SPENCER COUNTY, INDIANA
Transcript of SPENCER COUNTY, INDIANA
Spencer County
SPENCER COUNTY, INDIANA AND INCORPORATED AREAS
COMMUNITY COMMUNITY NAME NUMBER *CHRISNEY, TOWN OF 180591 DALE, TOWN OF 180589 GENTRYVILLE,
TOWN OF 180394 GRANDVIEW, TOWN OF 180238 RICHLAND, TOWN OF 180637 ROCKPORT, CITY OF 180239 SANTA CLAUS, TOWN OF 180590 SPENCER COUNTY
(Unincorporated Areas) 180237
*No Special Flood Hazard Areas Identified
PRELIMINARY
Federal Emergency Management Agency
FLOOD INSURANCE STUDY NUMBER
18147CV000A
NOTICE TO FLOOD INSURANCE STUDY USERS
Communities participating in the National Flood Insurance Program have established
repositories of flood hazard data for floodplain management and flood insurance purposes.
This Flood Insurance Study (FIS) report may not contain all data available within the
Community Map Repository. Please contact the Community Map Repository for any
additional data.
The Federal Emergency Management Agency (FEMA) may revise and republish part or all
of this FIS report at any time. In addition, FEMA may revise part of this FIS report by the
Letter of Map Revision process, which does not involve republication or redistribution of the
FIS report. Therefore, users should consult with community officials and check the
Community Map Repository to obtain the most current FIS report components.
Selected Flood Insurance Rate Map panels for this community contain information that was
previously shown separately on the corresponding Flood Boundary and Floodway Map
panels (e.g., floodways, cross sections). In addition, former flood hazard zone designations
have been changed as follows:
Old Zone: New Zone:
A1 through A30 AE
B X
C X
Initial Countywide FIS Effective Date:
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TABLE OF CONTENTS
Page
1.0 INTRODUCTION 1
1.1 Purpose of Study 1
1.2 Authority and Acknowledgments 2
1.3 Coordination 3
2.0 AREA STUDIED 4
2.1 Scope of Study 4
2.2 Community Description 5
2.3 Principal Flood Problems 6
2.4 Flood Protection Measures 7
3.0 ENGINEERING METHODS 7
3.1 Hydrologic Analyses 8
3.2 Hydraulic Analyses 9
3.3 Vertical Datum 10
4.0 FLOODPLAIN MANAGEMENT APPLICATIONS 11
4.1 Floodplain Boundaries 11
4.2 Floodways 12
5.0 INSURANCE APPLICATION 16
6.0 FLOOD INSURANCE RATE MAP 17
7.0 OTHER STUDIES 19
8.0 LOCATION OF DATA 19
9.0 BIBLIOGRAPHY AND REFERENCES 19
FIGURES
Figure 1 - Floodway Schematic 13
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TABLES
Table 1 - CCO Meeting Dates 3
Table 2 – Streams Studied By Detailed Methods 4
Table 3 – Streams Studied By Approximate Methods 4
Table 4 – Scope of Study 5
Table 5 – Population of Incorporated Cities and Towns in Spencer County 6
Table 6 – Summary of Discharges 8
Table 7 – Channel and Overbank Roughness Factors 10
Table 8 – Floodway Data Table 14
Table 9 – Community Map History 18
EXHIBITS
Exhibit 1 - Flood Profiles Panel #s
Little Pigeon Creek 01P-02P
Ohio River 03P-05P
Exhibit 2 - Flood Insurance Rate Map Index
Flood Insurance Rate Map
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FLOOD INSURANCE STUDY
SPENCER COUNTY, INDIANA AND INCORPORATED AREAS
1.0 INTRODUCTION
1.1 Purpose of Study
This Flood Insurance Study (FIS) revises and supersedes the FIS reports and Flood
Insurance Rate Maps (FIRMs) in the geographic area of Spencer County, Indiana,
including the City of Rockport, the Towns of Chrisney, Dale, Gentryville,
Grandview, Richland and Santa Claus, and the unincorporated areas of Spencer
County (hereinafter referred to collectively as Spencer County), and aids in the
administration of the National Flood Insurance Act of 1968 and the Flood Disaster
Protection Act of 1973. This study has developed flood risk data for various areas of
the community that will be used to establish actuarial flood insurance rates and to
assist the community in its efforts to promote sound floodplain management. This
information will also be used by Spencer County to update existing floodplain
regulations as part of the Regular Phase of the National Flood Insurance Program
(NFIP), and by local and regional planners to further promote sound land use and
floodplain development. Minimum floodplain management requirements for
participation in the National Flood Insurance Program (NFIP) are set forth in the
Code of Federal Regulations at 44 CFR, 60.3.
In some states or communities, floodplain management criteria or regulations may
exist that are more restrictive or comprehensive than the minimum Federal
requirements. In such cases, the more restrictive criteria take precedence and the
State (or other jurisdictional agency) will be able to explain them.
Furthermore, the Town of Chrisney does not have special flood hazard areas within
its incorporated limits. However, for the purpose of complete county-wide mapping
of Spencer County, this town is still included in this FIS and FIRMs.
The Digital Flood Insurance Rate Map (DFIRM) and FIS report for this countywide
study have been produced in digital format. Flood hazard information was converted
to meet the Federal Emergency Management Agency (FEMA) DFIRM database
specifications and Geographic Information System (GIS) format requirements. The
flood hazard information was created and is provided in a digital format so that it can
be incorporated into local GIS and be accessed more easily by the community.
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1.2 Authority and Acknowledgments
The sources of authority for this Flood Insurance Study are the National Flood
Insurance Act of 1968 and the Flood Disaster Protection Act of 1973.
Information of the authority and acknowledgements for each of the new studies and
previously printed FIS reports and Flood Insurance Rate Maps (FIRMs) for
communities within Spencer County was compiled and is shown below:
Spencer County
(Unincorporated Areas) The hydrologic and hydraulic analyses for this study
were prepared by the U.S. Geological Survey for the
Federal Insurance Administration for the Federal
Emergency Management Agency (FEMA), under Inter-
Agency Agreement No. IAA-H-17-72, Project Order I-
18-147-000-22. This study, which was completed in
April 1974, covered all significant flooding sources
affecting the unincorporated areas of Spencer County.
Rockport, City of: The hydrologic and hydraulic analyses for this study
were prepared by the U. S. Army Corps of Engineers,
as reported in “Ohio River Profiles” for the Federal
Emergency Management Agency (FEMA). This study,
which was completed in January 1981, covered all
significant flooding sources affecting the City of
Rockport.
Chrisney, Town of: No previous FIS.
Dale, Town of: No previous FIS.
Gentryville, Town of: No previous FIS.
Grandview, Town of: The hydrologic and hydraulic analyses for this study
were prepared by the U. S. Army Corps of Engineers,
as reported in “Ohio River Profiles” for the Federal
Emergency Management Agency (FEMA). This study,
which was completed in January 1981, covered all
significant flooding sources affecting the Town of
Grandview.
Richland, Town of: No previous FIS.
Santa Claus, Town of: No previous FIS.
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New Studies: The hydrologic and hydraulic analyses for approximate
stream reaches of Spencer County were performed by
Morley and Associates, Inc., on behalf of the Indiana
Department of Natural Resources, under Indiana Public
Works Project Number E060020. The Indiana
Department of Natural Resources managed the
production of this study as part of their Cooperating
Technical Partner agreement with the Federal
Emergency Management Agency dated April 29, 2004,
which was defined by the Indiana DNR Mapping
Activity Statement 08-01 dated July 7, 2008 and funded
under agreement number EMC-2008-CA-7017.
Redelineation of the previously effective flood hazard information for this FIS report,
correction to the North American Vertical Datum of 1988, and conversion of the
unincorporated and incorporated areas of Spencer County into the Countywide format
was performed by Morley and Associates, Inc., on behalf of the Indiana Department
of Natural Resources, under Indiana Public Works Project Number E060020. The
Indiana Department of Natural Resources managed the production of this study as
part of their Cooperating Technical Partner agreement with the Federal Emergency
Management Agency dated April 29, 2004, which was defined by the Indiana DNR
Mapping Activity Statement 08-01 dated July 7, 2008 and funded under agreement
number EMC-2008-CA-7017.
1.3 Coordination
The purpose of an initial Consultation Coordinated Officer’s (CCOs) meeting is to
discuss the scope of the FIS. A final CCO meeting is held to review the results of the
study. The dates of the initial and final CCO meetings held for the previously
effective FIS reports covering the geographic area of Spencer County, Indiana are
shown in Table 1. The initial and final CCO meetings were attended by the study
contractor, FEMA (or the Federal Insurance Administration), the Indiana Department
of Natural Resources (IDNR), and the affected communities.
Table 1: CCO Meeting Dates for Pre-Countywide FIS
Community Name Initial CCO Date Final CCO Date
Spencer County * September 1, 1976
(Unincorporated Areas)
Rockport, City of * August 18, 1982
Grandview, Town of * August 18, 1982
*No initial date given in original FIS.
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For this countywide FIS, an initial CCO meeting was held on December 5, 2007, and
was attended by IDNR, the Spencer County Plan Commission, the Indiana 15
Regional Planning Commission, the Chrisney Town Council, the Town of
Grandview, the Town of Dale, the Town of Santa Claus and the City of Rockport.
The results of the countywide study were reviewed at the final CCO meeting held on
--, and attended by representatives of FEMA, IDNR and________. All problems
raised at that meeting have been addressed.
2.0 AREA STUDIED
2.1 Scope of Study
This FIS covers the geographic area of Spencer County, Indiana, including the
incorporated communities listed in Section 1.1.
All FIRM panels for Spencer County have been revised, updated, and republished in
countywide format as a part of this FIS. The FIRM panel index, provided as Exhibit
2, illustrates the revised FIRM panel layout.
Approximate methods of analysis were used to study those areas having a low
development potential or minimal flood hazards as identified during the initial CCO
meeting. For this study, fifteen (15) stream reaches were studied using approximate
methods. The scope and methods of new approximate studies were proposed and
agreed upon by FEMA, the IDNR, and Spencer County.
This FIS update also incorporates the determination of letters issued by FEMA
resulting in map changes (Letters of Map Change, or LOMCs). No Letters of Map
Revision (LOMRs) exist at this time.
Table 2: Streams Studied by Detailed Methods
Little Pigeon Creek Ohio River
Table 3: Streams Studied by Approximate Methods
Anderson River Baker Creek
Blackhawk Creek Buckhorn Creek
Clear Creek Crooked Creek
East Fork Little Pigeon Creek Ferdinand Run
Hawk Run Honey Creek
Hunley Creek Hurricane Creek
Jackson Creek Little Pigeon Creek
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Table 3: Streams Studied by Approximate Methods Cont.
Little Sandy Creek Middle Fork Crooked Creek
Nest Run Sandy Creek
Slough Creek Swinging Creek
Willow Pond Ditch
Table 4: Scope of Study
Stream Limits of Approximate Study
Anderson River Mouth to Perry County Line
Blackhawk Creek Mouth to CR 1050 E
Buckhorn Creek Mouth to about 2000’ upstream of
CR 350 E
Crooked Creek SR 66 to CR 1790 N
Crooked Creek Tributary 24 Mouth to Christmas Lake
East Fork Crooked Creek Mouth to CR 1550 N
East Fork Little Pigeon Creek Mouth to US 231
Hooppole Ditch Mouth to CR 500 N
Huffman Ditch SR 66 to CR400 N
Little Pigeon Creek Hendrickson Road to Warrick
County Line (North)
Little Pigeon Creek Warrick County Line (West) to CR 700E
Little Sandy Creek SR 66 to CR 1000 N
Middle Fork Crooked Creek Mouth to CR 1500 N
Sandy Creek SR 66 to CR 1200 N
Slough Creek SR 66 to 6,000 FT Upstream of SR 66
Stream Limits of Detailed Study
Ohio River Warrick Co Line to Perry Co Line
2.2 Community Description
Spencer County is located in southern Indiana and is bordered by Dubois County to
the north, Spencer County to the east, Hancock County, Kentucky to the southeast,
Daviess County, Kentucky to the south, and Warrick County to the west. The total
land area within the county is approximately 398.7 square miles. The largest city and
county seat is Rockport which is located approximately 140 miles south of
Indianapolis and 48 miles north of Louisville Kentucky. Spencer County is served by
Interstate 64, US Highway 231, State Routes 62, 66, 68, 70, 161, 162, 245, and 545.
The climate in Spencer County ranges from hot and humid in the summertime to cold
during the winter season. Average daytime temperatures during the summer fall
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around 76.9ºF, while winter temperatures average at approximately 34.2ºF.
Precipitation for Spencer County totals an annual amount of 45.67 inches.
According to U.S. Census Data from the year 2010, the population of Spencer County
was reported to be 20,952. Table 5 lists the population of the incorporated areas in
Spencer County.
Table 5: Population of incorporated cities and towns in Spencer County 2010 Census
Community Population
Chrisney, Town of 481
Dale, Town of 1,593
Gentryville, Town of 268
Grandview, Town of 749
Richland, Town of 425
Rockport, City of 2,270
Santa Claus, Town of 2,481
2.3 Principal Flood Problems
Major flooding in Spencer County primarily occurs along the Ohio River, Little
Pigeon Creek, and the tributaries to those streams. The flood of January-February
1937 was the most disastrous for the Ohio River Basin. Excessive and almost
continuous rainfall most of January caused the river to swell to maximum recorded
stages. This flood interrupted communications and transportation for up to a month.
The flood of 1913 was the second largest in the area; due to large storms following
each other very closely. Floods principally occur during the winter and spring
months, but can occur during any season. Generally, two types of storm events cause
flooding. During the winter and spring, storms of moderate intensity and long
duration, coupled with frozen ground, cause flooding to occur. During the summer,
thunderstorms which have high intensities and relatively short durations can cause
floods. Localized flood problems in the incorporated areas are summarized below:
Dale, Town of: Subject to flooding from tributary of Little Pigeon
Creek.
Gentryville, Town of: Subject to flooding from Buckhorn Creek and its
tributary.
Grandview, Town of: Subject to flooding from the Ohio River and its
tributaries.
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Richland, Town of: Subject to flooding from Hooppole Ditch and its
tributary.
Rockport, City of: Subject to flooding from the Ohio River and its
tributaries.
Santa Claus, Town of: Subject to flooding from Crooked Creek and its
tributary.
2.4 Flood Protection Measures
The state of Indiana has set regulations concerning development in a flood plain. The
Indiana Flood Control Act of 1945, as amending, requires that the channels and that
portion of the flood plain known as the floodway be kept free and clear of
interference or obstructions which could restrict the flow rate in a significant manner.
The Act stipulates that the Indiana Flood Plain Management Act of 1973 further
requires that flood plain management regulations adopted after July 1, 1974, meet a
minimum set of standards for the delineation and regulation of flood hazard areas
(Reference 1).
3.0 ENGINEERING METHODS
For the flooding sources studied by detailed methods in Spencer County, 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 once on the
average during any 10-, 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-, 50-, 100-, and 500-year floods, have a 10-, 2-
, 1-, and 0.2-percent 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 1-percent-
annual-chance flood in any 50-year period is approximately 40 percent (4 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.
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3.1 Hydrologic Analyses
Hydrologic analyses were carried out to establish peak discharge-frequency
relationships for each flooding source studied by detailed methods affecting Spencer
County. Table 6 contains a summary of peak discharges for the 10-, 2-, 1-, and 0.2-
percent annual chance floods, where applicable, for each flooding source studied in
detail in Spencer County. Peak discharges in the table were compiled based on
information received from the U.S. Army Corps of Engineers, Louisville District for
Spencer County and incorporated areas.
Table 6. Summary of Discharges
Peak Discharge (CFS)
10% 2% 1% 0.2%
Flooding Source Drainage Area Annual Annual Annual Annual
And Location (Square Miles) Chance Chance Chance Chance
Ohio River
Cannelton L&D 96,700 640,000 800,000 865,000 1,010,000 Mile 720.5
Newburgh L&D 97,670 646,000 805,000 870,000 1,017,000
Upper Gage, Mile 775.8
Standard and accepted hydrologic methods were used to develop discharge data on
the study streams in Spencer County. These data were coordinated with the Indiana
Department of Natural Resources, the Natural Resources Conservation Service
(formally the Soil Conservation Service), the U. S. Geological Survey and the
Louisville District of the U. S. Army Corps of Engineers, through a Memorandum Of
Understanding dated May 6, 1976. Discharge curves for the 10%, 2%, 1%, and 0.2%
annual chance floods were developed for each study stream using several different
procedures and compared for consistency.
The hydrologic analyses for the Ohio River were performed by the U.S. Army Corps
of Engineers. Frequency discharge data for the entire length of the Ohio River are
available based on an analysis conducted by the Ohio River Division of the Corps of
Engineers in Cincinnati, Ohio. Natural discharge-frequency curves for the Ohio
River were developed in accordance with methods presented in papers by Leo R.
Beard, Statistical Methods in Hydrology. Modified discharge-frequency curves, for
the Ohio River, resulted from routing twelve representative floods for the Ohio River
modified by an upstream Corps of Engineers reservoir system. That system included
reservoirs completed or near completion in 1976 and is considered current in 2002.
Data were plotted opposite original flood data on a grid containing a referenced flow
reduction of natural flow and a new best-fit curve drawn. Total reductions were read
from the new curve at selected natural flow frequencies, and subtracted from natural
flows at those frequencies to obtain new modified-flow values.
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Frequency-discharge data for the lower reaches of Little Pigeon Creek were
developed by comparison with Pigeon Creek and Busseron Creek. These three
drainage basins have similar drainage basin characteristics. Streamflow records are
available for Pigeon Creek and Busseron Creek, from which discharge frequencies
were determined using the standard log-Pearson Type III method.
3.2 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. Users should be aware that flood elevations shown on the Flood Insurance
Rate Map (FIRM) represent rounded whole-foot elevations and may not exactly
reflect the elevations shown on the Flood Profiles or in the Floodway Data table in
the FIS report. 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.
Cross sections for the backwater analyses were obtained from a variety of sources
including: physical survey data, IDNR contour mapping, USGS topographic mapping
and local contour mapping. Locations of selected cross sections used in the hydraulic
analyses are shown on the Flood Profiles (Exhibit 1). For stream segments for which
a floodway was computed (Section 4.2), selected cross section locations are also
shown on the FIRM. Cross sections for the Ohio River were determined from detailed
mapping with bathymetry (1” = 600’ with 5-foot contour intervals), developed for
Corps of Engineers - Ohio River navigation studies.
Water-surface elevations for floods of the selected recurrence intervals were
computed through use of the USACE HEC-2 step-backwater computer program. For
the new approximate study reaches, the USACE HEC-RAS program was used. HEC-
RAS is an updated version of the HEC-2 program used to perform step-backwater
analyses. Water-surface elevations of floods of the selected recurrence intervals were
computed through the use of the USACE HEC-2 step-backwater computer program.
For the new approximate study reaches and the Ohio River, the USACE HEC-RAS
(Version 3.1.3) program was used. For Little Pigeon Creek the U. S. Geological
Survey E-431 program was used.
Flood profiles were prepared for all streams studied by detailed methods and show
computed water-surface elevations to an accuracy of 0.5 feet for floods of the selected
recurrence intervals. For this countywide FIS, flood profiles and approved LOMRs
have been consolidated into continuous stream reaches and adjusted to reflect the
current vertical datum as described in Section 3.3. New profiles have been prepared
for the new detailed studies and for the purposes of incorporating the LOMRs
described in Section 2.1 above. A small section of Little Pigeon Creek, from 100 feet
above to 400 feet below the confluence with Baker Creek is within the county
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boundaries; but, no flood profile is shown because this section is flooded by
backwater from the Ohio River.
Channel and overbank roughness factors (Manning’s “n” values) used in the
hydraulic computations were chosen by engineering judgment and were based on
field observations of the stream and floodplain areas. Factors were estimated by field
inspection with the aid of “n” value tables and equations. Channel and overbank
roughness factors used in the detailed studies are summarized by stream in Table 7.
Table 7. Channel and Overbank Roughness Factors
Roughness Coefficients
Stream Main Channel Left Overbank Right Overbank
Ohio River 0.029-0.034 0.05 0.05
Little Pigeon Creek 0.05-0.06 0.04-0.1 0.04-0.1
For new approximate study areas, analyses were based on field inspection and
modeling of the stream reaches using USACE HEC-RAS models. Limited structural
measurements or field surveying was performed. Cross section geometry was derived
from topographic mapping from the 2005 statewide orthophotography project.
Starting elevations were assumed to be normal depth. Starting water-surface
elevations for the Ohio River were obtained using gaged data and known elevation-
discharge relationships at those locations.
The hydraulic analyses for this study were based on unobstructed flow. The flood
elevations shown on the Flood Profiles (Exhibit 1) are thus considered valid only if
hydraulic structures remain unobstructed, operate properly, and do not fail.
3.3 Vertical Datum
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 in use
for newly created or revised FIS reports and FIRMs was the National Geodetic
Vertical Datum of 1929 (NGVD29). With the finalization of the North American
Vertical Datum of 1988 (NAVD88), many FIS reports and FIRMs are being prepared
using NAVD88 as the referenced vertical datum.
All flood elevations shown in this FIS report and on the FIRM are referenced to
NAVD88. Structure and ground elevations in the community must, therefore, be
referenced to NAVD88. It is important to note that adjacent communities may be
referenced to NGVD29. This may result in differences in Base Flood Elevations
(BFEs) across the corporate limits between the communities.
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In this revision, a vertical datum conversion of -0.34 feet was calculated at the
centroid of the county and used to convert all elevations in Spencer county from
NGVD29 to NAVD88 using the National Geologic Survey’s VERTCON online
utility (VERTCON, 2005).
(NGVD29 – 0.34 = NAVD88)
For more information on NAVD88, see the FEMA publication entitled Converting
the National Flood Insurance Program to the North American Vertical Datum of 1988
(FEMA, June 1992), or contact the Vertical Network Branch, National Geodetic
Survey, Coast and Geodetic Survey, National Oceanic and Atmospheric
Administration, Rockville, Maryland 20910 (Internet address
http://www.ngs.noaa.gov).
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 Technical Support
Data Notebook associated with the FIS report and FIRM for this community.
Interested individuals may contact FEMA to access these data.
The horizontal coordinate system used for the production of the digital FIRMs is the
Transverse Mercator projection, Indiana State Plane coordinate system, referenced to
the North American Datum of 1983 and the GRS 1980 spheroid.
4.0 FLOODPLAIN MANAGEMENT APPLICATIONS
The NFIP encourages State and local governments to adopt sound floodplain management
programs. Therefore, each FIS provides 1-percent-annual-chance flood elevations and
delineations of the 1- and 0.2-percent-annual-chance floodplain boundaries and 1-percent-
annual-chance floodway to assist communities in developing floodplain management
measures. This information is presented on the FIRM and in many components of the FIS
report, including Flood Profiles, and the Floodway Data table. Users should reference the
data presented in the FIS report as well as additional information that may be available at the
local map repository before making flood elevation and/or floodplain boundary
determinations.
4.1 Floodplain Boundaries
To provide a national standard without regional discrimination, the 1-percent-annual-
chance flood has been adopted by FEMA as the base flood for floodplain
management purposes. The 0.2-percent-annual-chance flood is employed to indicate
additional areas of flood risk in the community. For each stream studied by detailed
methods, the 1- and 0.2-percent-annual-chance floodplain boundaries have been
delineated using the flood elevations determined at each cross section. Between cross
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sections, the boundaries were interpolated using topographic mapping from the 2005
statewide orthophotography flight.
The 1- and 0.2-percent-annual-chance floodplain boundaries are shown on the FIRM
(Exhibit 2). On this map, the 1-percent-annual-chance floodplain boundary
corresponds to the boundary of the areas of special flood hazards (Zones A, AE, V,
and VE); and the 0.2-percent-annual-chance floodplain boundary corresponds to the
boundary of areas of moderate flood hazards. In cases where the 1- and 0.2-percent-
annual-chance floodplain boundaries are close together, only the 1-percent-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.
For the streams studied by approximate methods, only the 1-percent-annual chance
floodplain boundary is shown on the FIRM (Exhibit 2).
4.2 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 this aspect of floodplain management. Under this
concept, the area of the 1-percent-annual-chance floodplain is divided into a floodway
and a floodway fringe. The floodway is the channel of a stream, plus any adjacent
floodplain areas, that must be kept free of encroachment so that the 1-percent-annual-
chance flood can be carried without substantial increases in flood heights. Minimum
Federal standards limit such increases to 1.0 foot, provided that hazardous velocities
are not produced. The floodways in this study are presented to local agencies as
minimum standards that can be adopted directly or that can be used as a basis for
additional floodway studies.
The State of Indiana, however, per Indiana Code IC 14-28-1 and Indiana
Administrative Code 312 IAC 10, has designated that encroachment in the floodplain
is limited to that which will cause no significant increase in flood height. As a result,
floodways for this study are delineated based on a flood surcharge of less than 0.15
feet. The floodways in this study were approved by the IDNR, and are presented to
local agencies as minimum standards that can be adopted directly or that can be used
as a basis for additional floodway studies.
The floodway presented in this FIS report and on the FIRM was 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
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sections, the floodway boundaries were interpolated. The results of the floodway
computations have been tabulated for selected cross sections (Table 8). In cases
where the floodway and 1-percent-annual-chance floodplain boundaries are either
close together or collinear, only the floodway boundary has been shown.
The area between the floodway and 1-percent-annual-chance floodplain boundaries is
termed the floodway fringe. The floodway fringe encompasses the portion of the
floodplain that could be completely obstructed without increasing the water-surface
elevation of the 1-percent-annual-chance flood more than 0.14 feet at any point.
Typical relationships between the floodway and the floodway fringe and their
significance to floodplain development are shown in Figure 1.
Figure 1: Floodway Schematic
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WIDTH2
SECTION
AREA
MEAN
VELOCITY REGULATORY
WITHOUT
FLOODWAY
WITH
FLOODWAY INCREASE
(FEET) (SQ. FEET) (FT/SEC) (FEET, NAVD) (FEET, NAVD) (FEET, NAVD) (FEET)
OHIO RIVER
A 769.00 19923/6516 311230 2.8 384.6 384.6 384.7 0.1
B 768.00 18723/6084 273386 3.2 384.9 384.9 385.0 0.1
C 767.00 14983/2883 252122 3.5 385.3 385.3 385.4 0.1
D 766.50 13560/2233 234349 3.7 385.5 385.5 385.6 0.1
E 766.00 12386/1700 230461 3.8 385.7 385.7 385.8 0.1
F 765.00 11025/1126 214845 4.0 386.0 386.0 386.1 0.1
G 764.00 13106/2421 237306 3.7 386.3 386.3 386.4 0.1
H 763.00 14622/3517 289489 3.0 386.8 386.8 386.9 0.1
I 762.00 16560/4991 323635 2.7 387.2 387.2 387.3 0.1
J 761.00 15265/7616 298526 2.9 387.5 387.5 387.6 0.1
K 760.00 15224/10776 276429 3.1 387.8 387.8 387.9 0.1
L 759.00 17280/15317 316435 2.7 388.2 388.2 388.3 0.1
M 758.00 20019/17589 397983 2.2 388.5 388.5 388.6 0.1
N 757.00 20833/18507 424787 2.0 388.7 388.7 388.8 0.1
O 756.00 20634/18202 429511 2.0 389.0 389.0 389.1 0.1
P 755.00 19780/17203 383171 2.3 389.1 389.1 389.2 0.1
Q 754.00 18750/15837 394374 2.2 389.4 389.4 389.5 0.1
R 753.00 16640/13975 359960 2.4 389.5 389.5 389.6 0.1
S 752.00 14350/10208 298948 2.9 389.8 389.8 389.9 0.1
T 751.00 14292/6762 272242 3.2 390.0 390.0 390.1 0.1
U 750.00 14022/3300 257558 3.4 390.3 390.3 390.4 0.1
V 749.00 13018/859 256132 3.4 390.7 390.7 390.8 0.1
W 748.00 14798/1009 260589 3.3 391.1 391.1 391.2 0.1
X 747.00 16475/238 302511 2.9 391.6 391.6 391.7 0.1
Y 746.00 17040/1110 304384 2.9 391.9 391.9 392.0 0.1
Z 745.00 14889/1183 267288 3.3 392.1 392.1 392.2 0.1
AA 744.00 13119/1189 248186 3.5 392.4 392.4 392.5 0.1
AB 743.00 11986/506 232572 3.7 392.8 392.8 392.9 0.11 Miles Below Pittsburgh2 Total Width / Width Within County Boundary
WATER SURFACE ELEVATION
TA
BL
E 8
FLOODWAY DATAFEDERAL EMERGENCY MANAGEMENT AGENCY
SPENCER COUNTY, IN
AND INCORPORATED AREAS
FLOODING SOURCE FLOODWAY
CROSS SECTION DISTANCE1
1- PERCENT ANNUAL CHANCE FLOOD
OHIO RIVER
15
WIDTH2
SECTION
AREA
MEAN
VELOCITY REGULATORY
WITHOUT
FLOODWAY
WITH
FLOODWAY INCREASE
(FEET) (SQ. FEET) (FT/SEC) (FEET, NAVD) (FEET, NAVD) (FEET, NAVD) (FEET)
OHIO RIVER
AC 742.00 12073/807 245026 3.6 393.2 393.2 393.3 0.1
AD 741.00 14862/5245 270240 3.2 393.6 393.6 393.7 0.1
AE 740.00 12570/6573 245742 3.5 393.9 393.9 394.0 0.1
AF 739.00 9674/7433 224297 3.9 394.3 394.3 394.4 0.1
AG 738.00 8470/6549 211877 4.1 394.6 394.6 394.7 0.1
AH 737.00 8498/5523 218451 4.0 395.0 395.0 395.1 0.1
AI 736.50 8029/4618 207417 4.2 395.1 395.1 395.2 0.1
AJ 736.00 7776/3375 195127 4.4 395.3 395.3 395.4 0.1
AK 735.50 7302/3012 211572 4.1 395.6 395.6 395.7 0.1
AL 735.00 7237/3201 222253 3.9 395.8 395.8 395.9 0.1
AM 734.50 7134/3091 210576 4.1 396.0 396.0 396.1 0.1
AN 734.00 6810/3398 181846 4.8 396.0 396.0 396.1 0.1
AO 733.50 5535/3410 162262 5.3 396.2 396.2 396.3 0.1
AP 733.00 4168/1520 133707 6.5 396.2 396.1 396.2 0.1
AQ 732.50 4532/201 140256 6.2 396.3 396.3 396.4 0.1
AR 732.00 6748/31 166597 5.2 396.9 396.9 397.0 0.1
AS 731.50 8028/349 188539 4.6 397.3 397.3 397.4 0.1
1 Miles Below Pittsburgh2 Total Width / Width Within County Boundary
WATER SURFACE ELEVATION
CROSS SECTION DISTANCE1
FEDERAL EMERGENCY MANAGEMENT AGENCY
FLOODING SOURCE FLOODWAY1- PERCENT ANNUAL CHANCE FLOOD
TA
BL
E 8
FLOODWAY DATA
SPENCER COUNTY, IN
AND INCORPORATED AREAS OHIO RIVER
16
5.0 INSURANCE APPLICATIONS
For flood insurance rating purposes, flood insurance zone designations are assigned to a community
based on the results of the engineering analyses. These zones are as follows:
Zone A
Zone A is the flood insurance risk zone that corresponds to the 1-percent-annual-chance floodplains
that are determined in the FIS by approximate methods. Because detailed hydraulic analyses are not
performed for such areas, no BFEs or base flood depths are shown within this zone.
Zone AE
Zone AE is the flood insurance risk zone that corresponds to the 1-percent-annual-chance floodplains
that are determined in the FIS by detailed methods. In most instances, whole-foot BFEs derived from
the detailed hydraulic analyses are shown at selected intervals within this zone.
Zone X
Zone X is the flood insurance risk zone that corresponds to areas outside the 0.2-percent-annual-
chance floodplain, areas within the 0.2-percent-annual-chance floodplain, and areas of 1-percent-
annual-chance flooding where average depths are less than 1 foot, areas of 1-percent-annual-chance
flooding where the contributing drainage area is less than 1 square mile, and areas protected from the
1-percent-annual-chance flood by levees. No BFEs or base flood depths are shown within this zone.
17
6.0 FLOOD INSURANCE RATE MAP
The FIRM is designed for flood insurance and floodplain management applications.
For flood insurance applications, the map designates flood insurance risk zones as described in
Section 5.0 and, in the 1-percent-annual-chance floodplains that were studied by detailed
methods, shows selected whole-foot BFEs or average depths. Insurance agents use the zones and
BFEs in conjunction with information on structures and their contents to assign premium rates for
flood insurance policies.
For floodplain management applications, the map shows by tints, screens, and symbols, the 1-
and 0.2-percent-annual-chance floodplains, floodways, and the locations of selected cross
sections used in the hydraulic analyses and floodway computations.
The current FIRM presents flooding information for the entire geographic area of Spencer
County. Previously, separate FIRMs were prepared for each identified flood prone incorporated
community and for the unincorporated areas of the county. Historical data relating to the maps
prepared for each community are presented in Table 9.
18
*Chrisney, Town of N/A None N/A None
Dale, Town of TBD None TBD None
Gentryville, Town of July 11, 1975 None September 16, 1988 None
Grandview, Town of January 23, 1974 July 9, 1976 July 18, 1983 None
Richland, Town of January 3,1975 ** None May 1, 1978 ** None
Rockport, City of December 7, 1973 September 23, 1976 July 18, 1983 None
Santa Claus, Town of TBD None TBD None
Spencer County January 3, 1975 None May 1, 1978 None
(Unincorporated Areas)
*No Special Flood Hazard Areas Identified
**Dates From Spencer County, IN
TA
BL
E 9
COMMUNITY NAME INITIAL IDENTIFICATION
FLOOD HAZARD
BOUNDARY MAP
REVISIONS DATE
FIRM EFFECTIVE DATEFIRM REVISIONS
DATE
COMMUNITY MAP HISTORY
FEDERAL EMERGENCY MANAGEMENT AGENCY
SPENCER COUNTY, IN
(AND INCORPORATED AREAS)
19
7.0 OTHER STUDIES
This FIS report either supersedes or is compatible with all previous studies on streams studied in
this report and should be considered authoritative for purposes of the NFIP.
8.0 LOCATION OF DATA
Information concerning the pertinent data used in the preparation of this study can be obtained by
contacting the Flood Insurance and Mitigation Division, Federal Emergency Management
Agency, Region V, 536 S. Clark Street, 6th
Floor, Chicago, IL 60605
9.0 BIBLIORAPHY AND REFERENCES
1. Federal Emergency Management Agency. Flood Insurance Study, Spencer County, IN
(Unincorporated Areas), November 1, 1977. Washington, D.C.
2. Federal Emergency Management Agency, Flood Insurance Study, City of Rockport, Indiana,
January 18, 1983. Washington, D.C.
3. Federal Emergency Management Agency, Flood Insurance Study, Town of Grandview,
Indiana, January 18, 1983. Washington, D.C.
4. Geobytes City Distance Tool. Accessed at http://www.geobytes.com/CityDistanceTool.htm.
5. U.S. Census Bureau, 2010 Census, accessed at http://www.census.gov/
6. “Historic Census for Indiana Incorporated and Census Designated Places from 1900 to 2000”
STATS Indiana, Indiana Business Research Center, Indiana University Kelley School of
Business, accessed at
http://www.stats.indiana.edu/population/PopTotals/historic_counts_cities.asp
7. Indiana Administrative Code 310 IAC 10 Flood Plain Management accessed at
http://www.in.gov/legislative/iac/T03120/A00100.PDF
8. Indiana Code IC 14-28-1, Flood Control Act, accessed at
http://www.in.gov/legislative/ic/code/title14/ar28/ch1.html
9. Indiana Department of Natural Resources, Division of Water, Coordinated Discharges of
Selected Streams in Indiana, accessed at
http://www.in.gov/dnr/water/surface_water/coordinated_discharges/index.html
10. Indiana Department of Natural Resources, Division of Water, General Guidelines For The
Hydrologic-Hydraulic Assessment Of Floodplains In Indiana, December 2002.
11. Knipe, David, and Rao, A. R. Estimation of Peak Discharges of Indiana Streams by Using the
Log Pearson III Distribution, Purdue University, School of Civil Engineering, Joint
Transportation Research Program, Project No. C-36-620, File No. 9-8-15, 2005.
12. National Oceanic and Atmospheric Administration, National Climatic Data Center, Monthly
Station Normals of Temperature, Precipitation, and Heating and Cooling Days, 1971-2000,
Climatography of the United States No. 81, 2002.
13. U.S. Army Corps of Engineers, Hydrologic Engineering Center ,Computer Program HEC-2
Water Surface Profiles, Davis, California, November 1976.
20
14. U.S. Amy Corps of Enginees, Hydrologic Engineering Center, Computer Program HEC-RAS
River Analysis System, Davis, California, 2004.
15. U.S. Department of the Interior, Geological Survey, Water Resources Investigation 35-75,
Statistical Summaries of Indiana Streamflow Data, February 1976.
16. U.S. Geological Survey, Surface-Water Data for Indiana, Peak-Flow Data for Spencer County.
http://nwis.waterdata.usgs.gov/in/nwis/peak.
320
330
340 340
350 350
360 360
370 370
380 380
390 390
400 400
410 410
6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00
ELE
VA
TIO
N IN
FEET
(N
AV
D 8
8)
STREAM DISTANCE IN MILES ABOVE MOUTH
FED
ER
AL
EM
ER
GEN
CY
MA
NA
GEM
EN
T A
GEN
CY
SP
EN
CER
CO
UN
TY
, IN
AN
D IN
CO
RP
OR
AT
ED
AR
EA
S
FLO
OD
PR
OFI
LES
LIT
TLE
PIG
EO
N C
REEK
01P
A B C D
E
F G H I
J
K
L M N
O P
Q
R
ST
AT
E R
OA
D 1
61
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
CO
UN
TY
BO
UN
DA
RY
340
350
360 360
370 370
380 380
390 390
400 400
410 410
420 420
430 430
19.00 20.00 21.00 22.00 23.00 24.00 25.00 26.00 27.00 28.00 29.00 30.00 31.00 32.00
ELE
VA
TIO
N IN
FEET
(N
AV
D 8
8)
STREAM DISTANCE IN MILES ABOVE MOUTH
FED
ER
AL
EM
ER
GEN
CY
MA
NA
GEM
EN
T A
GEN
CY
SP
EN
CER
CO
UN
TY
, IN
AN
D IN
CO
RP
OR
AT
ED
AR
EA
S
FLO
OD
PR
OFI
LES
LIT
TLE
PIG
EO
N C
REEK
02P
S T
U
V
W
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
LIM
IT O
F D
ET
AIL
ED
ST
UD
Y
260
280
300 300
320 320
340 340
360 360
380 380
400 400
420 420
440 440
770 769 768 767 766 765 764 763 762 761 760 759 758 757
ELE
VA
TIO
N IN
FEET
(N
AV
D 8
8)
STREAM DISTANCE IN MILES BELOW PITTSBURGH
FED
ER
AL
EM
ER
GEN
CY
MA
NA
GEM
EN
T A
GEN
CY
SP
EN
CER
CO
UN
TY
, IN
AN
D IN
CO
RP
OR
AT
ED
AR
EA
S
FLO
OD
PR
OFI
LES
OH
IO R
IVER
03P
A B C D E F G H I J
K L M N
OW
EN
SB
OR
O L
OC
K &
DA
M N
O. 4
6
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
CO
UN
TY
BO
UN
DA
RY
260
280
300 300
320 320
340 340
360 360
380 380
400 400
420 420
440 440
757 756 755 754 753 752 751 750 749 748 747 746 745 744
ELE
VA
TIO
N IN
FEET
(N
AV
D 8
8)
STREAM DISTANCE IN MILES BELOW PITTSBURGH
FED
ER
AL
EM
ER
GEN
CY
MA
NA
GEM
EN
T A
GEN
CY
SP
EN
CER
CO
UN
TY
, IN
AN
D IN
CO
RP
OR
AT
ED
AR
EA
S
FLO
OD
PR
OFI
LES
OH
IO R
IVER
04P
O P Q R S T U V W
X Y Z
U.S
. H
IGH
WA
Y 2
31
CIT
Y O
F R
OC
KP
OR
T
CO
NFLU
EN
CE O
F H
UFF
MA
N D
ITC
HC
OR
PO
RA
TE L
IMIT
S
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
CO
RP
OR
AT
E L
IMIT
S
CIT
Y O
F R
OC
KP
OR
T
240
260
280 280
300 300
320 320
340 340
360 360
380 380
400 400
420 420
744 743 742 741 740 739 738 737 736 735 734 733 732 731
ELE
VA
TIO
N IN
FEET
(N
AV
D 8
8)
STREAM DISTANCE IN MILES BELOW PITTSBURGH
FED
ER
AL
EM
ER
GEN
CY
MA
NA
GEM
EN
T A
GEN
CY
SP
EN
CER
CO
UN
TY
, IN
AN
D IN
CO
RP
OR
AT
ED
AR
EA
S
FLO
OD
PR
OFI
LES
OH
IO R
IVER
05P
AA AB AC AD AE AF AG AH AI AJ AK AL AM
AN AO AP AQ AR AS
TO
WN
OF
GR
AN
DV
I EW
CO
NFL
UEN
CE O
F G
OO
SE C
REEK
CO
RP
OR
AT
E L
IMIT
S
CO
NFLU
EN
CE O
F B
IG S
AN
DY
CR
EEK
CO
NFLU
EN
CE O
F C
RO
OK
ED
CR
EEK
CO
UN
TY
BO
UN
DA
RY
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
CO
RP
OR
AT
E L
IMIT
S
TO
WN
OF
GR
AN
DV
I EW