at selected intervals on the FIRM. Cross sections with BFEs shown on the FIRM correspond to the cross sections shown in the Floodway Data table and Flood Profiles in this FIS Report. BFEs are primarily intended for flood insurance rating purposes. For construction and/or floodplain management purposes, users are cautioned to use the flood elevation data presented in this FIS Report in conjunction with the data shown on the FIRM.

2.4 Non-Encroachment Zones Some States and communities use non-encroachment zones to manage floodplain development. For flooding sources with medium flood risk, field surveys are often not collected and surveyed bridge and culvert geometry is not developed. Standard hydrologic and hydraulic analyses are still performed to determine BFEs in these areas. However, floodways are not typically determined, since specific channel profiles are not developed. To assist communities with managing floodplain development in these areas, a “non-encroachment zone” may be provided. While not a FEMA designated floodway, the non-encroachment zone represents that area around the stream that should be reserved to convey the 1% annual chance flood event. As with a floodway, all surcharges must fall within the acceptable range in the non-encroachment zone. General setbacks can be used in areas of lower risk (e.g. unnumbered Zone A), but these are not considered sufficient where unnumbered Zone A is replaced by Zone AE. The NFIP requires communities to ensure that any development in a non-encroachment area causes no increase in BFEs. Communities must generally prohibit development within the area defined by the non-encroachment width to meet the NFIP requirement. Non-encroachment determinations may be delineated where it is not possible to delineate floodways because specific channel profiles with bridge and culvert geometry were not developed. Any non-encroachment determinations for this Flood Risk Project have been tabulated for selected cross sections and are shown in Table 25, “Flood Hazard and Non-Encroachment Data for Selected Streams.” Areas for which non-encroachment zones are provided show BFEs and the 1% annual chance floodplain boundaries mapped as zone AE on the FIRM but no floodways.

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2.5 Coastal Flood Hazard Areas For most areas along rivers, streams, and small lakes, BFEs and floodplain boundaries are based on the amount of water expected to enter the area during a 1% annual chance flood and the geometry of the floodplain. Floods in these areas are typically caused by storm events. However, for areas on or near ocean coasts, large rivers, or large bodies of water, BFE and floodplain boundaries may need to be based on additional components, including storm surges and waves. Communities on or near ocean coasts face flood hazards caused by offshore seismic events as well as storm events. Coastal flooding sources that are included in this Flood Risk Project are shown in Table 2.

2.5.1 Water Elevations and the Effects of Waves Specific terminology is used in coastal analyses to indicate which components have been included in evaluating flood hazards. The stillwater elevation (SWEL or still water level) is the surface of the water resulting from astronomical tides, storm surge, and freshwater inputs, but excluding wave setup contribution or the effects of waves.

• Astronomical tides are periodic rises and falls in large bodies of water caused by the rotation of the earth and by the gravitational forces exerted by the earth, moon and sun.

• Storm surge is the additional water depth that occurs during large storm events. These events can bring air pressure changes and strong winds that force water up against the shore.

• Freshwater inputs include rainfall that falls directly on the body of water, runoff from surfaces and overland flow, and inputs from rivers.

The 1% annual chance stillwater elevation is the stillwater elevation that has been calculated for a storm surge from a 1% annual chance storm. The 1% annual chance storm surge can be determined from analyses of tidal gage records, statistical study of regional historical storms, or other modeling approaches. Stillwater elevations for storms of other frequencies can be developed using similar approaches. The total stillwater elevation (also referred to as the mean water level) is the stillwater elevation plus wave setup contribution but excluding the effects of waves.

• Wave setup is the increase in stillwater elevation at the shoreline caused by the reduction of waves in shallow water. It occurs as breaking wave momentum is transferred to the water column.

Like the stillwater elevation, the total stillwater elevation is based on a storm of a particular frequency, such as the 1% annual chance storm. Wave setup is typically estimated using standard engineering practices or calculated using models, since tidal gages are often sited in areas sheltered from wave action and do not capture this information. Coastal analyses may examine the effects of overland waves by analyzing storm-induced erosion, overland wave propagation, wave runup, and/or wave overtopping.

• Storm-induced erosion is the modification of existing topography by erosion caused by a specific storm event, as opposed to general erosion that occurs at a more constant rate.

24

• Overland wave propagation describes the combined effects of variation in ground elevation, vegetation, and physical features on wave characteristics as waves move onshore.

• Wave runup is the uprush of water from wave action on a shore barrier. It is a function of the roughness and geometry of the shoreline at the point where the stillwater elevation intersects the land.

• Wave overtopping refers to wave runup that occurs when waves pass over the crest of a barrier.

Figure 5: Wave Runup Transect Schematic

2.5.2 Floodplain Boundaries and BFEs for Coastal Areas For coastal communities along the Atlantic and Pacific Oceans, the Gulf of Mexico, the Great Lakes, and the Caribbean Sea, flood hazards must take into account how storm surges, waves, and extreme tides interact with factors such as topography and vegetation. Storm surge and waves must also be considered in assessing flood risk for certain communities on rivers or large inland bodies of water. Beyond areas that are affected by waves and tides, coastal communities can also have riverine floodplains with designated floodways, as described in previous sections. Floodplain Boundaries In many coastal areas, storm surge is the principle component of flooding. The extent of the 1% annual chance floodplain in these areas is derived from the total stillwater elevation (stillwater elevation including storm surge plus wave setup) for the 1% annual chance storm. The methods that were used for calculation of total stillwater elevations for coastal areas are described in Section 5.3 of this FIS Report. Location of total stillwater elevations for coastal areas are shown in Figure 8, “1% Annual Chance Total Stillwater Levels for Coastal Areas.” In some areas, the 1% annual chance floodplain is determined based on the limit of wave runup or wave overtopping for the 1% annual chance storm surge. The methods that were used for calculation of wave hazards are described in Section 5.3 of this FIS Report.

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Table 26 presents the types of coastal analyses that were used in mapping the 1% annual chance floodplain in coastal areas. Coastal BFEs Coastal BFEs are calculated as the total stillwater elevation (stillwater elevation including storm surge plus wave setup) for the 1% annual chance storm plus the additional flood hazard from overland wave effects (storm-induced erosion, overland wave propagation, wave runup and wave overtopping). Where they apply, coastal BFEs are calculated along transects extending from offshore to the limit of coastal flooding onshore. Results of these analyses are accurate until local topography, vegetation, or development type and density within the community undergoes major changes. Parameters that were included in calculating coastal BFEs for each transect included in this FIS Report are presented in Table 17, “Coastal Transect Parameters.” The locations of transects are shown in Figure 9, “Transect Location Map.” More detailed information about the methods used in coastal analyses and the results of intermediate steps in the coastal analyses are presented in Section 5.3 of this FIS Report. Additional information on specific mapping methods is provided in Section 6.4 of this FIS Report.

2.5.3 Coastal High Hazard Areas Certain areas along the open coast and other areas may have higher risk of experiencing structural damage caused by wave action and/or high-velocity water during the 1% annual chance flood. These areas will be identified on the FIRM as Coastal High Hazard Areas.

• Coastal High Hazard Area (CHHA) is a SFHA extending from offshore to the inland limit of the primary frontal dune (PFD) or any other area subject to damages caused by wave action and/or high-velocity water during the 1% annual chance flood.

• Primary Frontal Dune (PFD) is a continuous or nearly continuous mound or ridge of sand with relatively steep slopes immediately landward and adjacent to the beach. The PFD is subject to erosion and overtopping from high tides and waves during major coastal storms.

CHHAs are designated as “V” zones (for “velocity wave zones”) and are subject to more stringent regulatory requirements and a different flood insurance rate structure. The areas of greatest risk are shown as VE on the FIRM. Zone VE is further subdivided into elevation zones and shown with BFEs on the FIRM. The landward limit of the PFD occurs at a point where there is a distinct change from a relatively steep slope to a relatively mild slope; this point represents the landward extension of Zone VE. Areas of lower risk in the CHHA are designated with Zone V on the FIRM. More detailed information about the identification and designation of Zone VE is presented in Section 6.4 of this FIS Report. Areas that are not within the CHHA but are SFHAs may still be impacted by coastal flooding and damaging waves; these areas are shown as “A” zones on the FIRM. Figure 6, “Coastal Transect Schematic,” illustrates the relationship between the base flood elevation, the 1% annual chance stillwater elevation, and the ground profile as well as the location

26

of the Zone VE and Zone AE areas in an area without a PFD subject to overland wave propagation. This figure also illustrates energy dissipation and regeneration of a wave as it moves inland.

Figure 6: Coastal Transect Schematic

Methods used in coastal analyses in this Flood Risk Project are presented in Section 5.3 and mapping methods are provided in Section 6.4 of this FIS Report. Coastal floodplains are shown on the FIRM using the symbology described in Figure 3, “Map Legend for FIRM.” In many cases, the BFE on the FIRM is higher than the stillwater elevations shown in Table 17 due to the presence of wave effects. The higher elevation should be used for construction and/or floodplain management purposes.

2.5.4 Limit of Moderate Wave Action Laboratory tests and field investigations have shown that wave heights as little as 1.5 feet can cause damage to and failure of typical Zone AE building construction. Wood-frame, light gage steel, or masonry walls on shallow footings or slabs are subject to damage when exposed to waves less than 3 feet in height. Other flood hazards associated with coastal waves (floating debris, high velocity flow, erosion, and scour) can also damage Zone AE construction. Therefore, a LiMWA boundary may be shown on the FIRM as an informational layer to assist coastal communities in safe rebuilding practices. The LiMWA represents the approximate landward limit of the 1.5-foot breaking wave. The location of the LiMWA relative to Zone VE and Zone AE is shown in Figure 6. The effects of wave hazards in Zone AE between Zone VE (or the shoreline where Zone VE is not identified) and the limit of the LiMWA boundary are similar to, but less severe than, those in Zone VE where 3-foot or greater breaking waves are projected to occur during the 1% annual chance flooding event. Communities are therefore encouraged to adopt and enforce more stringent floodplain management requirements than the minimum NFIP requirements in the LiMWA. The NFIP Community Rating System provides credits for these actions.

27

Where wave runup elevations dominate over wave heights, there is no evidence to date of significant damage to residential structures by runup depths less than 3 feet. Examples of these areas include areas with steeply sloped beaches, bluffs, or flood protection structures that lie parallel to the shore. In these areas, the FIRM shows the LiMWA immediately landward of the VE/AE boundary. Similarly, in areas where the zone VE designation is based on the presence of a primary frontal dune or wave overtopping, the LiMWA is delineated immediately landward of the Zone VE/AE boundary.

SECTION 3.0 – INSURANCE APPLICATIONS

3.1 National Flood Insurance Program Insurance Zones For flood insurance applications, the FIRM designates flood insurance rate zones as described in Figure 3, “Map Legend for FIRM.” Flood insurance zone designations are assigned to flooding sources based on the results of the hydraulic or coastal analyses. Insurance agents use the zones shown on the FIRM and depths and base flood elevations in this FIS Report in conjunction with information on structures and their contents to assign premium rates for flood insurance policies. The 1% annual chance floodplain boundary corresponds to the boundary of the areas of special flood hazards (e.g. Zones A, AE, V, VE, etc.), and the 0.2% annual chance floodplain boundary corresponds to the boundary of areas of additional flood hazards. Table 3 lists the flood insurance zones in Santa Rosa County.

Table 3: Flood Zone Designations by Community

Community Flood Zone(s)

Gulf Breeze, City of AE, VE, AO, X

Jay, Town of A, X

Milton, City of AE, X

Santa Rosa County, Unincorporated Areas A, AE, VE, X

3.2 Coastal Barrier Resources System The Coastal Barrier Resources Act (CBRA) of 1982 was established by Congress to create areas along the Atlantic and Gulf coasts and the Great Lakes, where restrictions for Federal financial assistance including flood insurance are prohibited. In 1990, Congress passed the Coastal Barrier Improvement Act (CBIA), which increased the extent of areas established by the CBRA and added “Otherwise Protected Areas” (OPA) to the system. These areas are collectively referred to as the John. H Chafee Coastal Barrier Resources System (CBRS). The CBRS boundaries that have been identified in the project area are in Table 4, “Coastal Barrier Resource System Information.”

28

Table 4: Coastal Barrier Resources System Information

Primary Flooding Source CBRS/OPA Type Date CBRS Area

Established FIRM Panel Number(s)

East Bay CBRS 2/24/1997

12113C0527H 12113C0529H 12113C0531H 12113C0533G1

12113C0554H 12113C0558H

East Bay CBRS 11/16/1990

12113C0528H 12113C0529H 12113C0533G1

12113C0536H1

12113C0537H

12113C0554H 12113C0558H

Escambia Bay CBRS 11/16/1990 12113C0526H

12113C0527H

Gulf of Mexico CBRS 11/16/1990 12113C0588H

Pensacola Bay CBRS 11/16/1990

12113C0514G1

12113C0518H1

12113C0528H 12113C0529H 12113C0602H

12113C0606H

Pensacola Bay OPA 11/16/1991

12113C0519H 12113C0538H 12113C0606H 12113C0607H 12113C0608H

Santa Rosa Sound OPA 11/16/1991 12113C0607H 12113C0626H

Santa Rosa Sound CBRS 11/16/1990 12113C0588H 1 Panel Not Printed

29

SECTION 4.0 – AREA STUDIED

4.1 Basin Description Table 5 contains a description of the characteristics of the HUC-8 sub-basins within which each community falls. The table includes the main flooding sources within each basin, a brief description of the basin, and its drainage area.

Table 5: Basin Characteristics

HUC-8 Sub-Basin Name

HUC-8 Sub-Basin

Number

Primary Flooding Source Description of Affected Area

Drainage Area (square miles)

Blackwater Watershed 03140104 Blackwater

River

The Blackwater River is approximately 68 miles in length with a drainage area of approximately 865 square miles.

865

Escambia Watershed 03140305 Escambia

River

Escambia Watershed drains from Alabama south ultimately discharging into Escambia Bay.

760

Lower Conecuh Watershed 03140304 Escambia

River

The Lower Conecuh watershed is predominantly within Alabama with only approximately 12 square miles in Florida.

1,014

Pensacola Bay Watershed 03140105

Pensacola Bay, Gulf of Mexico and Santa Rosa

Sound

The Pensacola Bay watershed includes numerous contributing creeks and streams.

544

Yellow Watershed 03140103 Yellow River

The Yellow River is a 92-mile long river of which 61 miles occur in Florida’s Okaloosa, Santa Rosa and Walton Counties. The Yellow River flows in a southwesterly direction into the Blackwater Bay.

1,374

4.2 Principal Flood Problems Table 6 contains a description of the principal flood problems that have been noted for Santa Rosa County by flooding source.

30

Table 6: Principal Flood Problems

Flooding Source Description of Flood Problems

Blackwater River

Flooding in the Blackwater River Basin is caused by stream overbank flow and hurricane storm surges, and sometimes a combination of both. Riverine flooding occurs frequently and is prevalent throughout the reach of the river where the riverbanks are low and the floodplain is wide. The flat slopes and wide, heavily vegetated floodplains aggravate the flood problem by preventing the rapid drainage of floodwaters. At flood stage, the Blackwater River covers large areas, flooding forest land, farmland, fishing resorts, and other businesses built on the floodplain.

Coastal Areas The coastal areas of Santa Rosa County are subject to widespread flooding resulting from storm surges that accompany hurricanes and other severe storms from one or more of the following flooding sources: the Gulf of Mexico, East Bay, Escambia Bay, Pensacola Bay, Blackwater Bay, and Santa Rosa Sound. Present conclusions about recurrent coastal flood elevations rely heavily on historical evidence from the continuous tidal records identified in Table 5. Areas near the beach may be subject to wave action and high velocity surges that can cause erosion and property damage.

All Sources Some of the worst floods to occur in northwestern Florida were caused by high intensity rainfall during hurricanes. The time of concentration of runoff for large basin rivers in northwestern Florida may be several days; consequently, peak flows do not, as a rule, coincide with hurricane tides at the coast. The smaller streams, however, have a shorter period of concentration of runoff and flood flow occurring concurrently with storm surge is more likely. This greatly increases the likelihood of inundation of low-lying areas along the coast. Maximum rainfall ordinarily occurs in the eastern half of the storm system. As the storm passes inland its intensity decreases, but heavy rainfall continues. Total precipitation of 12 inches recorded at a single station during a hurricane is not uncommon, and in northwestern Florida, rainfall has been as high as 24 inches for the duration of the storm.

Table 7 contains information about historic flood elevations in the communities within Santa Rosa County.

Table 7: Historic Flooding Elevations (Not Applicable to this Flood Risk Project)

4.3 Non-Levee Flood Protection Measures Table 8 contains information about non-levee flood protection measures within Santa Rosa County such as dams, jetties, and or dikes. Levees are addressed in Section 4.4 of this FIS Report.

31

Table 8: Non-Levee Flood Protection Measures

Flooding Source

Structure Name

Type of Measure Location

Description of Measure

Albert Gordon Pond N/A Dam Outfall of pond N/A

Bear Creek Bear Lake Dam Dam Outfall of Beak Lake N/A

N/A N/A Dam

Approximately 500 southeast of intersection with Steeplehead Rd and Alligator Creek

N/A

Jacobs Creek N/A Dam Approximately 240 feet north of Riverview Ct. N/A

Reader Creek N/A Dam Approximately 280 feet east of Par Lane N/A

Rocky Creek Braden Ball Dam #1 Dam At Abel Avenue N/A

4.4 Levees This section is not applicable to this Flood Risk Project.

Table 9: Levees (Not Applicable to this Flood Risk Project)

SECTION 5.0 – ENGINEERING METHODS For the flooding sources in the community, standard hydrologic and hydraulic study methods were used to determine the flood hazard data required for this study. Flood events of a magnitude that are expected to be equaled or exceeded at least once on the average during any 10-, 25-, 50-, 100-, or 500-year period (recurrence interval) have been selected as having special significance for floodplain management and for flood insurance rates. These events, commonly termed the 10-, 25-, 50-, 100-, and 500-year floods, have a 10-, 4-, 2-, 1-, and 0.2% annual chance, respectively, of being equaled or exceeded during any year. Although the recurrence interval represents the long-term, average period between floods of a specific magnitude, rare floods could occur at short intervals or even within the same year. The risk of experiencing a rare flood increases when periods greater than 1 year are considered. For example, the risk of having a flood that equals or exceeds the 100-year flood (1-percent chance of annual exceedance) during the term of a 30-year mortgage is approximately 26 percent (about 3 in 10); for any 90-year period, the risk increases to approximately 60 percent (6 in 10). The analyses reported herein reflect flooding potentials based on conditions existing in the community at the time of completion of this study. Maps and flood elevations will be amended periodically to reflect future changes.

32

In addition to these flood events, the “1-percent-plus”, or “1%+”, annual chance flood elevation has been modeled and included on the flood profile for certain flooding sources in this FIS Report. While not used for regulatory or insurance purposes, this flood event has been calculated to help illustrate the variability range that exists between the regulatory 1% annual chance flood elevation and a 1% annual chance elevation that has taken into account an additional amount of uncertainty in the flood discharges (thus, the 1% “plus”). For flooding sources whose discharges were estimated using regression equations, the 1%+ flood elevations are derived by taking the 1% annual chance flood discharges and increasing the modeled discharges by a percentage equal to the average predictive error for the regression equation. For flooding sources with gage- or rainfall-runoff-based discharge estimates, the upper 84-percent confidence limit of the discharges is used to compute the 1%+ flood elevations.

5.1 Hydrologic Analyses Hydrologic analyses were carried out to establish the peak elevation-frequency relationships for floods of the selected recurrence intervals for each flooding source studied. Hydrologic analyses are typically performed at the watershed level. Depending on factors such as watershed size and shape, land use and urbanization, and natural or man-made storage, various models or methodologies may be applied. A summary of the hydrologic methods applied to develop the discharges used in the hydraulic analyses for each stream is provided in Table 13. Greater detail (including assumptions, analysis, and results) is available in the archived project documentation. A summary of the discharges is provided in Table 10. Frequency Discharge-Drainage Area Curves used to develop the hydrologic models may also be shown in Figure 7 for selected flooding sources. A summary of stillwater elevations developed for non-coastal flooding sources is provided in Table 11. (Coastal stillwater elevations are discussed in Section 5.3 and shown in Table 17.) Stream gage information is provided in Table 12.

33

Table 10: Summary of Discharges

Peak Discharge (cfs)

Flooding Source Location Drainage

Area (Square Miles)

10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance Existing

1% Annual Chance Future

0.2% Annual Chance

Beale Creek

Approximately 0.6 miles south of Vinewood lane

3.7 680 * 1,208 1,483 * 2,267

At confluence with Unnamed Tributary to Beale Creek

1.2 353 * 650 808 * 1,267

Approximately 500 feet south of Dunridge Drive

0.5 208 * 396 499 * 800

Big Coldwater Creek

At confluence with Blackwater River 257.1 10,993 * 20,033 24,902 * 39,155

At Munson Highway 237.0 10,412 * 18,961 23,562 * 37,020


221.2 9,945 * 18,098 22,484 * 35,304

Approximately 1.8 miles of confluence with East Fork and West Fork Big Coldwater Creek

210.0 9,577 * 17,399 21,601 * 33,872

Blackwater River

Approximately 1 mile northeast of U.S. Highway 90

743 35,900 * 69,900 89,900 * 152,900

At Deaton Bridge Road 300 19,777 * 40,897 53,552 * 93,589

34




Area (Square Miles)

10% Annual Chance

4% Annual Chance

2% Annual Chance



0.2% Annual Chance

At County Boundary 274 35,900 * 69,900 89,900 * 152,900

Clear Creek

At confluence with Blackwater River 24.2 2,146 * 3,743 4,570 * 6,914

At Pat Brown Road 23.4 2,097 * 3,657 4,464 * 6,752

At Munson Highway 22.5 2,041 * 3,558 4,342 * 6,565

At Blackwater Heridage State Trail 19.3 1,844 * 3,209 3,914 * 5,910

Just upstream of Langley St 16.0 1,600 * 2,764 3,362 * 5,045

Just upstream of Hunters Oak Trail 4.5 747 * 1,319 1,616 * 2,458

East Bay River

Approximately 0.5 mile upstream of the confluence with Panther Creek

83.0 5,069 * 8,563 10,385 * 15,576


Approximately 0.5 mile north of Springhill Road

93.8 6,096 * 11,349 14,215 * 22,670

At confluence with Wolt Creek 88.6 6,039 * 11,358 14,281 * 22,952

Approximately 1,000 feet northeast of Horseshoe Loop Road

78.6 5,707 * 10,813 13,634 * 22,030

35




Area (Square Miles)

10% Annual Chance

4% Annual Chance

2% Annual Chance



0.2% Annual Chance

Escambia River Just upstream of U.S. Route 90 4,084 83,665 * 163,110 209,605 * 356,680

At State Route 184 4,147 82,153 * 134,177 161,087 * 237,286

At State Route 4 3,817 76,322 * 121,929 145,039 * 208,946

Jacobs Creek

Approximately 900 feet north of confluence with Pace Mill Creek

1.1 306 * 539 660 * 1000

Approximately 100 feet north of Riverview Court

0.8 226 * 388 470 * 698

Approximately 250 feet west of Becky Lane

0.2 101 * 170 204 * 296

Juniper Creek

Approximately 0.5 mile southeast of Dupree Road

18.0 1,914 * 3,434 4,238 * 6,548

Approximately 2,000 feet south of County Mill Road

12.1 1,537 * 2,797 3,468 * 5,412

36




Area (Square Miles)

10% Annual Chance

4% Annual Chance

2% Annual Chance



0.2% Annual Chance

Manning Creek

Approximately 1,500 feet south of Highway 87

12.7 1,305 * 2,210 2,666 * 3,937

Approximately 0.5 mile northeast of Highway 87

11.7 1,241 * 2,099 2,532 * 3,736

At Van Jerigan Road 10.4 1,123 * 1,884 2,265 * 3,321

Pace Mill Creek Approximately 2,000 feet downstream of U.S. Route 90

6.2 1,838 * 3,540 4,091 * 5,881

Pond Creek

At Willard Norris Road 65.5 4,500 * 8,155 10,109 * 15,781

Approximately 400 feet west of Oser Road

54.4 3,919 * 7,049 8,712 * 13,519

Approximately 900 feet northeast of confluence with Three Hollow Creek

39.3 3,050 * 5,401 6,634 * 10,163

Approximately 450 feet east of Wendt Farm Road

18.0 1,776 * 3,102 3,788 * 5,732

Approximately 2,000 feet north of Forty Acre Pond

5.8 879 * 1,546 1,891 * 2,871

37




Area (Square Miles)

10% Annual Chance

4% Annual Chance

2% Annual Chance



0.2% Annual Chance

Reader Creek

Approximately 1,000 feet southwest of Martin Road

10.3 1,437 * 2,646 3,296 * 5,189

Approximately 100 feet northwest of Fairway Drive

6.8 1,069 * 1,946 2,414 * 3,763

Rocky Creek

Approximately 400 feet south of Pattock Place

1.4 292 * 478 568 * 812

Approximately 370 feet south of Abel Avenue

1.0 232 * 375 445 * 632

Approximately 150 feet south of Rowe Trail

0.6 146 * 228 266 * 366


At Confluence with Beale Creek 2.2 457 * 798 973 * 1,465

Approximately 400 feet south of Twin Creek Circle

0.2 53 * 75 84 * 108


Approximately 1,000 feet from confluence with East Fork Bigh Coldwater Creek

109.7 5,921 * 10,503 12,916 * 19,860

38




Area (Square Miles)

10% Annual Chance

4% Annual Chance

2% Annual Chance



0.2% Annual Chance

At confluence with Juniper Creek 62.2 4,129 * 7,333 9,020 * 13,866

Yellow River

At confluence with Blackwater Bay 1,344 33,600 * 65,550 84,240 * 143,350

Approximately 1.2 miles southeast of County Boundary

1,246 31,450 * 61,230 78,790 * 134,080

*Not calculated for this Flood Risk Project

Figure 7: Frequency Discharge-Drainage Area Curves (Not Applicable to this Flood Risk Project)

Table 11: Summary of Non-Coastal Stillwater Elevations

Elevations (feet NAVD88)

Flooding Source Location 10% Annual

Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance

B0020N At Ponding Area 139 * * * 10.9 11.2




39




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance






I0020N At Ponding Area 1 * * * 2.4 2.9











40




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance







I0342PN At Ponding Area 24 * * * 38.3 38.6










41




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance

















42




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance

















43




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance













J0015N At Ponding Area 13 * * * 21.0 21.4




44




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance

















45




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance

















46




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance



J5130PN At Ponding Area 35 * * * 30.8 30.9







K0030N At Ponding Area 93 * * * 23.7 23.9







47




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance











L0062PN At Ponding Area 6 * * * 20.2 20.3



L3000N At Ponding Area 27 * * * 20.5 20.6

M0010N At Ponding Area 142 * * * 7.7 8.1


48




Chance 4% Annual

Chance 2% Annual

Chance 1% Annual

Chance 0.2% Annual

Chance


M0040PN At Ponding Area 11 * * * 17.4 17.8














*Not calculated for this Flood Risk Project

49

Table 12: Stream Gage Information used to Determine Discharges (Not Applicable to this Flood Risk Project)

5.2 Hydraulic Analyses Analyses of the hydraulic characteristics of flooding from the sources studied were carried out to provide estimates of the elevations of floods of the selected recurrence intervals. Base flood elevations on the FIRM represent the elevations shown on the Flood Profiles and in the Floodway Data tables in the FIS Report. Rounded whole-foot elevations may be shown on the FIRM in coastal areas, areas of ponding, and other areas with static base flood elevations. These whole-foot elevations may not exactly reflect the elevations derived from the hydraulic analyses. Flood elevations shown on the FIRM are primarily intended for flood insurance rating purposes. For construction and/or floodplain management purposes, users are cautioned to use the flood elevation data presented in this FIS Report in conjunction with the data shown on the FIRM. The hydraulic analyses for this FIS were based on unobstructed flow. The flood elevations shown on the profiles are thus considered valid only if hydraulic structures remain unobstructed, operate properly, and do not fail. For streams for which hydraulic analyses were based on cross sections, locations of selected cross sections are shown on the Flood Profiles (Exhibit 1). For stream segments for which a floodway was computed (Section 6.3), selected cross sections are also listed on Table 24, “Floodway Data.” A summary of the methods used in hydraulic analyses performed for this project is provided in Table 13. Roughness coefficients are provided in Table 14 Roughness coefficients are values representing the frictional resistance water experiences when passing overland or through a channel. They are used in the calculations to determine water surface elevations. Greater detail (including assumptions, analysis, and results) is available in the archived project documentation.

50

Table 13: Summary of Hydrologic and Hydraulic Analyses

Flooding Source

Study Limits Downstream Limit

Study Limits Upstream Limit

Hydrologic Model or

Method Used

Hydraulic Model or

Method Used

Date Analyses

Completed Flood Zone

on FIRM Special Considerations

Beale Creek At confluence Escambia River

Approximately 800 feet southwest of Curtis Road

2011 Regression Equations

HEC-RAS 3.1.3 2012 AE

Big Coldwater Creek




HEC-RAS 4.1.0 2018 AE

Big Coldwater Creek


At confluence with East Fork Big Coldwater Creek and West Fork Big Coldwater Creek


HEC-RAS 3.1.3 2012 AE

Blackwater River At Interstate 10



HEC-2 V4.6.2

2012 AE w/ Floodway

Blackwater River


At County Boundary


HEC-2 V4.6.2

2012 AE

Bray Mill Creek At confluence with Escambia River


Regression Equations

HEC-RAS 3.1.3 2012 A

51


Flooding Source



Hydrologic Model or

Method Used

Hydraulic Model or

Method Used

Date Analyses



Clear Creek At confluence with Blackwater River



HEC-RAS 4.1.0 2018 AE

Clear Creek


Approximately 1,400 feet south of Forrest Hills Rd


HEC-RAS 3.1.3 2012 AE

East Bay River At confluence with East Bay

At County Boundary Bulletin 17A HEC-2 1984 AE w/

Floodway


At confluence with Big Coldwater Creek and West Fork Big Coldwater Creek

Approximately 0.5 miles east of Gordon Land Rd.


HEC-RAS 3.1.3 2012 AE

Escambia River At US 10 Just upstream

Highway 4

Log Pearson Type III

Frequency Analysis

HEC-2 2005 AE w/ Floodway

Escambia River

Just upstream Highway 4

At Florida/Alabama state line

Log Pearson Type III

Frequency Analysis

HEC-2 2005 A

Holley By The Sea Entire Watershed Entire Watershed ICPR v3.1 ICPR v3.1 2016 AE

Holley By The Sea Entire Watershed Entire Watershed ICPR v3.1 ICPR v3.1 2016 A

52


Flooding Source



Hydrologic Model or

Method Used

Hydraulic Model or

Method Used

Date Analyses



Jacobs Creek At confluence with Pace Mill Creek

At Becky Lane 2011


HEC-RAS 3.1.3 2012 AE

Juniper Creek


Approximately 0.7 miles upstream County Mill Road


HEC-RAS 3.1.3 2012 AE

Juniper Creek

Approximately 0.7 miles upstream County Mill Road

Approximately 630 feet south of Letcher Block Road


HEC-RAS 3.1.3 2012 A

Long Branch At confluence with Pond Creek

At Long Branch Pond


HEC-RAS 3.1.3 2012 A

Malloy Branch




HEC-RAS 3.1.3 2012 A

Manning Creek


At Van Jernigan Road


HEC-RAS 3.1.3 2012 AE

Pace Mill Creek

At confluence with Escambia Bay

At Chumuckla Hwy

HEC-HMS 2.2.1

HEC-RAS 3.1.1 2005 AE w/

Floodway

Pond Creek At Willard Norris Road

Just upstream Fort Acre Pond


HEC-RAS 3.1.3 2012 AE

53


Flooding Source



Hydrologic Model or

Method Used

Hydraulic Model or

Method Used

Date Analyses



Pond Creek At confluence with Blackwater River

At Willard Norris Road

HEC-HMS 2.2.1

HEC-RAS 3.1.1 2005 AE w/

Floodway

Reader Creek At confluence with Pond Creek At Fairway Drive


HEC-RAS 3.1.3 2012 AE

Rocky Creek At Confluence with Escambia River

At Rowe Trail 2011


HEC-RAS 3.1.3 2012 AE


At confluence with Beale Creek

Approximately 1,000 feet west of Cobblestone Rd


HEC-RAS 3.1.3 2012 AE


At confluence with Bray Mill Creek

Approximately 3,000 feet north of Highway 4


HEC-RAS 3.1.3 2012 A





HEC-RAS 4.1.0 2012 A





HEC-RAS 3.1.3 2012 AE



At confluence with Malloy Branch


HEC-RAS 3.1.3 2012 A

54


Flooding Source



Hydrologic Model or

Method Used

Hydraulic Model or

Method Used

Date Analyses



Yellow River At confluence with Blackwater Bay

County Boundary 2010


HEC-2 V4.6.2

2012 AE w/ Floodway

55

Table 14: Roughness Coefficients

Flooding Source Channel “n” Overbank “n”

Beale Creek 0.020 – 0.096 0.043 – 0.129

Big Coldwater Creek 0.040 – 0.083 0.040 – 0.125

Blackwater River 0.070 – 0.044 0.030 – 0.200

Clear Creek 0.065 – 0.096 0.045 – 0.129

East Bay River 0.035 – 0.045 0.150 – 0.180

East Fork Big Coldwater Creek 0.040 – 0.083 0.040 – 0.125

Escambia River 0.035 – 0.045 0.150 – 0.180

Jacobs Creek 0.065 – 0.091 0.043 – 0.124

Juniper Creek 0.040 – 0.083 0.040 – 0.125

Long Branch 0.065 – 0.091 0.043 – 0.124

Manning Creek 0.040 – 0.083 0.040 – 0.125

Pace Mill Creek 0.065 – 0.091 0.043 – 0.124

Pond Creek 0.035 – 0.050 0.043 – 0.129

Reader Creek 0.035 – 0.050 0.043 – 0.129

Rocky Creek 0.020 – 0.091 0.043 – 0.124

Unnamed Tributary to Beale Creek 0.020 – 0.091 0.043 – 0.129

West Fork Big Coldwater Creek 0.040 – 0.083 0.040 – 0.125

Yellow River 0.070 – 0.044 0.030 – 0.200

5.3 Coastal Analyses For the areas of Santa Rosa County that are impacted by coastal flooding processes, coastal flood hazard analyses were performed to provide estimates of coastal BFEs. Coastal BFEs reflect the increase in water levels during a flood event due to extreme tides and storm surge as well as overland wave effects. The following subsections provide summaries of how each coastal process was considered for this FIS Report. Greater detail (including assumptions, analysis, and results) is available in the archived project documentation. Table 15 summarizes the methods and/or models used for the coastal analyses. Refer to Section 2.5.1 for descriptions of the terms used in this section.

56

Table 15: Summary of Coastal Analyses

Flooding Source

Study Limits From

Study Limits To

Hazard Evaluated

Model or Method Used

Date Analysis

was Completed

Blackwater Bay

Entire Shoreline

Entire Shoreline

Storm Surge, Wave

Runup, Wave Height

Analysis, Erosion

ADCIRC, CHAMP,

TAW, CSHORE, Runup 2.0

2015

East Bay Entire Shoreline

Entire Shoreline

Storm Surge, Wave

Runup, Wave Height

Analysis, Erosion

ADCIRC, CHAMP,


2015

Escambia Bay Entire Shoreline

Entire Shoreline

Storm Surge, Wave

Runup, Wave Height

Analysis, Erosion

ADCIRC, CHAMP,


2015

Gulf of Mexico Entire Shoreline

Entire Shoreline

Storm Surge, Wave

Runup, Wave Height

Analysis, Erosion

ADCIRC, CHAMP,


2015

Pensacola Bay Entire Shoreline

Entire Shoreline

Storm Surge, Wave

Runup, Wave Height

Analysis, Erosion

ADCIRC, CHAMP,


2015

Santa Rosa Sound

Entire Shoreline

Entire Shoreline

Storm Surge, Wave

Runup, Wave Height

Analysis, Erosion

ADCIRC, CHAMP,


2015

5.3.1 Total Stillwater Elevations The total stillwater elevations (stillwater including storm surge plus wave setup) for the 1% annual chance flood were determined for areas subject to coastal flooding. The models and methods that were used to determine storm surge and wave setup are listed in Table 15. The stillwater elevation that was used for each transect in coastal analyses is shown in Table 17, “Coastal Transect

57

Parameters.” Figure 8 shows the total stillwater elevations for the 1% annual chance flood that was determined for this coastal analysis.

Figure 8: 1% Annual Chance Total Stillwater Elevations for Coastal Areas

Astronomical Tide Astronomical tidal statistics were generated directly from local tidal constituents by sampling the predicted tide at random times throughout the tidal epoch. Storm Surge Statistics Storm surge is modeled based on characteristics of actual storms responsible for significant coastal flooding. The characteristics of these storms are typically determined by statistical study of the regional historical record of storms or by statistical study of tidal gages.

Table 16: Tide Gage Analysis Specifics (Not Applicable to this Flood Risk Project)

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Combined Riverine and Tidal Effects This section is not applicable to this Flood Risk Project. Wave Setup Analysis Wave setup was computed during the storm surge modeling through the methods and models listed in Table 15 and included in the frequency analysis for the determination of the total stillwater elevations. The oscillating component of wave setup, dynamic wave setup, was calculated for areas subject to wave runup hazards.

5.3.2 Waves The region wide storm surge modeling system includes the Advanced Circulation Model for Oceanic, Coastal and Estuarine Waters (ADCIRC) for simulation of 2-dimensional hydrodynamics. ADCIRC was “loosely” coupled to the unstructured numerical wave model Simulating Waves Nearshore (unSWAN) to calculate the contribution of waves to total storm surge (FEMA, 2010). The resulting model system is typically referred to as SWAN+ADCIRC. A seamless modeling grid was developed to support the storm surge modeling efforts. The modeling system validation consisted of a comprehensive tidal calibration followed by a validation using carefully reconstructed wind and pressure fields for five major flood events affecting the region: Hurricane Opal, Hurricane Georges, Hurricane Ivan, Hurricane Dennis and Hurricane Katrina

Model skill was assessed by quantitative comparison of model output to wind, wave, and high water mark observations. The model was then used to re-create 295 synthetic hurricanes to create a synthetic water elevation record from which the 10-, 2-, 1-, and 0.2- percent annual chance of exceedance elevations were determined.

Wave setup results in an increased water level at the shoreline due to the breaking of waves and transfer of momentum to the water column during hurricanes and severe storms. For the Florida Panhandle and Alabama surge study, wave setup was determined directly from the coupled wave and storm surge model. The total stillwater elevation with wave setup was then used for the erosion and overland wave modeling.

5.3.3 Coastal Erosion A single storm episode can cause extensive erosion in coastal areas. Storm-induced erosion was evaluated to determine the modification to existing topography that is expected to be associated with flooding events. Erosion was evaluated using the methods listed in Table 15. The post-event eroded profile was used for the subsequent transect-based onshore wave hazard analyses.

5.3.4 Wave Hazard Analyses Overland wave hazards were evaluated to determine the combined effects of ground elevation, vegetation, and physical features on overland wave propagation and wave runup. These analyses were performed at representative transects along all shorelines for which waves were expected to be present during the floods of the selected recurrence intervals. The results of these analyses were used to determine elevations for the 1% annual chance flood.

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Transect locations were chosen with consideration given to the physical land characteristics as well as development type and density so that they would closely represent conditions in their locality. Additional consideration was given to changes in the total stillwater elevation. Transects were spaced close together in areas of complex topography and dense development or where total stillwater elevations varied. In areas having more uniform characteristics, transects were spaced at larger intervals. Transects shown in Figure 9, “Transect Location Map,” are also depicted on the FIRM. Table 17 provides the location, stillwater elevations, and starting wave conditions for each transect evaluated for overland wave hazards. In this table, “starting” indicates the parameter value at the beginning of the transect. Wave Height Analysis Wave height analyses were performed to determine wave heights and corresponding wave crest elevations for the areas inundated by coastal flooding and subject to overland wave propagation hazards. Refer to Figure 6 for a schematic of a coastal transect evaluated for overland wave propagation hazards. Wave heights and wave crest elevations were modeled using the methods and models listed in Table 15, “Summary of Coastal Analyses”. Wave Runup Analysis Wave runup analyses were performed to determine the height and extent of runup beyond the limit of stillwater inundation for the 1% annual chance flood. Wave runup is defined as the maximum vertical extent of wave uprush on a beach or structure. FEMA’s 2007 Guidelines and Specifications require the 2-percent wave runup level be computed for the coastal feature being evaluated (cliff, coastal bluff, dune, or structure) (FEMA, February 2007). The 2-percent runup level is the highest 2 percent of wave runup affecting the shoreline during the 1-percent-annual- chance flood event. Each transect defined within the study area was evaluated for the applicability of wave runup, and if necessary, the appropriate runup methodology was selected and applied to each transect. Runup elevations were then compared to WHAFIS results to determine the dominant process affecting BFEs and associated flood hazard levels. Based on wave runup rates, wave overtopping was computed following the FEMA 2007 Guidelines and Specifications. Wave runup elevations were modeled using the methods and models listed in Table 15.

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Table 17: Coastal Transect Parameters

Flood Source Coastal

Transect

Starting Wave Conditions for the 1% Annual Chance

Starting Stillwater Elevations (ft NAVD88) Range of Stillwater Elevations

(ft NAVD88)

Significant Wave Height

Hs (ft)

Peak Wave Period Tp (sec)

10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Gulf of Mexico 1 20.6 15.8 5.1 * 8.4 9.2 12.5

4.1-5.1 5.7-8.4 7.4-9.2 12.0-12.5

Gulf of Mexico 2 20.1 16.6 5.2 * 8.4 9.8 12.4

4.3-5.2 6.1-8.4 7.6-9.8 12.3-12.7

Escambia Bay 3 4.2 4.0 5.4 * 9.2 11.0 14.6

4.2-5.6 7.7-9.5 9.2-11. 12.1-15.3

Escambia Bay 4 4.5 4.2 5.6 * 9.6 11.7 15.6

5.0-5.6 8.9-9.8 11.2-11 15.6-15.7

61



Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Escambia Bay 5 4.6 4.2 5.5 * 9.6 11.5 15.5

5.2-5.5 9.2-9.6 11.2-11 15.1-15.5

Escambia Bay 6 4.4 4.3 5.3 * 9.2 11.0 14.9

4.8-5.3 8.3-9.2 10.5-11 14.4-14.9

Escambia Bay 7 4.5 4.0 5.2 * 8.8 10.5 14.3

4.6-5.2 7.7-8.9 9.2-10. 14.0-14.6

Escambia Bay 8 4.8 4.2 4.9 * 8.3 9.9 13.5

4.2-5.1 7.5-8.7 9.4-10. 13.5-14.4

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Escambia Bay 9 4.2 3.9 4.8 * 8.1 9.7 13.3

4.2-5.1 5.0-8.2 9.1-10. 13.2-14.3

Escambia Bay 10 4.1 4.1 4.7 * 7.7 9.2 12.7

3.9-4.7 3.2-7.7 8.3-9.2 12.6-13.0

Escambia Bay 11 4.2 4.5 4.6 * 7.4 8.7 11.9

4.4-4.6 5.6-7.4 7.6-8.7 10.5-11.9

Escambia Bay 12 4.0 4.3 4.3 * 7.0 7.9 10.7

3.3-4.4 5.5-7.0 6.5-7.9 9.6-10.7

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

East Bay 13 3.8 4.1 4.3 * 6.8 7.7 9.9

3.3-4.5 5.4-6.9 6.4-7.9 9.5-10.3

East Bay 14 4.1 4.1 4.6 * 7.5 8.7 11.5

3.9-4.6 5.3-7.5 8.1-8.7 11.2-11.5

Blackwater Bay 15 4.0 3.9 4.7 * 7.7 8.8 11.9

3.4-4.7 6.3-7.8 8.1-8.8 11.1-11.9

Blackwater Bay 16 3.8 3.9 4.9 * 8.0 9.3 12.4

4.9-4.9 7.0-8.0 8.3-9.3 11.7-12.4

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Blackwater Bay 17 3.7 3.7 4.9 * 8.0 9.4 12.6

4.5-4.9 7.2-8.0 8.6-9.6 11.9-12.6

Blackwater Bay 18 3.0 2.9 5.1 * 8.6 10.1 13.5

4.6-5.2 7.1-8.6 9.0-10. 12.7-13.5

Blackwater Bay 19 3.1 2.7 5.0 * 8.5 10.0 13.6

3.4-5.0 7.2-8.5 9.0-10. 12.9-13.6

Blackwater Bay 20 3.3 3.5 4.9 * 8.1 9.5 12.7

3.6-4.9 6.5-8.1 7.9-9.6 11.7-13.0

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Blackwater Bay 21 3.2 3.6 4.8 * 8.0 9.3 12.5

3.4-4.8 6.0-8.0 7.3-9.5 10.1-12.8

Blackwater Bay 22 3.1 3.7 4.8 * 7.9 9.2 12.3

3.8-4.8 6.6-7.9 8.5-9.3 11.9-12.6

Blackwater Bay 23 3.1 3.7 4.7 * 7.7 9.0 12.0

4.1-4.7 6.4-7.7 8.1-9.0 11.2-12.1

East Bay 24 3.9 4.0 4.6 * 7.5 8.8 11.8

4.2-4.6 6.4-7.5 7.3-8.8 11.4-11.8

66



Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

East Bay 25 3.7 3.9 4.5 * 7.4 8.7 11.7

4.4-4.5 7.1-7.4 7.8-8.7 11.5-11.7

East Bay 26 2.7 2.9 4.5 * 7.4 8.8 12.0

4.5-4.5 7.0-7.4 7.6-8.8 11.8-12.0

East Bay 27 2.6 2.6 4.5 * 7.4 8.8 12.0

4.3-4.5 6.6-7.4 7.3-8.8 12.0-12.3

East Bay 28 3.2 3.8 4.4 * 7.3 8.6 11.7

3.9-4.5 7.1-7.4 7.7-8.8 11.4-12.2

67



Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

East Bay 29 3.1 3.9 4.4 * 7.3 8.2 11.4

4.4-4.4 7.3-7.3 8.0-8.4 11.1-11.6

East Bay 30 3.1 3.7 4.4 * 7.2 8.0 11.1

4.4-4.4 7.2-7.2 7.4-8.0 10.8-11.1

East Bay 31 2.9 3.7 4.3 * 7.0 7.9 10.8

4.3-4.3 6.9-7.0 7.6-8.0 10.8-10.8

East Bay 32 2.9 3.5 4.3 * 7.0 7.7 10.6

4.3-4.3 6.8-7.0 7.4-7.8 10.4-10.6

68



Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

East Bay 33 2.9 3.6 4.2 * 6.9 7.7 10.3

4.2-4.2 6.9-6.9 6.6-7.7 10.3-10.3

East Bay 34 2.6 3.6 4.2 * 6.7 7.7 10.0

4.2-4.2 6.7-6.7 6.8-7.7 10.0-10.0

East Bay 35 2.5 3.6 4.1 * 6.6 7.6 9.7

4.1-4.1 5.3-6.6 6.7-7.6 9.7-9.7

Pensacola Bay 36 2.7 3.7 4.1 * 6.4 7.3 9.5

4.1-4.1 6.1-6.4 6.5-7.3 9.0-9.5

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Pensacola Bay 37 3.5 4.0 4.1 * 6.5 7.3 9.2

4.1-4.1 5.6-6.5 6.5-7.3 8.8-9.2

Pensacola Bay 38 3.7 4.2 4.1 * 6.5 7.4 9.3

4.1-4.1 6.5-6.6 7.1-7.4 9.3-9.3

Pensacola Bay 39 4.4 3.9 4.1 * 6.5 7.4 9.3

4.1-4.1 6.5-6.5 7.4-7.4 9.3-9.3

Pensacola Bay 40 4.9 4.0 4.2 * 6.5 7.4 9.3

4.1-4.2 6.5-6.5 7.4-7.4 9.3-9.4

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Pensacola Bay 41 3.7 4.4 4.3 * 6.9 7.9 10.6

4.2-4.3 6.7-6.9 7.5-7.9 10.6-10.6

Pensacola Bay 42 5.0 4.0 4.4 * 7.0 8.1 10.9

4.4-4.4 7.0-7.1 7.8-8.1 10.9-10.9

Pensacola Bay 43 5.1 3.7 4.4 * 7.1 8.3 11.7

4.3-4.4 6.9-7.1 7.8-8.3 11.7-11.7

Santa Rosa Sound 44 5.0 3.8 4.2 * 6.9 8.2 12.0

4.2-4.2 5.6-6.9 7.6-8.2 11.1-12.0

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Santa Rosa Sound 45 5.5 4.1 4.2 * 6.9 8.2 12.5

4.1-4.2 6.5-6.9 7.4-8.2 10.6-12.5

Santa Rosa Sound 46 5.6 4.2 4.1 * 6.8 8.1 12.9

4.1-4.1 6.7-6.8 6.4-8.1 12.9-12.9

Santa Rosa Sound 47 5.1 4.0 4.1 * 6.7 8.1 13.2

4.1-4.1 5.1-6.7 6.1-8.1 13.2-13.5

Santa Rosa Sound 48 5.0 4.0 4.1 * 6.5 8.0 13.3

4.1-4.1 5.1-6.5 6.5-8.0 13.3-13.8

72



Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Santa Rosa Sound 49 4.7 3.7 4.1 * 6.8 8.1 13.1

4.1-4.1 5.2-6.8 6.5-8.1 13.1-13.6

Santa Rosa Sound 50 4.3 3.4 4.1 * 6.8 8.1 13.1

4.1-4.2 6.2-6.8 6.7-8.1 12.6-13.2

Santa Rosa Sound 51 4.6 3.6 4.2 * 6.9 7.8 13.0

4.2-4.2 6.8-6.9 6.4-7.8 13.0-13.0

Santa Rosa Sound 52 4.3 3.3 4.2 * 6.9 8.3 12.9

4.2-4.2 5.4-6.9 6.7-8.3 12.9-13.0

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Santa Rosa Sound 53 4.1 3.0 4.3 * 7.0 8.4 12.9

4.2-4.3 5.7-7.0 7.8-8.4 12.9-13.4

Santa Rosa Sound 55 3.9 2.9 4.3 * 7.1 8.4 12.9

4.3-4.3 7.1-7.2 8.2-8.4 12.9-13.1

Santa Rosa Sound 56 3.6 3.1 4.3 * 7.2 8.6 13.1

4.3-4.3 7.1-7.2 8.2-8.6 12.8-13.1

Santa Rosa Sound 57 3.9 2.8 4.4 * 7.3 8.7 13.2

4.1-4.4 6.8-7.3 8.4-8.7 13.0-13.2

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Santa Rosa Sound 58 3.1 3.0 4.4 * 7.3 8.7 13.2

4.2-4.4 7.0-7.3 8.1-8.7 13.0-13.2

Santa Rosa Sound 59 3.7 3.0 4.4 * 7.4 8.7 13.3

4.4-4.4 7.3-7.4 8.1-8.7 13.0-13.4

Santa Rosa Sound 60 3.7 3.0 4.4 * 7.4 9.0 13.4

4.4-4.4 7.4-7.5 8.6-9.0 13.2-13.4

Santa Rosa Sound 61 4.1 3.0 4.4 * 7.5 8.9 13.3

4.3-4.4 7.3-7.5 8.7-9.1 13.1-13.3

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Transect



(ft NAVD88)


Hs (ft)


10% Annual Chance

4% Annual Chance

2% Annual Chance

1% Annual Chance

0.2% Annual Chance

Santa Rosa Sound 62 4.0 3.3 4.4 * 7.5 9.1 13.4

4.4-4.4 7.3-7.5 8.7-9.1 13.2-13.4

Santa Rosa Sound 63 3.8 3.1 4.5 * 7.6 9.1 13.3

4.3-4.5 7.6-7.6 9.1-9.1 13.3-13.3

Santa Rosa Sound 64 7.5 3.5 4.5 * 7.6 9.1 13.2

4.4-4.5 7.2-7.6 8.9-9.1 12.8-13.2

* Not calculated for this Flood Risk Project

NATIONAL FLOOD INSURANCE PROGRAMTRANSECT LOCATION MAP

FEMAHTTP://MSC.FEMA.GOV

THE INFORMATION DEPICTED ON THIS MAP AND SUPPORTINGDOCUMENTATION ARE ALSO AVAILABLE IN DIGITAL FORMAT AT

Map Projection:

SEE FLOOD INSURANCE STUDY FOR ADDITIONAL INFORMATION

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Santa Rosa Sound

SANTA ROSA COUNTY120274

CITY OF MILTON120276

CITY OF GULF BREEZE120275

ESCAMBIA COUNTY(AREA NOT INCLUDED)

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0 1.5 3 4.5 60.75Miles

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60,61, 62, 63, 64

and Incorporated AreasSANTA ROSA COUNTY, FLORIDASanta Rosa Transects: Florida State Plane North FIPS Zone 0903;

North American Datum 1983 HARN; GRS 1980 Spheroid

COUNTY LOCATOR

Figure 9: Transect Location Map

76

77

5.4 Alluvial Fan Analyses This section is not applicable to this Flood Risk Project

Table 18: Summary of Alluvial Fan Analyses (Not Applicable to this Flood Risk Project)

Table 19: Results of Alluvial Fan Analyses (Not Applicable to this Flood Risk Project)

SECTION 6.0 – MAPPING METHODS

6.1 Vertical and Horizontal Control All FIS Reports and FIRMs are referenced to a specific vertical datum. The vertical datum provides a starting point against which flood, ground, and structure elevations can be referenced and compared. Until recently, the standard vertical datum used for newly created or revised FIS Reports and FIRMs was the National Geodetic Vertical Datum of 1929 (NGVD29). With the completion of the North American Vertical Datum of 1988 (NAVD88), many FIS Reports and FIRMs are now prepared using NAVD88 as the referenced vertical datum. Flood elevations shown in this FIS Report and on the FIRMs are referenced to NAVD88. These flood elevations must be compared to structure and ground elevations referenced to the same vertical datum. For information regarding conversion between NGVD29 and NAVD88 or other datum conversion, visit the National Geodetic Survey website at www.ngs.noaa.gov, or contact the National Geodetic Survey (NGS) at the following address:

NGS Information Services NOAA, N/NGS12

National Geodetic Survey SSMC-3, #9202

1315 East-West Highway Silver Spring, Maryland 20910-3282

(301) 713-3242 Temporary vertical monuments are often established during the preparation of a flood hazard analysis for the purpose of establishing local vertical control. Although these monuments are not shown on the FIRM, they may be found in the archived project documentation associated with the FIS Report and the FIRMs for this community. Interested individuals may contact FEMA to access these data.


78

To obtain current elevation, description, and/or location information for benchmarks in the area, please contact the Information Services Branch of the NGS at (301) 713-3242, or visit their website at www.ngs.noaa.gov.

Table 20: Countywide Vertical Datum Conversion (Not Applicable to this Flood Risk Project)

Calculations for the vertical offsets for Escambia River basis are depicted in Table 21.

Table 21: Stream-Based Vertical Datum Conversion

Flooding Source Average Vertical Datum Conversion Factor (feet)

Escambia River -0.03

6.2 Base Map The FIRMs and FIS Report for this project have been produced in a digital format. The flood hazard information was converted to a Geographic Information System (GIS) format that meets FEMA’s FIRM database specifications and geographic information standards. This information is provided in a digital format so that it can be incorporated into a local GIS and be accessed more easily by the community. The FIRM Database includes most of the tabular information contained in the FIS Report in such a way that the data can be associated with pertinent spatial features. For example, the information contained in the Floodway Data table and Flood Profiles can be linked to the cross sections that are shown on the FIRMs. Additional information about the FIRM Database and its contents can be found in FEMA’s Guidelines and Standards for Flood Risk Analysis and Mapping, www.fema.gov/guidelines-and-standards-flood-risk-analysis-and-mapping. Base map information shown on the FIRM was derived from the sources described in Table 22.

Table 22: Base Map Sources

Data Type Data Provider Data Date Data Scale Data Description

Hydrological line and Polygon features

Santa Rosa County GIS Department

02/09/2012 N/A Hydrography

FDOT Imagery Florida Department of Transportation

09/17/2013 N/A Aerial Imagery

PLSS Santa Rosa County GIS Department

11/08/2011 N/A Public Land Survey System Boundaries

Transportation Features

Santa Rosa County GIS Department

11/08/2011 N/A Road Centerline Data


http://www.fema.gov/guidelines-and-standards-flood-risk-analysis-and-mapping

79

Table 22: Base Map Sources

Data Type Data Provider Data Date Data Scale Data Description

Coastal Barrier Resource System (CBRS) Boundaries

US Fish and Wildlife Service 04/24/2013 N/A CBRS Boundary Data

6.3 Floodplain and Floodway Delineation The FIRM shows tints, screens, and symbols to indicate floodplains and floodways as well as the locations of selected cross sections used in the hydraulic analyses and floodway computations. For riverine flooding sources, the mapped floodplain boundaries shown on the FIRM have been delineated using the flood elevations determined at each cross section; between cross sections, the boundaries were interpolated using the topographic elevation data described in Table 23. For each coastal flooding source studied as part of this FIS Report, the mapped floodplain boundaries on the FIRM have been delineated using the flood and wave elevations determined at each transect; between transects, boundaries were delineated using land use and land cover data, the topographic elevation data described in Table 23, and knowledge of coastal flood processes. In ponding areas, flood elevations were determined at each junction of the model; between junctions, boundaries were interpolated using the topographic elevation data described in Table 23. In cases where the 1% and 0.2% annual chance floodplain boundaries are close together, only the 1% annual chance floodplain boundary has been shown. Small areas within the floodplain boundaries may lie above the flood elevations but cannot be shown due to limitations of the map scale and/or lack of detailed topographic data. The floodway widths presented in this FIS Report and on the FIRM were computed for certain stream segments on the basis of equal conveyance reduction from each side of the floodplain. Floodway widths were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. Table 2 indicates the flooding sources for which floodways have been determined. The results of the floodway computations for those flooding sources have been tabulated for selected cross sections and are shown in Table 24, “Floodway Data.”

Table 23: Summary of Topographic Elevation Data used in Mapping

Source for Topographic Elevation Data

Community Flooding Source Description Scale

Contour Interval RMSEz

Accuracyz Citation

Santa Rosa County (all communities)

All within HUC basins

03140103 03140104 03140105 03140304 03140305

Light Detection and Ranging data (LiDAR)

1:1200 N/A N/A N/A NWFWMD

80

BFEs shown at cross sections on the FIRM represent the 1% annual chance water surface elevations shown on the Flood Profiles and in the Floodway Data tables in the FIS Report. Rounded whole-foot elevations may be shown on the FIRM in coastal areas, areas of ponding, and other areas with static base flood elevations.

81

Table 24: Floodway Data

LOCATION FLOODWAY 1% ANNUAL CHANCE FLOOD WATER SURFACE

ELEVATION (FEET NAVD88)

CROSS SECTION DISTANCE1 WIDTH

(FEET)

SECTION AREA

(SQ. FEET)

MEAN VELOCITY

(FEET/SEC) REGULATORY WITHOUT

FLOODWAY WITH

FLOODWAY INCREASE

A 9,342 1,380 13,046 6.9 10.1 2.82 2.8 0.0 B 10,605 2,540 20,654 4.4 10.1 5.42 5.4 0.0 C 11,960 3,491 25,814 3.5 10.1 7.62 7.8 0.2 D 14,578 2,885 32,140 2.8 10.9 10.9 11.1 0.2 E 16,459 3,242 40,638 2.2 12.0 12.0 12.2 0.2 F 17,731 2,840 37,961 2.4 13.1 13.1 13.3 0.2 G 21,056 2,640 40,268 2.2 14.4 14.4 14.5 0.1 H 23,348 3,472 55,609 1.6 15.1 15.1 15.3 0.2 I 26,807 4,846 56,390 1.6 16.1 16.1 16.4 0.3 J 31,849 5,073 76,450 1.2 16.6 16.6 17.0 0.4 K 36,996 4,605 66,788 1.3 17.9 17.9 18.5 0.6 L 37,937 4,924 62,653 1.4 18.1 18.1 18.7 0.6 M 45,014 4,615 75,934 1.2 19.0 19.0 19.6 0.6 N 49,166 4,115 55,420 1.6 19.6 19.6 20.2 0.6 O 51,919 4,230 69,460 1.2 20.5 20.5 21.1 0.6 P 55,733 3,791 46,881 1.8 21.8 21.8 22.4 0.6 Q 62,743 3,024 43,975 1.9 24.0 24.0 24.7 0.7 R 68,973 2,413 35,370 2.4 26.3 26.3 27.0 0.7 S 72,997 3,364 56,885 1.5 28.8 28.8 29.5 0.7 T 76,544 2,582 47,582 1.8 30.1 30.1 30.8 0.7 U 80,226 2,825 51,100 1.6 32.3 32.3 33.1 0.8 V 84,523 2,818 47,472 1.1 33.3 33.3 34.1 0.8 W 90,387 3,953 73,029 0.7 34.4 34.4 35.3 0.9 X 93,456 4,366 64,261 0.8 34.8 34.8 35.7 0.9 Y 97,816 2,280 40,401 1.3 36.5 36.5 37.4 0.9 Z 99,764 1,497 27,873 1.9 37.6 37.6 38.5 0.9 AA – AU3 1Feet above mouth at Blackwater Bay 2Elevation computed without consideration of Blackwater Bay storm surge effects 3Floodway data not computed, see Table 25 for elevations

TABLE 24

FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA SANTA ROSA COUNTY, FL

FLOODING SOURCE: BLACKWATER RIVER AND INCORPORATED AREAS

82




(FEET)

SECTION AREA

(SQ. FEET)

MEAN VELOCITY


FLOODWAY WITH

FLOODWAY INCREASE

A 700 200 1,912 5.4 8.9 2.12 3.1 1.0 B 2,900 200 1,862 5.6 8.9 2.52 5.1 0.6 C 5,050 260 3,121 3.3 8.9 5.82 6.3 0.5 D 5,192 260 3,130 3.3 8.9 5.82 6.3 0.5 E 12,392 1,072 7,834 1.3 8.9 7.02 7.6 0.6 F 17,192 1,971 17,802 0.6 8.9 7.82 8.6 0.8 G 21,492 806 5,254 2.0 8.9 8.32 9.1 0.8 H 25,902 801 6,718 1.5 10.4 10.4 11.4 1.0 I 28,892 941 8,686 1.2 11.9 11.9 12.9 1.0 J 33,392 820 8,455 1.2 13.2 13.2 14.2 1.0 K 36,492 1,324 11,577 0.9 14.0 14.0 15.0 1.0 L 38,842 1,346 10,788 1.0 14.5 14.5 15.5 1.0 1Feet above mouth at East Bay 2Elevation computed without consideration of East Bay storm surge effects

TABLE 24


FLOODING SOURCE: EAST BAY RIVER AND INCORPORATED AREAS

83



CROSS SECTION DISTANCE1 WIDTH3

(FEET)

SECTION AREA

(SQ. FEET)

MEAN VELOCITY


FLOODWAY WITH

FLOODWAY INCREASE

A 260 11,754 36,963 5.7 11.0 1.52 2.4 0.9 B 9,610 13,210 130,016 1.6 11.0 8.42 8.7 0.3 C 14,210 11,092 138,573 1.5 11.0 10.82 11.3 0.5 D 23,510 8,356 139,970 1.5 15.1 15.1 16.1 1.0 E 30,970 9,500 179,667 1.2 17.9 18.1 18.8 0.9 F 39,920 10,890 191,767 1.1 20.1 20.3 20.9 0.8 G 50,110 12,510 244,300 0.9 22.2 22.4 23.1 0.9 H 56,790 9,645 181,617 1.2 23.3 23.5 24.4 0.9 I 64,350 8,944 167,470 1.3 25.0 25.2 25.8 0.8 J 66,500 5,607 72,627 2.2 25.8 25.8 26.8 1.0 K 73,502 13,330 287,920 0.6 26.5 26.5 27.5 1.0 L 80,602 11,236 221,985 0.7 27.0 27.0 28.0 1.0 M 87,632 12,431 233,338 0.7 27.7 27.7 28.7 1.0 N 97,812 11,363 229,219 0.7 28.7 28.7 29.7 1.0 O 111,852 13,812 274,559 0.6 29.5 29.5 30.5 1.0 P 125,662 15,659 279,608 0.6 30.2 30.2 31.2 1.0 Q 143,062 9,964 142,340 1.1 31.7 31.7 32.7 1.0 R 150,242 9,397 154,267 1.0 33.6 33.6 34.6 1.0 S 163,342 11,869 204,753 0.8 35.8 35.8 36.8 1.0 T 173,042 10,237 150,152 1.0 37.5 37.5 38.5 1.0 U 179,742 5,863 98,286 1.6 39.6 39.6 40.6 1.0 V 193,392 7,136 118,512 1.3 44.4 44.4 45.4 1.0 W 200,492 10,827 198,320 0.8 45.8 45.8 46.8 1.0 X 211,172 15,785 267,611 0.6 46.9 46.9 47.9 1.0 Y 217,572 10,560 166,225 0.9 47.6 47.6 48.6 1.0 Z 222,972 7,733 102,943 1.5 48.8 48.8 49.8 1.0 1Feet above U.S. route 90 3Width extends beyond county boundary 2Elevation computed without consideration of Escambia Bay storm surge effects

TABLE 24


FLOODING SOURCE: ESCAMBIA RIVER AND INCORPORATED AREAS

84



CROSS SECTION DISTANCE1 WIDTH2

(FEET)

SECTION AREA

(SQ. FEET)

MEAN VELOCITY


FLOODWAY WITH

FLOODWAY INCREASE

AA 235,122 8,844 130,894 1.2 52.4 52.4 53.4 1.0 AB 243,542 8,008 133,538 1.1 54.4 54.4 55.4 1.0 AC 253,392 8,617 150,661 1.0 56.4 56.4 57.4 1.0 AD 261,042 8,022 142,296 1.1 57.6 57.6 58.6 1.0 AE 269,291 8,694 94,530 1.5 58.9 58.9 59.9 1.0 1Feet above U.S. route 90 2Width extends beyond county boundary

TABLE 24


FLOODING SOURCE: ESCAMBIA RIVER AND INCORPORATED AREAS

85




(FEET)

SECTION AREA

(SQ. FEET)

MEAN VELOCITY


FLOODWAY WITH

FLOODWAY INCREASE

A 5,801 513 2,058 4.5 11.6 10.02 11.0 1.0 B 7,987 349 1,063 5.4 14.6 14.6 15.0 0.4 C 8,153 363 2,276 3.2 17.8 17.8 18.3 0.5 D 11,417 108 638 10.1 38.2 38.2 39.0 0.8 E 14,183 290 1,354 6.0 52.4 52.4 53.3 0.9 F 15,807 175 784 5.6 61.1 61.1 61.6 0.5 G 15,876 175 1,425 3.2 64.3 64.3 65.3 1.0 H 19,148 149 831 6.3 75.4 75.4 76.4 1.0 I 21,191 170 880 5.8 86.3 86.3 87.1 0.8 J 21,265 170 1,390 5.0 89.5 89.5 90.4 0.9 K 22,708 103 361 3.4 91.0 91.0 91.8 0.8 L 23,617 95 266 5.7 95.1 95.1 95.2 0.1 M 23,695 100 874 1.8 100.3 100.3 101.2 0.9 N 24,612 50 132 9.2 101.5 101.5 101.8 0.3 O 25,751 93 262 4.7 110.0 110.0 110.3 0.3 P 25,863 86 445 3.0 113.3 113.3 114.3 1.0 Q 27,111 32 137 8.9 127.2 127.4 127.7 0.3 1Feet above mouth at Escambia Bay 2Elevation computed without consideration of Escambia Bay storm surge effects

TABLE 24


FLOODING SOURCE: PACE MILL CREEK AND INCORPORATED AREAS

86




(FEET)

SECTION AREA

(SQ. FEET)

MEAN VELOCITY


FLOODWAY WITH

FLOODWAY INCREASE

A 4,370 481 6,327 4.3 9.8 6.92 7.6 0.7 B 6,775 286 3,372 10.0 9.8 7.72 8.5 0.8 C 6,889 256 3,405 9.5 9.8 8.92 9.5 0.6 D 10,108 1,564 10,773 3.8 12.2 12.2 12.7 0.5 E 13,133 404 4,992 9.5 13.3 13.3 14.0 0.7 F 13,268 431 5,678 8.6 14.9 14.9 15.1 0.2 G 14,352 1,286 10,598 7.2 15.7 15.7 16.7 1.0 H 15,669 1,537 18,269 4.2 16.8 16.8 17.8 1.0 I 18,389 1,210 12,295 5.1 18.0 18.0 19.0 1.0 J 23,254 778 9,372 5.9 22.1 22.1 23.1 1.0 K 25,016 1,359 11,129 6.0 24.1 24.1 25.0 0.9 L 30,373 1,070 10,383 5.5 29.1 29.1 30.0 0.9 M 32,268 973 12,088 4.0 30.4 30.4 31.2 0.8 N 33,216 1,151 13,349 4.3 30.8 30.8 31.6 0.8 O 35,720 1,222 15,925 3.3 31.7 31.7 32.5 0.8 P 39,348 1,071 9,717 5.6 33.5 33.5 34.3 0.8 Q 39,427 1,071 9,959 5.5 33.7 33.7 34.6 0.9 R 40,496 1,250 8,221 8.9 35.5 35.5 36.3 0.8 S 44,985 812 9,725 6.1 42.3 42.3 43.0 0.7 T 45,461 850 11,927 4.6 42.6 42.6 43.4 0.8 U 48,988 707 8,896 3.9 44.7 44.7 45.7 1.0 V 51,399 809 9,254 5.2 46.8 46.8 47.8 1.0 W 53,324 565 5,208 6.1 48.8 48.8 49.6 0.8 X 53,463 545 5,377 5.9 49.3 49.3 50.2 0.9 Y 54,091 400 4,825 9.1 50.4 50.4 51.1 0.7 Z 54,639 669 7,530 5.9 51.4 51.4 52.3 0.9 1Feet above mouth at Blackwater River 2Elevation computed without consideration of Blackwater Bay storm surge effects

TABLE 24


FL6.OODING SOURCE: POND CREEK AND INCORPORATED AREAS

87




(FEET)

SECTION AREA

(SQ. FEET)

MEAN VELOCITY


FLOODWAY WITH

FLOODWAY INCREASE

AA 55,245 653 6,954 6.6 52.1 52.1 52.9 0.8 AB 58,228 761 7,121 7.2 56.2 56.2 57.2 1.0 AC 61,641 710 8,201 5.8 60.1 60.1 61.0 0.9 AD 65,620 1,199 11,040 5.0 63.7 63.7 64.6 0.9 AE 66,421 1,511 9,341 6.5 64.6 64.6 65.3 0.7 AF 69,258 1,046 7,590 4.0 67.0 67.0 67.7 0.7 AG 69,388 1,046 8,514 3.7 67.7 67.7 68.6 0.9 AH – AT2 1Feet above mouth at Blackwater River 2Floodway data not computed, see Table 25 for elevations

TABLE 24


FLOODING SOURCE: POND CREEK AND INCORPORATED AREAS

88




(FEET)

SECTION AREA

(SQ. FEET)

MEAN VELOCITY


FLOODWAY WITH

FLOODWAY INCREASE

A 10,736 7,168 27,383 3.1 9.2 5.42 5.8 0.4 B 27,462 8,709 104,290 0.8 13.8 13.8 14.3 0.5 C 33,390 4,792 67,440 1.3 15.5 15.5 16.0 0.5 D 33,496 7,792 66,198 1.3 15.6 15.6 16.1 0.5 E 43,293 7,329 90,711 0.9 16.9 16.9 17.4 0.5 F 51,322 8,731 113,669 0.7 18.4 18.4 18.9 0.5 G 58,514 5,841 79,198 1.0 20.2 20.2 20.7 0.5 H 66,628 5,231 79,414 1.0 22.6 22.6 23.1 0.5 I 81,427 6,118 88,489 0.9 24.7 24.7 25.3 0.6 J 87,896 5,863 77,674 1.0 27.0 27.0 27.6 0.6 K 96,564 4,124 67,502 1.2 28.9 28.9 29.4 0.5 L 103,524 5,476 82,647 0.9 30.3 30.3 30.8 0.5 M 109,668 6,786 100,699 0.8 31.5 31.5 32.0 0.5 N3 113,349 7,073 84,793 0.9 31.9 31.9 32.4 0.5

1Feet above mouth at Blackwater Bay 2Elevation computed without consideration of Blackwater Bay storm surge effects

3Floodway is shown outside of the county boundary

TABLE 24


FLOODING SOURCE: YELLOW RIVER AND INCORPORATED AREAS

89

Table 25: Flood Hazard and Non-Encroachment Data for Selected Streams

Flooding Source Cross

Section Stream Station1

1% Annual Chance Flood

Discharge (cfs)

1% Annual Chance Water

Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right

Beale Creek 94 11,605 * 11.8 N/A N/A

Beale Creek 93 12,127 * 13.8 N/A N/A

Beale Creek 92 12,334 * 14.3 N/A N/A

Beale Creek 91 12,381 * 14.3 N/A N/A

Beale Creek 90 12,471 * 14.6 N/A N/A

Beale Creek 89 12,561 * 16.5 N/A N/A

Beale Creek 88 12,722 * 17.9 N/A N/A

Beale Creek 87 12,882 * 18.5 N/A N/A

Beale Creek 86 13,237 * 19.1 N/A N/A

Beale Creek 85 13,289 * 19.1 N/A N/A

Beale Creek 84 13,450 * 19.7 N/A N/A

Beale Creek A 14,142 * 24.4 N/A N/A

Beale Creek B 15,153 * 28.2 N/A N/A

Beale Creek 81 15,723 * 31.5 N/A N/A

Beale Creek 80 16,392 * 37.2 N/A N/A

Beale Creek 79 16,562 * 38.6 N/A N/A

Beale Creek C 16,647 * 39.8 N/A N/A

Beale Creek 77 16,707 * 39.8 N/A N/A

Beale Creek 76 17,300 * 40.6 N/A N/A

Beale Creek D 17,596 * 43.7 N/A N/A

Beale Creek 74 17,950 * 46.0 N/A N/A

Beale Creek 73 18,657 * 52.4 N/A N/A

Beale Creek E 19,875 * 61.9 N/A N/A Big Coldwater Creek 930 0 * 23.8 N/A N/A

Big Coldwater Creek 929 2,392 * 23.8 N/A N/A


Big Coldwater Creek A 6,511 * 23.8 N/A N/A

90





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right Big Coldwater Creek 926 8,184 * 23.8 N/A N/A


Big Coldwater Creek B 12,405 * 24.2 N/A N/A





Big Coldwater Creek C 17,651 * 27.5 N/A N/A



Big Coldwater Creek D 22,671 * 29.0 N/A N/A


Big Coldwater Creek E 28,029 * 32.5 N/A N/A



Big Coldwater Creek F 34,265 * 34.9 N/A N/A



Big Coldwater Creek G 39,657 * 37.6 N/A N/A




91





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right Big Coldwater Creek 103 43,738 * 39.2 N/A N/A

Big Coldwater Creek H 44,657 * 39.8 N/A N/A






Big Coldwater Creek I 50,656 * 43.6 N/A N/A






Big Coldwater Creek J 56,651 * 48.5 N/A N/A





Big Coldwater Creek K 61,077 * 50.8 N/A N/A

Blackwater River 613 100,371 * 37.9 N/A N/A




92





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right


Blackwater River AA 103,473 * 39.3 N/A N/A


Blackwater River AB 105,593 * 40.6 N/A N/A



Blackwater River AC 111,459 * 43.5 N/A N/A



Blackwater River AD 116,529 * 46.3 N/A N/A




Blackwater River AE 119,914 * 48.1 N/A N/A




Blackwater River AF 123,825 * 49.5 N/A N/A



Blackwater River AG 128,077 * 50.6 N/A N/A




Blackwater River AH 133,378 * 52.0 N/A N/A



Blackwater River AI 136,277 * 53.4 N/A N/A


93





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right



Blackwater River AJ 140,562 * 55.5 N/A N/A


Blackwater River AK 145,563 * 57.1 N/A N/A



Blackwater River AL 147,370 * 57.6 N/A N/A

Blackwater River AM 147,427 * 57.6 N/A N/A




Blackwater River AN 150,858 * 59.1 N/A N/A



Blackwater River AO 155,016 * 60.9 N/A N/A



Blackwater River AP 158,349 * 62.0 N/A N/A



Blackwater River AQ 162,478 * 63.3 N/A N/A




Blackwater River AR 167,062 * 65.5 N/A N/A




94





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right

Blackwater River AS 170,370 * 67.0 N/A N/A



Blackwater River AT 173,528 * 68.4 N/A N/A



Blackwater River AU 176,677 * 70.2 N/A N/A



Bray Mill Creek 710 1,969 * 49.8 N/A N/A




















95





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right


Clear Creek 908 0 * 18.2 N/A N/A

Clear Creek 907 1,265 * 18.2 N/A N/A

Clear Creek 906 2,538 * 18.2 N/A N/A

Clear Creek 905 2,861 * 18.2 N/A N/A

Clear Creek 904 3,196 * 18.2 N/A N/A

Clear Creek 903 3,227 * 18.2 N/A N/A

Clear Creek 902 3,611 * 18.2 N/A N/A

Clear Creek 901 4,376 * 18.2 N/A N/A

Clear Creek 900 4,439 * 18.2 N/A N/A

Clear Creek 899 4,836 * 18.2 N/A N/A

Clear Creek 898 5,164 * 18.2 N/A N/A

Clear Creek 897 5,859 * 18.2 N/A N/A

Clear Creek 896 6,258 * 18.2 N/A N/A

Clear Creek 895 6,544 * 18.2 N/A N/A

Clear Creek 894 6,711 * 18.2 N/A N/A

Clear Creek A 7,201 * 18.2 N/A N/A

Clear Creek 892 9,362 * 18.2 N/A N/A

Clear Creek 891 11,364 * 18.2 N/A N/A

Clear Creek B 13,197 * 19.1 N/A N/A

Clear Creek 889 15,093 * 21.6 N/A N/A

Clear Creek C 16,396 * 23.4 N/A N/A

Clear Creek 123 17,984 * 26.0 N/A N/A

Clear Creek 124 19,746 * 28.7 N/A N/A

Clear Creek D 21,122 * 31.9 N/A N/A

Clear Creek 126 22,222 * 35.2 N/A N/A

Clear Creek 127 24,094 * 36.3 N/A N/A

Clear Creek 128 25,667 * 37.0 N/A N/A

Clear Creek E 27,093 * 40.3 N/A N/A

96





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right

Clear Creek 130 28,766 * 43.1 N/A N/A

Clear Creek 131 30,091 * 45.4 N/A N/A

Clear Creek 132 30,344 * 46.0 N/A N/A

Clear Creek 133 30,643 * 47.3 N/A N/A

Clear Creek 134 30,741 * 49.1 N/A N/A

Clear Creek F 31,029 * 49.6 N/A N/A

Clear Creek 136 32,750 * 51.2 N/A N/A

Clear Creek 137 34,062 * 55.6 N/A N/A

Clear Creek 138 34,283 * 56.8 N/A N/A

Clear Creek G 34,369 * 58.1 N/A N/A

Clear Creek 140 34,549 * 58.2 N/A N/A

Clear Creek 141 35,119 * 58.2 N/A N/A

Clear Creek 142 35,353 * 58.2 N/A N/A

Clear Creek 143 35,565 * 58.3 N/A N/A

Clear Creek 144 37,122 * 58.3 N/A N/A

Clear Creek H 38,405 * 58.6 N/A N/A

Clear Creek 146 39,921 * 60.1 N/A N/A

Clear Creek 147 41,298 * 61.7 N/A N/A

Clear Creek I 41,389 * 68.6 N/A N/A

Clear Creek 149 42,792 * 68.6 N/A N/A

Clear Creek 150 44,132 * 69.0 N/A N/A

Clear Creek 151 45,137 * 76.4 N/A N/A

Clear Creek 152 45,467 * 77.0 N/A N/A

Clear Creek 153 45,556 * 77.0 N/A N/A

Clear Creek 154 46,643 * 77.0 N/A N/A

Clear Creek J 47,298 * 77.1 N/A N/A

Clear Creek 156 48,923 * 77.8 N/A N/A

Clear Creek 157 50,275 * 91.3 N/A N/A

Clear Creek 158 51,078 * 110.2 N/A N/A

97





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right

Clear Creek K 51,600 * 127.2 N/A N/A East Fork Big Coldwater Creek A 3,229 * 51.5 N/A N/A

East Fork Big Coldwater Creek 165 3,975 * 51.8 N/A N/A




East Fork Big Coldwater Creek B 5,952 * 52.7 N/A N/A






East Fork Big Coldwater Creek C 11,546 * 56.0 N/A N/A





East Fork Big Coldwater Creek D 16,448 * 59.7 N/A N/A





98





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right East Fork Big Coldwater Creek 187 20,988 * 62.7 N/A N/A

East Fork Big Coldwater Creek E 21,998 * 63.3 N/A N/A






East Fork Big Coldwater Creek F 27,605 * 66.6 N/A N/A





East Fork Big Coldwater Creek G 32,527 * 71.1 N/A N/A





East Fork Big Coldwater Creek H 36,493 * 74.0 N/A N/A



East Fork Big Coldwater Creek I 38,778 * 76.1 N/A N/A

Escambia River C 14,210 * 11.0 N/A N/A

99





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right

Escambia River D 23,510 * 15.1 N/A N/A

Escambia River E 30,970 * 17.9 N/A N/A

Escambia River F 39,920 * 20.1 N/A N/A

Jacobs Creek 275 1,279 * 23.0 N/A N/A

Jacobs Creek A 1,688 * 28.4 N/A N/A





Jacobs Creek B 3,240 * 40.3 N/A N/A



Jacobs Creek C 4,139 * 44.2 N/A N/A


Jacobs Creek D 5,111 * 47.0 N/A N/A

Juniper Creek A 1,357 * 84.3 N/A N/A

Juniper Creek 233 2,173 * 84.5 N/A N/A






Juniper Creek B 6,638 * 92.1 N/A N/A






Juniper Creek C 11,822 * 100.5 N/A N/A

100





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right







Juniper Creek D 17,348 * 109.8 N/A N/A






Juniper Creek E 21,885 * 121.1 N/A N/A






Juniper Creek F 26,475 * 130.2 N/A N/A











101





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right









Long Branch 881 2,255 * 37.9 N/A N/A

Long Branch 880 2,705 * 39.8 N/A N/A

Long Branch 879 2,950 * 41.9 N/A N/A

Long Branch 878 3,073 * 42.8 N/A N/A

Long Branch 877 3,121 * 44.1 N/A N/A

Long Branch 876 3,330 * 44.2 N/A N/A

Long Branch 875 3,755 * 44.5 N/A N/A

Long Branch 874 4,070 * 44.9 N/A N/A

Long Branch 873 4,157 * 47.8 N/A N/A

Long Branch 872 5,133 * 47.8 N/A N/A

Long Branch 871 6,086 * 52.7 N/A N/A

Long Branch 870 7,281 * 56.1 N/A N/A

Long Branch 869 7,575 * 58.5 N/A N/A

Long Branch 868 7,705 * 61.1 N/A N/A

Long Branch 867 7,974 * 61.2 N/A N/A

Long Branch 866 11,331 * 71.7 N/A N/A

Long Branch 865 12,877 * 77.4 N/A N/A

Long Branch 864 14,178 * 85.1 N/A N/A

Malloy Branch 780 49 * 115.3 N/A N/A

Malloy Branch 779 576 * 115.5 N/A N/A

Malloy Branch 778 1,278 * 115.9 N/A N/A

102





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right






























103





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right









Manning Creek A 2,628 * 56.4 N/A N/A

Manning Creek 239 2,942 * 56.4 N/A N/A





Manning Creek B 6,850 * 61.8 N/A N/A





Manning Creek C 11,308 * 69.3 N/A N/A




Manning Creek D 16,408 * 76.5 N/A N/A





Manning Creek E 22,144 * 86.7 N/A N/A

104





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right








Manning Creek F 28,330 * 98.5 N/A N/A

Pace Mill Creek M3 8,969 * 18.3 N/A N/A

Pond Creek AH 69,525 * 68.8 N/A N/A

Pond Creek 526 70,127 * 69.0 N/A N/A

Pond Creek 525 71,305 * 69.3 N/A N/A

Pond Creek 524 72,556 * 69.7 N/A N/A

Pond Creek 523 73,499 * 70.1 N/A N/A

Pond Creek AI 74,748 * 71.1 N/A N/A

Pond Creek 521 76,785 * 73.7 N/A N/A

Pond Creek 520 79,397 * 76.8 N/A N/A

Pond Creek AJ 82,814 * 80.9 N/A N/A

Pond Creek 519 85,791 * 84.3 N/A N/A

Pond Creek 518 87,127 * 86.7 N/A N/A

Pond Creek AK 89,152 * 89.6 N/A N/A

Pond Creek 516 91,964 * 92.6 N/A N/A

Pond Creek 515 94,649 * 96.0 N/A N/A

Pond Creek 514 96,917 * 98.4 N/A N/A

Pond Creek 513 97,333 * 99.2 N/A N/A

Pond Creek AL 97,394 * 99.5 N/A N/A

Pond Creek 511 97,520 * 99.7 N/A N/A

Pond Creek 510 97,645 * 100.3 N/A N/A

Pond Creek 509 99,549 * 103.6 N/A N/A

105





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right

Pond Creek 508 100,817 * 105.3 N/A N/A

Pond Creek 507 102,342 * 106.6 N/A N/A

Pond Creek AM 104,309 * 109.2 N/A N/A

Pond Creek 505 106,798 * 111.3 N/A N/A

Pond Creek 504 107,175 * 111.8 N/A N/A

Pond Creek 503 108,600 * 114.6 N/A N/A

Pond Creek 502 109,928 * 116.0 N/A N/A

Pond Creek 501 110,574 * 116.8 N/A N/A

Pond Creek 500 111,267 * 118.5 N/A N/A

Pond Creek AN 111,300 * 118.6 N/A N/A

Pond Creek 498 111,528 * 119.0 N/A N/A

Pond Creek 497 112,475 * 119.7 N/A N/A

Pond Creek 496 113,884 * 120.8 N/A N/A

Pond Creek 495 117,117 * 127.7 N/A N/A

Pond Creek AO 119,412 * 130.1 N/A N/A

Pond Creek 493 121,643 * 131.8 N/A N/A

Pond Creek 492 123,460 * 134.9 N/A N/A

Pond Creek 491 125,832 * 140.2 N/A N/A

Pond Creek 490 127,446 * 146.0 N/A N/A

Pond Creek 489 128,443 * 148.5 N/A N/A

Pond Creek 488 128,813 * 149.7 N/A N/A

Pond Creek AP 128,879 * 151.1 N/A N/A

Pond Creek 486 129,061 * 151.3 N/A N/A

Pond Creek 485 131,273 * 155.6 N/A N/A

Pond Creek 484 133,661 * 162.3 N/A N/A

Pond Creek 483 135,410 * 169.9 N/A N/A

Pond Creek 482 137,764 * 181.3 N/A N/A

Pond Creek AQ 138,256 * 183.7 N/A N/A

Pond Creek 481 138,327 * 183.7 N/A N/A

106





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right

Pond Creek 480 138,579 * 184.7 N/A N/A

Pond Creek 479 139,546 * 187.8 N/A N/A

Pond Creek 478 141,648 * 191.8 N/A N/A

Pond Creek 477 143,734 * 192.3 N/A N/A

Pond Creek AR 145,534 * 192.8 N/A N/A

Pond Creek 475 147,006 * 194.1 N/A N/A

Pond Creek 474 147,853 * 194.6 N/A N/A

Pond Creek 473 148,699 * 196.7 N/A N/A

Pond Creek 472 149,308 * 197.3 N/A N/A

Pond Creek 471 149,916 * 197.6 N/A N/A

Pond Creek 470 150,525 * 197.7 N/A N/A

Pond Creek 469 151,012 * 197.8 N/A N/A

Pond Creek AS 151,054 * 197.8 N/A N/A

Pond Creek 467 151,306 * 198.0 N/A N/A

Pond Creek 466 152,634 * 198.2 N/A N/A

Pond Creek 465 154,979 * 198.5 N/A N/A

Pond Creek AT 156,209 * 203.0 N/A N/A

Reader Creek 400 535 * 70.0 N/A N/A

Reader Creek 399 1,358 * 70.1 N/A N/A

Reader Creek A 1,402 * 70.2 N/A N/A








Reader Creek B 6,576 * 81.7 N/A N/A


107





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right



Reader Creek C 12,391 * 103.1 N/A N/A



Reader Creek D 16,215 * 122.8 N/A N/A






Reader Creek E 19,143 * 152.7 N/A N/A

Rocky Creek A 10,460 * 14.0 N/A N/A

Rocky Creek 410 10,951 * 16.1 N/A N/A

Rocky Creek 409 11,566 * 18.2 N/A N/A

Rocky Creek B 12,663 * 20.5 N/A N/A

Rocky Creek 408 13,678 * 23.9 N/A N/A

Rocky Creek 407 14,161 * 27.1 N/A N/A

Rocky Creek 406 14,538 * 28.7 N/A N/A

Rocky Creek C 14,770 * 48.4 N/A N/A

Rocky Creek 404 15,201 * 48.4 N/A N/A

Rocky Creek 403 15,794 * 48.4 N/A N/A

Rocky Creek 402 17,157 * 48.4 N/A N/A

Rocky Creek D 17,378 * 62.9 N/A N/A Unnamed Tributary to Beale Creek

99 568 * 20.3 N/A N/A


A 1,083 * 25.2 N/A N/A

108





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right Unnamed Tributary to Beale Creek

97 2,340 * 36.8 N/A N/A


B 3,464 * 40.1 N/A N/A


C 5,063 * 46.2 N/A N/A


883 78 * 68.7 N/A N/A


740 266 * 70.7 N/A N/A


739 455 * 73.1 N/A N/A


738 644 * 75.7 N/A N/A


737 1,750 * 85.2 N/A N/A


736 2,784 * 99.7 N/A N/A


735 3,808 * 121.1 N/A N/A


734 4,823 * 138.4 N/A N/A


733 5,660 * 159.1 N/A N/A


732 7,203 * 177.0 N/A N/A


731 8,693 * 205.9 N/A N/A


730 9,993 * 246.2 N/A N/A

109





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right Unnamed Tributary to Escambia River

708 2,360 * 52.7 N/A N/A


882 2,997 * 53.9 N/A N/A


707 3,404 * 56.0 N/A N/A


706 4,356 * 63.0 N/A N/A


705 4,839 * 67.9 N/A N/A


704 5,682 * 73.8 N/A N/A


703 6,779 * 80.6 N/A N/A


702 7,460 * 84.4 N/A N/A


701 8,371 * 89.7 N/A N/A


700 9,411 * 100.3 N/A N/A


699 10,418 * 105.9 N/A N/A


698 11,437 * 118.1 N/A N/A


697 12,324 * 135.0 N/A N/A


696 13,223 * 146.9 N/A N/A


695 13,741 * 155.7 N/A N/A

110





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)

Left Right West Fork Big Coldwater Creek 412 2,724 * 51.2 N/A N/A

West Fork Big Coldwater Creek F 5,001 * 51.4 N/A N/A

West Fork Big Coldwater Creek 436 5,952 * 51.7 N/A N/A






West Fork Big Coldwater Creek G 11,148 * 55.0 N/A N/A







West Fork Big Coldwater Creek H 16,903 * 57.8 N/A N/A





West Fork Big Coldwater Creek I 21,857 * 60.7 N/A N/A


111





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)




West Fork Big Coldwater Creek J 26,724 * 63.4 N/A N/A






West Fork Big Coldwater Creek K 32,691 * 66.4 N/A N/A






West Fork Big Coldwater Creek L 38,695 * 71.8 N/A N/A





West Fork Big Coldwater Creek M 43,558 * 77.5 N/A N/A


112





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)






West Fork Big Coldwater Creek N 48,085 * 84.0 N/A N/A



West Fork Big Coldwater Creek O 50,487 * 84.4 N/A N/A














113





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)























114





Discharge (cfs)


Surface Elevation

(feet NAVD88)

Non-Encroachment

Width (feet)










1 Feet above mouth *Not calculated for this Flood Risk Project

6.4 Coastal Flood Hazard Mapping Flood insurance zones and BFEs including the wave effects were identified on each transect based on the results from the onshore wave hazard analyses. Between transects, elevations were interpolated using topographic maps, land-use and land-cover data, and knowledge of coastal flood processes to determine the aerial extent of flooding. Sources for topographic data are shown in Table 23. Zone VE is subdivided into elevation zones and BFEs are provided on the FIRM. The limit of Zone VE shown on the FIRM is defined as the farthest inland extent of any of these criteria (determined for the 1% annual chance flood condition):

• The primary frontal dune zone is defined in 44 CFR Section 59.1 of the NFIP regulations. The primary frontal dune represents a continuous or nearly continuous mound or ridge of sand with relatively steep seaward and landward slopes that occur immediately landward and adjacent to the beach. The primary frontal dune zone is subject to erosion and overtopping from high tides and waves during major coastal storms. The inland limit of the primary frontal dune zone occurs at the point where there is a distinct change from a

115

relatively steep slope to a relatively mild slope.

• The wave runup zone occurs where the (eroded) ground profile is 3.0 feet or more below the 2-percent wave runup elevation.

• The wave overtopping splash zone is the area landward of the crest of an overtopped

barrier, in cases where the potential 2-percent wave runup exceeds the barrier crest elevation by 3.0 feet or more.

• The breaking wave height zone occurs where 3-foot or greater wave heights could occur

(this is the area where the wave crest profile is 2.1 feet or more above the total stillwater elevation).

• The high-velocity flow zone is landward of the overtopping splash zone (or area on a

sloping beach or other shore type), where the product of depth of flow times the flow velocity squared (hv2) is greater than or equal to 200 ft3/sec2. This zone may only be used on the Pacific Coast.

The SFHA boundary indicates the limit of SFHAs shown on the FIRM as either “V” zones or “A” zones. Table 26 indicates the coastal analyses used for floodplain mapping and the criteria used to determine the inland limit of the open-coast Zone VE and the SFHA boundary at each transect.

Table 26: Summary of Coastal Transect Mapping Considerations

Coastal Transect

Primary Frontal

Dune (PFD) Identified

Wave Runup Analysis

Wave Height Analysis

Zone VE Limit

SFHA Boundary

Zone Designation

and BFE (ft NAVD 88)

Zone Designation


1 YES N/A VE 11-14 AE 8-11 PFD WHAFIS

2 YES N/A VE 12-15 AE 8-12 PFD PFD &

WHAFIS

3 NO N/A VE 13-16 AE 10-13 WHAFIS WHAFIS






116


Coastal Transect

Primary Frontal


Wave Runup Analysis


Zone VE Limit

SFHA Boundary

Zone Designation


Zone Designation





















117


Coastal Transect

Primary Frontal


Wave Runup Analysis


Zone VE Limit

SFHA Boundary

Zone Designation


Zone Designation







33 NO VE 10 VE 10-11 AE 8-10 WHAFIS RUNUP

34 NO VE 11 VE 10-11 AE 7-10 RUNUP RUNUP

35 NO VE 11 VE 10 AE 8-10 RUNUP RUNUP

36 NO AE 10 VE 9-10 AE 6-9 RUNUP RUNUP


38 NO AE 9 VE 9-11 AE 7-9 WHAFIS RUNUP


40 NO VE 11 VE 10-11 AE 7-10 RUNUP

RUNUP & OVERTOPPI

NG








118


Coastal Transect

Primary Frontal


Wave Runup Analysis


Zone VE Limit

SFHA Boundary

Zone Designation


Zone Designation


















A LiMWA boundary has also been added in coastal areas subject to wave action for use by local communities in safe rebuilding practices. The LiMWA represents the approximate landward limit of the 1.5-foot breaking wave. To simplify representation, the LiMWA was continued immediately landward of the VE/AE boundary in areas where wave runup elevations dominate. Similarly, in areas where the Zone VE designation is based on the presence of a primary frontal dune or wave overtopping, the LiMWA was delineated immediately landward of the Zone VE/AE boundary.

119

6.5 FIRM Revisions This FIS Report and the FIRM are based on the most up-to-date information available to FEMA at the time of its publication; however, flood hazard conditions change over time. Communities or private parties may request flood map revisions at any time. Certain types of requests require submission of supporting data. FEMA may also initiate a revision. Revisions may take several forms, including Letters of Map Amendment (LOMAs), Letters of Map Revision Based on Fill (LOMR-Fs), Letters of Map Revision (LOMRs) (referred to collectively as Letters of Map Change (LOMCs)), Physical Map Revisions (PMRs), and FEMA-contracted restudies. These types of revisions are further described below. Some of these types of revisions do not result in the republishing of the FIS Report. To assure that any user is aware of all revisions, it is advisable to contact the community repository of flood-hazard data (shown in Table 31, “Map Repositories”).

6.5.1 Letters of Map Amendment A LOMA is an official revision by letter to an effective NFIP map. A LOMA results from an administrative process that involves the review of scientific or technical data submitted by the owner or lessee of property who believes the property has incorrectly been included in a designated SFHA. A LOMA amends the currently effective FEMA map and establishes that a specific property is not located in a SFHA. A LOMA cannot be issued for properties located on the PFD (primary frontal dune). To obtain an application for a LOMA, visit www.fema.gov/floodplain-management/letter-map-amendment-loma and download the form “MT-1 Application Forms and Instructions for Conditional and Final Letters of Map Amendment and Letters of Map Revision Based on Fill”. Visit the “Flood Map-Related Fees” section to determine the cost, if any, of applying for a LOMA. FEMA offers a tutorial on how to apply for a LOMA. The LOMA Tutorial Series can be accessed at www.fema.gov/online-tutorials.

For more information about how to apply for a LOMA, call the FEMA Map Information eXchange; toll free, at 1-877-FEMA MAP (1-877-336-2627).

6.5.2 Letters of Map Revision Based on Fill A LOMR-F is an official revision by letter to an effective NFIP map. A LOMR-F states FEMA’s determination concerning whether a structure or parcel has been elevated on fill above the base flood elevation and is, therefore, excluded from the SFHA. Information about obtaining an application for a LOMR-F can be obtained in the same manner as that for a LOMA, by visiting www.fema.gov/floodplain-management/letter-map-amendment-loma for the “MT-1 Application Forms and Instructions for Conditional and Final Letters of Map Amendment and Letters of Map Revision Based on Fill” or by calling the FEMA Map Information eXchange, toll free, at 1-877-FEMA MAP (1-877-336-2627). Fees for applying for a LOMR-F, if any, are listed in the “Flood Map-Related Fees” section. A tutorial for LOMR-F is available at www.fema.gov/online-tutorials.

http://www.fema.gov/floodplain-management/letter-map-amendment-loma

http://www.fema.gov/floodplain-management/letter-map-amendment-loma


https://www.fema.gov/floodplain-management/letter-map-amendment-loma


120

6.5.3 Letters of Map Revision A LOMR is an official revision to the currently effective FEMA map. It is used to change flood zones, floodplain and floodway delineations, flood elevations and planimetric features. All requests for LOMRs should be made to FEMA through the chief executive officer of the community, since it is the community that must adopt any changes and revisions to the map. If the request for a LOMR is not submitted through the chief executive officer of the community, evidence must be submitted that the community has been notified of the request. To obtain an application for a LOMR, visit www.fema.gov/national-flood-insurance-program-flood-hazard-mapping/mt-2-application-forms-and-instructions and download the form “MT-2 Application Forms and Instructions for Conditional Letters of Map Revision and Letters of Map Revision”. Visit the “Flood Map-Related Fees” section to determine the cost of applying for a LOMR. For more information about how to apply for a LOMR, call the FEMA Map Information eXchange; toll free, at 1-877-FEMA MAP (1-877-336-2627) to speak to a Map Specialist. Previously issued mappable LOMCs (including LOMRs) that have been incorporated into the Santa Rosa County FIRM are listed in Table 27.

Table 27: Incorporated Letters of Map Change (Not Applicable to this Flood Risk Project)

6.5.4 Physical Map Revisions A PMR is Physical Map Revisions (PMRs) are an official republication of a community’s NFIP map to effect changes to base flood elevations, floodplain boundary delineations, regulatory floodways and planimetric features. These changes typically occur as a result of structural works or improvements, annexations resulting in additional flood hazard areas or correction to base flood elevations or SFHAs. The community’s chief executive officer must submit scientific and technical data to FEMA to support the request for a PMR. The data will be analyzed and the map will be revised if warranted. The community is provided with copies of the revised information and is afforded a review period. When the base flood elevations are changed, a 90-day appeal period is provided. A 6-month adoption period for formal approval of the revised map(s) is also provided. For more information about the PMR process, please visit www.fema.gov and visit the “Flood Map Revision Processes” section.

6.5.5 Contracted Restudies The NFIP provides for a periodic review and restudy of flood hazards within a given community. FEMA accomplishes this through a national watershed-based mapping needs assessment strategy, known as the Coordinated Needs Management Strategy (CNMS). The CNMS is used by FEMA to assign priorities and allocate funding for new flood hazard analyses used to update the FIS Report and FIRM. The goal of CNMS is to define the validity of the engineering study data within a mapped inventory. The CNMS is used to track the assessment process, document engineering gaps and their resolution, and aid in prioritization for using flood risk as a key factor for areas identified for flood map updates. Visit www.fema.gov to learn more about the CNMS or contact the FEMA Regional Office listed in Section 8 of this FIS Report.

https://www.fema.gov/national-flood-insurance-program-flood-hazard-mapping/mt-2-application-forms-and-instructions

https://www.fema.gov/national-flood-insurance-program-flood-hazard-mapping/mt-2-application-forms-and-instructions

http://www.fema.gov/


121

6.5.6 Community Map History The current FIRM presents flooding information for the entire geographic area of Santa Rosa County. Previously, separate FIRMs, Flood Hazard Boundary Maps (FHBMs) and/or Flood Boundary and Floodway Maps (FBFMs) may have been prepared for the incorporated communities and the unincorporated areas in the county that had identified SFHAs. Current and historical data relating to the maps prepared for the project area are presented in Table 28, “Community Map History.” A description of each of the column headings and the source of the date is also listed below.

• Community Name includes communities falling within the geographic area shown on the FIRM, including those that fall on the boundary line, nonparticipating communities, and communities with maps that have been rescinded. Communities with No Special Flood Hazards are indicated by a footnote. If all maps (FHBM, FBFM, and FIRM) were rescinded for a community, it is not listed in this table unless SFHAs have been identified in this community.

• Initial Identification Date (First NFIP Map Published) is the date of the first NFIP map

that identified flood hazards in the community. If the FHBM has been converted to a FIRM, the initial FHBM date is shown. If the community has never been mapped, the upcoming effective date or “pending” (for Preliminary FIS Reports) is shown. If the community is listed in Table 28 but not identified on the map, the community is treated as if it were unmapped.

• Initial FHBM Effective Date is the effective date of the first Flood Hazard Boundary Map

(FHBM). This date may be the same date as the Initial NFIP Map Date.

• FHBM Revision Date(s) is the date(s) that the FHBM was revised, if applicable.

• Initial FIRM Effective Date is the date of the first effective FIRM for the community.

• FIRM Revision Date(s) is the date(s) the FIRM was revised, if applicable. This is the revised date that is shown on the FIRM panel, if applicable. As countywide studies are completed or revised, each community listed should have its FIRM dates updated accordingly to reflect the date of the countywide study. Once the FIRMs exist in countywide format, as Physical Map Revisions (PMR) of FIRM panels within the county are completed, the FIRM Revision Dates in the table for each community affected by the PMR are updated with the date of the PMR, even if the PMR did not revise all the panels within that community.

The initial effective date for the Santa Rosa County FIRMs in countywide format was 12/19/2006.

122

Table 28: Community Map History

Community Name

Initial Identification

Date

Initial FHBM

Effective Date

FHBM Revision Date(s)

Initial FIRM Effective

Date

FIRM Revision Date(s)

Gulf Breeze, City of 06/28/1974 06/28/1974 01/30/1976 09/01/1977

12/19/2006 01/19/2000 06/16/1995 08/03/1992 11/01/1985

Jay, Town of 10/10/1975 10/10/1975 N/A 05/15/1986 12/19/2006

Milton, City of 05/24/1974 05/24/1974 N/A 06/01/1977 12/19/2006 07/18/1985

Santa Rosa, Unincorporated Areas 01/24/1975 01/24/1975 N/A 10/14/1977

12/19/2006 07/17/2002 01/19/2000 07/20/1998 08/03/1992 11/01/1985

SECTION 7.0 – CONTRACTED STUDIES AND COMMUNITY COORDINATION

7.1 Contracted Studies Table 29 provides a summary of the contracted studies, by flooding source, which are included in this FIS Report.

Table 29: Summary of Contracted Studies Included in this FIS Report

Flooding Source

FIS Report Dated

Contractor Number Work

Completed Date

Affected Communities

Beale Creek TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,

Unincorporated Areas

Big Coldwater Creek TBD AECOM EMA-2009-CA-

5937 2018 Santa Rosa County, Unincorporated Areas

Blackwater Bay TBD AECOM EMA-2009-CA-


Blackwater River TBD NWFWMD EMA-2009-CA-

5937 2012 City of Milton, Santa Rosa County, Unincorporated Areas

Bray Mill Creek TBD AECOM EMA-2009-CA-

5937 2012 Santa Rosa County, Unincorporated Areas, Town of Jay

123

Flooding Source

FIS Report Dated


Completed Date


Clear Creek TBD AECOM EMA-2009-CA-5937 2018 Santa Rosa County,


Clear Creek TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,


East Bay TBD AECOM EMA-2009-CA-5937 2015 Santa Rosa County,


East Bay River 11/01/85

Stottler Stagg & Associates and GKY & A ssociates, Inc

EMW-C-0969 1984 Santa Rosa County, Unincorporated Areas


TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,


Escambia Bay TBD AECOM EMA-2009-CA-5937 2015 Santa Rosa County,


Escambia River 11/01/85

Stottler Stagg & Associates and GKY & A ssociates, Inc

EMW-C-0969 1984 Santa Rosa County, Unincorporated Areas

Gulf of Mexico TBD AECOM EMA-2009-CA-5937 2015 Santa Rosa County,


Holley by the Sea TBD AECOM EMA-2009-CA-


Jacobs Creek TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,


Juniper Creek TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,


Long Branch TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,


Malloy Branch TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,


Manning Creek TBD AECOM EMA-2009-CA-


Pace Mill Creek 12/19/06 Dewberry &

Davis LLC N/A 2005 Santa Rosa County, Unincorporated Areas

Pensacola Bay TBD AECOM EMA-2009-CA-

5937 2015 City of Gulf Breeze, Santa Rosa County, Unincorporated Areas

Pond Creek TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,


124

Flooding Source

FIS Report Dated


Completed Date


Pond Creek 12/19/06 Dewberry & Davis LLC N/A 2005

City of Milton, Santa Rosa County, Unincorporated Areas

Reader Creek TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,


Rocky Creek TBD AECOM EMA-2009-CA-5937 2012 Santa Rosa County,


Santa Rosa Sound TBD AECOM EMA-2009-CA-

5937 2015 City of Gulf Breeze, Santa Rosa County, Unincorporated Areas













Yellow River TBD NWFWMD EMA-2009-CA-5937 2012 Santa Rosa County,


7.2 Community Meetings The dates of the community meetings held for this Flood Risk Project and previous Flood Risk Projects are shown in Table 30. These meetings may have previously been referred to by a variety of names (Community Coordination Officer (CCO), Scoping, Discovery, etc.), but all meetings represent opportunities for FEMA, community officials, study contractors, and other invited guests to discuss the planning for and results of the project.

125

Table 30: Community Meetings

Community FIS Report Dated Date of Meeting Meeting Type Attended By

Gulf Breeze, City of

November 1, 1985 August 8, 1979 Initial CCO FEMA, the community, and the study contractor

December 4, 1984 Final CCO FEMA, the community, and the study contractor

January 19, 2000 July 14, 1998 Initial CCO FEMA, the community, and the study contractor

February 12, 1999 Final CCO FEMA, the community, and the study contractor

Milton, City of

May 15, 1985 August 8, 1979 Initial CCO FEMA, the community, and the study contractor


December 19, 2006 Initial CCO None Held

November 10, 2005 Final CCO FEMA, NWFWMD, the Town of Jay, Santa Rosa County, and the State of Florida

Santa Rosa County and Incorporated Areas

December 19, 2006 December 19, 2006 Initial CCO None Held

Final CCO FEMA, NWFWMD, the Town of Jay, Santa Rosa County, and the State of Florida

Santa Rosa County (Unincorporated Areas)

November 1, 1985 August 8, 1979 Initial CCO FEMA, the community, and the study contractor


January 19, 2000 July 14, 1997 Initial CCO FEMA, the community, and the study contractor

February 12, 1999 Final CCO FEMA, the community, and the study contractor

July 17, 2002 June 12, 2001 Initial CCO FEMA, the community, and the study contractor

Final CCO None Held

July 18, 2016 Initial CCO

Final CCO

126

SECTION 8.0 – ADDITIONAL INFORMATION

Information concerning the pertinent data used in the preparation of this FIS Report can be obtained by submitting an order with any required payment to the FEMA Engineering Library. For more information on this process, see www.fema.gov. Table 31 is a list of the locations where FIRMs for Santa Rosa County can be viewed. Please note that the maps at these locations are for reference only and are not for distribution. Also, please note that only the maps for the community listed in the table are available at that particular repository. A user may need to visit another repository to view maps from an adjacent community.

Table 31: Map Repositories

Community Address City State Zip Code

Gulf Breeze, City of City Hall

1070 Shoreline Drive Gulf Breeze FL 32561

Jay, Town of Town Hall

3695 Highway 4 Jay FL 32565

Milton, City of Planning and Development

Department 6738 Dixon Street

Milton FL 32572

Santa Rosa County (Unincorporated Areas)

Santa Rosa County Public Services Department

6051 Old Bagdad Highway Milton FL 32583

The National Flood Hazard Layer (NFHL) dataset is a compilation of effective FIRM databases and LOMCs. Together they create a GIS data layer for a State or Territory. The NFHL is updated as studies become effective and extracts are made available to the public monthly. NFHL data can be viewed or ordered from the website shown in Table 32. Table 32 contains useful contact information regarding the FIS Report, the FIRM, and other relevant flood hazard and GIS data. In addition, information about the State NFIP Coordinator and GIS Coordinator is shown in this table. At the request of FEMA, each Governor has designated an agency of State or territorial government to coordinate that State's or territory's NFIP activities. These agencies often assist communities in developing and adopting necessary floodplain management measures. State GIS Coordinators are knowledgeable about the availability and location of State and local GIS data in their state.


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Table 32: Additional Information

FEMA and the NFIP

FEMA and FEMA Engineering Library website

www.fema.gov/national-flood-insurance-program-flood-hazard-mapping/engineering-library

NFIP website www.fema.gov/national-flood-insurance-program

NFHL Dataset msc.fema.gov

FEMA Region IV Federal Emergency Management Agency 3003 Chamblee Tucker Road Atlanta, GA 30341 (770) 220-5200

Other Federal Agencies

USGS website www.usgs.gov

Hydraulic Engineering Center website

www.hec.usace.army.mil

State Agencies and Organizations

State NFIP Coordinator Steve Martin, CFM Florida Division of Emergency Management 2555 Shumard Oak Boulevard Tallahassee, FL 32399 850-922-5269 [email protected]

State GIS Coordinator Richard Butgereit, GIS Administer Florida Division of Emergency Management 2555 Shumard Oak Boulevard Tallahassee, FL 32399 850-413-9907 [email protected]

SECTION 9.0 – BIBLIOGRAPHY AND REFERENCES

Table 33 includes sources used in the preparation of and cited in this FIS Report as well as additional studies that have been conducted in the study area.

https://www.fema.gov/national-flood-insurance-program-flood-hazard-mapping/engineering-library

https://www.fema.gov/national-flood-insurance-program-flood-hazard-mapping/engineering-library

http://www.fema.gov/national-flood-insurance-program

http://msc.fema.gov/

http://www.usgs.gov/

http://www.hec.usace.army.mil/

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Table 33: Bibliography and References

Citation in this FIS

Publisher/ Issuer

Publication Title, “Article,” Volume, Number, etc. Author/Editor Place of

Publication

Publication Date/

Date of Issuance

Link

BASE1 Santa Rosa County Transportation, Political, Hydrology and Wetland features

Santa Rosa County GIS Milton, FL 09/06/2011 http://www.santarosa.fl.gov/

BASE2 U.G. Geological Survey GIS data

U.S. Geological Survey

Reston, VA 2004 http://www.usgs.gov/

BASE3 Florida Department of Transportation FDOT Imagery

Florida Department of Transportation

Tallahassee, FL 04/18/2013

http://www.dot.state.fl.us/surveyingandmapping/aerialmain.shtm

BASE4 National Geodetic Survey NGS benchmark data

National Oceanic and Atmospheric Administration

Charleston, SC 05/10/2012 http://www.ngs.noaa.gov/

BASE6 US Fish and Wildlife Service National Wetlands Inventory US Fish and

Wildlife Service Falls Church, VA 04/24/2013 www.fws.gov

BASE7 US Census Bureau TIGER Roads US Census Bureau

Washington, D.C 09/13/2011

http://www.census.gov/

FIRM1

Federal Emergency Management Agency

Effective FIRM data for Santa Rosa County, Florida and Incorporated Areas


Washington, D.C. 12/19/2006 https://msc.fema.gov/portal

FIRM3


Effective FIRM data for Okaloosa County, Florida and Incorporated Areas



FIS1


Santa Rosa County, Florida and Incorporated Areas of Flood Insurance Rate Map


Washington, D.C. 12/06/2002 http://www.nwfwmd.state.fl.us/

http://www.santarosa.fl.gov/

http://www.usgs.gov/





http://www.fws.gov/

http://www.census.gov/

https://msc.fema.gov/portal


http://www.nwfwmd.state.fl.us/

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Publisher/ Issuer


Publication

Publication Date/

Date of Issuance

Link

STUDY1


FIRM Panel Layout for Santa Rosa County



STUDY2


Revised and adjusted effective data for Santa Rosa County

URS Corporation Southern

Tampa, FL 07/18/2016 https://msc.fema.gov/portal

STUDY3


Modeling data for Santa Rosa County



STUDY4 NWFWMD GIS Department DEM Breakline features

Northwest Florida Water Management District

Havana, FL 2014 http://www.nwfwmd.state.fl.us/

STUDY4


Modeling data


Tampa, FL 2016 http://www.nwfwmd.state.fl.us/

STUDY4

Northwest Florida Water Management District GIS Department

DEM


Havana, FL 2012 http://www.nwfwmd.state.fl.us/

STUDY5


Modified transition zones URS Corporation Southern









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Publisher/ Issuer


Publication

Publication Date/

Date of Issuance

Link

STUDY6


Detailed coastal analysis using ADCIRC, CHAMP, TWA, CSHORE, and Runup 2.0



STUDY7


Modified transition zones using 2 models



STUDY8


ICPR Modeling for Holley By The Sea Watershed AECOM Tampa, FL 07/18/2016 https://msc.fema.gov/portal

TOPO1


Santa Rosa Mosaic DEM


Santa Rosa County 12/31/2009 http://www.nwfwmd.state.fl.us/





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Documents

SANTA ROSA COUNTY, FLORIDA - Northwest Florida Water ...portal.nwfwmdfloodmaps.com/.../SantaRosa_FIS.pdf · SANTA ROSA COUNTY, UNINCORPORATED AREAS 120274 : Revised Preliminary: July