Appendix J Format and Specifications for Flood Insurance Study Reports The Federal Emergency Management Agency (FEMA) has established a concise, standardized format for the presentation of the facts, figures, and results of a Flood Map Project - the Flood Insurance Study (FIS) report. This Appendix includes guidance for the Mapping Partner that performed the detailed hydrologic and/or hydraulic analyses to follow in preparing and submitting content to be included in the FIS report. This Appendix also includes detailed FIS report preparation guidance for the Mapping Partner that reviews and processes the draft materials and prepares the Preliminary and Final versions of the FIS report, including submittal of the report to the FEMA Map Service Center (MSC). A sample, completed FIS report for a single community is included in Section J.4 for guidance. J.1 Submittal Content for Flood Insurance Study Reports The Mapping Partner that performed the detailed hydrologic and/or hydrologic analyses for the Flood Map Project (hereinafter referred to as the submitting Mapping Partner) shall submit only the information outlined below. Unless specifically requested to do so by the FEMA Lead for the Flood Map Project (usually, the Regional Project Officer or the Project Officer at FEMA Headquarters), the submitting Mapping Partner shall not draft a complete FIS report. The information submitted will be used by the Mapping Partner that reviews the draft materials provided by the submitting Mapping Partner and prepares the Preliminary and Final versions of the FIS report (hereinafter referred to as the processing Mapping Partner). If FEMA published an effective FIS report for the community, the submitting Mapping Partner will not need to submit certain information. The submitting Mapping Partner is to limit the submitted information for each section to information pertinent to the current Flood Map Project and to those events that have occurred since the date of the effective FIS report (e.g. new population information, major flood event). The processing Mapping Partner shall include the new information in the Preliminary and Final versions of the FIS report as discussed in Subsection J.2. The requirements to be followed by the submitting Mapping Partner are summarized in Subsections J.1.1 through J.1.7. [February 2002] J.1.1 Section 1.0, Introduction For Subsection 1.1, Purpose of Study, the submitting Mapping Partner shall include the following information: * Community name; * County name; and * State name. For Section 1.2, Authority and Acknowledgments, the submitting Mapping Partner shall include the following information: * Name(s) of Mapping Partner(s) that performed flood hazard analyses for Flood Map Project; * Interagency Agreement Number or Contract Number; * Completion date (month and year); * Name and address of base map provider/agency; and * Base map compilation source, scale, and date; coordinate system; projection; datum; any modifications to the base map source; and any restrictions on the release of base map data. For Subsection 1.3, Coordination, the submitting Mapping Partner shall include the following information: * Initial Consultation and Coordination Officer (CCO) meeting date, attendees, and agencies represented; * Intermediate CCO meeting date, attendees, and agencies represented (if applicable); and * Contacts made for purposes of acquiring information. [February 2002] J.1.2 Section 2.0, Area Studied For Subsection 2.1, Scope of Study, the submitting Mapping Partner shall include the following information: * Areas excluded from the study, as well as areas of extraterritorial jurisdiction; * Names of flooding sources studied using detailed methods, listed in the same order as they appear in the Flood Profiles; * Limits of detailed study for flooding sources studied partially using approximate methods; * Names of Flooding sources studied by approximate methods; and * Flooding sources on which the study was terminated, where the 1-percent-annual-chance floodplain permanently narrowed to less than 200 feet wide or for which the detailed study was ended where the drainage area was less than 1 square mile, when applicable. For Subsection 2.2, Community Description, the submitting Mapping Partner shall include the following information: * General description of the community's location within the county and state; * Surrounding communities and their locations with respect to the subject community; * Other nearby large cities and their locations relative to the community; and * A brief description of the community. The brief description may include population and census reference; patterns of residential and commercial development; the extent and nature of floodplain development; natural features that affect flood hazards in the community; and sufficient description of climatic, physiographic, and land use factors to support the discussion of flood problems that follows in Subsection 2.3. For Subsection 2.3, Principal Flood Problems, the submitting Mapping Partner shall include the following information: * Discharges and recurrence intervals of major floods; * Locations (city and state) of all stream gages for studied streams; * Any factors that aggravate flood problems; and * Photographs of flooding, flood-control structures, and other flood-related subjects (with locations of photographs noted). For Subsection 2.4, Flood Protection Measures, the submitting Mapping Partner shall include the following information: * A description of all flood protection structures and floodplain management measures used to reduce potential flood damage; * A description of all dams, including those affecting the community that lie outside the community; * A description of dams within the community used for purposes other than flood control; and * A description of levees and whether they meet the FEMA 3-foot freeboard requirement and any other provisions of Section 65.10 of the National Flood Insurance Program (NFIP) regulations. In the description of levees, the submitting Mapping Partner shall identify any levees that have been certified by another Federal agency to provide flood protection, although they may not meet FEMA criteria, and the protected reaches. [February 2002] J.1.3 Section 3.0, Engineering Methods For Subsection 3.1, Hydrologic Analyses, the submitting Mapping Partner shall include the following information: * A description of the hydrologic analyses, including the computer model used, for all flooding sources studied using detailed methods; * A Summary of Discharges Table, providing a summary of drainage area-peak discharge relationships for the streams studied by detailed methods; and * A Summary of Stillwater Elevations Table, providing a summary of 10-percent-annual- chance (10-year), 2-percent-annual-chance (50-year), 1-percent-annual-chance (100-year), and 0.2-percent-annual-chance (500-year) flood elevations at all lakes and ponds studied using detailed methods and along streams in cases where elevations would create a flat profile along the studied reach. For the Summary of Discharges Table, drainage areas for each stream are to be listed in descending order. Streams are to be listed in the same order as they appear in the Flood Profiles. A sample Summary of Discharges Table is provided in the sample report in Section J.4. For the Summary of Stillwater Elevations Table, flooding sources are to be listed alphabetically; locations are to be listed from upstream to downstream. A sample Summary of Stillwater Elevations table is provided in the sample report in Section J.4.. For Subsection 3.2, Hydraulic Analyses, the submitting Mapping Partner shall include the following information: * A description of the method used for developing cross sections for all streams studied by detailed methods; * A description of the method used for determining the dimensions of hydraulic structures; * A description of the method used for assigning channel roughness factors (Manning's "n") and the "n" values for all streams studied by detailed methods (channel and overbank areas); * A description of the method used for obtaining water-surface elevations for all streams studied by detailed methods, including the computer model used; * A description of the method used for obtaining starting water-surface elevations for all streams studied by detailed methods; * A description of the method used for studying wave height and wave runup; lacustrine, ice jam, and alluvial fan flooding; and areas of shallow flooding (where applicable), including the computer model used; * Transect Descriptions, when applicable, that includes the transect number, location, 1- percent-annual-chance stillwater elevation, and maximum 1-percent-annual-chance wave elevation; * A description of the hydraulic analyses for approximate flooding sources, if performed; * Transect Data Table, when applicable, that includes the flooding source (with the affected transects); 10-, 2-, 1-, and 0.2-percent-annual-chance stillwater elevations; zone designation; and Base Flood Elevation (BFE); * Transect schematic, when applicable; and * Transect Location Map, when applicable. For Section 3.3, Vertical Datum, the submitting Mapping Partner shall include the vertical datum and releveling dates, if any, and the conversion factors, if any. [February 2002] J.1.4 Section 4.0, Floodplain Management Applications For Subsection 4.1, Floodplain Boundaries, the submitting Mapping Partner shall include information on the following: * All source maps used, including scale, contour interval, date of map, and type of map (e.g., topographic, compiled from aerial photographs) or information used to create the work map; and * All maps or methods used to delineate floodplain boundaries for flooding sources studied by approximate methods. For Subsection 4.2, Floodways, the submitting Mapping Partner shall include the following information when floodways are computed: * Names of all streams for which regulatory floodway widths extend beyond the corporate or county limits; * Names of all streams affected by backwater from other streams; * A description of the method(s) used for computing regulatory floodway(s); * Floodway Data Table; * Floodway schematic; * Reason(s) why regulatory floodways were not computed and delineated for certain streams or portions of streams; and * A description of any unusual procedures, such as State-imposed or locally imposed surcharge limits of less than 1.0 foot for regulatory floodway. [February 2002] J.1.5 Section 5.0, Insurance Application For Section 5.0, the submitting Mapping Partner does not need to submit any information, unless specifically directed to prepare a complete FIS report. Section 5.0 shall include the standard language that appears in the sample FIS report in Section J.5. [February 2002] J.1.6 Section 6.0, Flood Insurance Rate Map For Section 6.0, the submitting Mapping Partner does not need to submit any information, unless specifically directed to prepare a complete FIS report. Section 6.0 shall include the standard language that appears in the sample FIS report in Section J.5. [February 2002] J.1.7 Section 7.0, Other Studies For Section 7.0, the submitting Mapping Partner shall identify and reference all FEMA studies and restudies for contiguous communities and any other published reports or available data covering flooding sources in the community or county. All disagreements and discrepancies shall be noted and/or resolved. [February 2002] J.1.8 Section 8.0, Location of Data For Section 8.0, the submitting Mapping Partner does not need to submit any information, unless specifically directed to prepare a complete FIS report. Section 8.0 shall include the standard language that appears in the sample FIS report in Section J.5 as well as the address for the FEMA RO for the state in which community is located. [February 2002] J.1.9 Section 9.0, Bibliography and References For Section 9.0, the submitting Mapping Partner shall list references with complete information. For all references, the author or originating agency, title, date of publication or distribution, and place of publication (Washington, DC not needed for Federal agency publications) shall be included. For map references, the map scale and contour interval (as applicable) shall be included. [February 2002] J.1.10 Exhibit 1, Flood Profiles For Exhibit 1, Flood Profiles, new Flood Profiles or revised Flood Profiles for all flooding sources studied by detailed methods are to be listed. See Subsection J.2.3.1 for Flood Profile specifications. [February 2002] J.2 Preparation of Flood Insurance Study Reports The FIS report shall include cover, text, tables (as applicable), photographs (if available), floodway schematic (if applicable), transect schematic (if applicable), transect location map (if applicable), and Flood Profiles (if applicable). The processing Mapping Partner shall follow the specifications in this section in preparing Preliminary and Final versions of new and revised FIS reports. Requirements for format and text content, standard paragraphs and language, graphic specifications, and organization are summarized in the subsections that follow. [February 2002] J.2.1 Format and Text Content Specifications The sample FIS report located in Section J.4 presents the overall format and sections required to produce an FIS report for final printing and is supplemented by Figures J-1 through J-15 at the end of this Appendix. The content of the sample single-jurisdiction report is fictional. The sample presents an original report that has been revised twice by adding an additional section to the report. The sections, subsections, paragraphs and language required for every FIS report appear in bold-faced type. The language of the specific content within the sections can be used as guidance. The subsections below present the different formats of FIS reports and list the additions or changes to the sample report required for each. Additional guidance and requirements for the Mapping Partner that prepares the FIS report in final form for FEMA (hereinafter referred to as the processing Mapping Partner) are provided below. * The margins of all pages are to be approximately 1 inch to allow for binding of the printed FIS report. * The final camera-ready text pages are to be typed, single-spaced, on 8-1/2" x 11", good- quality non-grain paper. Negatives of the text pages are not required for camera-ready deliverables submitted to the MSC for publication by the U.S. Government Printing Office (GPO). * Most of the required tables may be typed as part of the text; hence, they require no graphics preparation. They may be produced in a landscape or portrait format, with preference given to the best presentation based on the size of the tables. The sample report in Section J.4 and Figures J-7 through J-15 at the end of this Appendix provide guidance on table presentation. In some cases, it may be appropriate for the processing Mapping Partner to use the same graphic format used for the effective FIS report materials for consistency of presentation. * The format of Section 9.0, Bibliography and References, in the sample report is one method that may be used to present the references within the body of the FIS report and in Section 9.0. Other industry-accepted formats may be used as long as the application of the format is consistent within the FIS report. If an FIS report is revised or the FIS report is revised by Addendum (see Subsection J.2.1.6), the format used for the effective FIS report must be followed. * The opening page of all FIS reports is the Notice to Flood Insurance Study Users. When the results of a Flood Map Project are issued in Preliminary form for community review, FIS reports are to include the following note at the bottom of that page if any unchanged components have been omitted from the Preliminary version of the FIS report: The Preliminary FIS report does not include unrevised Floodway Data Tables or unrevised Flood Profiles. These unrevised components will appear in the final FIS report. The processing Mapping Partner shall remove this note before the FIS report is submitted to the MSC for printing by GPO. * If the vertical datum used for the Flood Map Project or map revision is North American Vertical Datum of 1988 (NAVD88) or if the vertical datum was changed from National Geodetic Vertical Datum of 1929 (NGVD29) to NAVD88, all FIS report components including, but not limited to, the Floodway Data Table and the Flood Profiles, must reflect the correct datum title. [February 2002] J.2.1.1 Map Initiatives Format The FEMA Map Initiatives Format is used to present all flood hazard information on the Flood Insurance Rate Map (FIRM), including floodplain boundary delineations, floodway boundary delineations, zone labels, BFEs, and cross sections. When a FIRM is prepared in the Map Initiatives Format, some specific text changes shall be made to the FIS report. Guidance on when an FIS report is to be prepared in the Map Initiatives Format is provided below. [February 2002] First-Time Flood Insurance Study Report The processing Mapping Partner shall use the Map Initiatives Format for a single-jurisdiction FIS report for a community that does not have an effective FIS report. The sample FIS report in Section J.4 (without the additional revisions section) presents the information requiremed for a first-time FIS report prepared in the Map Initiatives Format. [February 2002] Conversion of Standard Format to Map Initiatives Format The processing Mapping Partner shall use the Map Initiatives Format also when converting the FIS report from the Standard Format; that is, to combine flood hazard and regulatory floodway data previously included on FIRMs and Flood Boundary and Floodway Maps (FBFMs) into a single FIRM format. Requirements concerning format and organization are provided below. The processing Mapping Partner shall include the following information at the end of the Notice to Flood Insurance Study Users included in the sample report in Section J.4: 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(s) New Zone Al through A30 AE VI through V30 VE B X C X The processing Mapping Partner shall complete and substitute the following paragraph for the first paragraph in Subsection 1.1 of the FIS report: This Flood Insurance Study (FIS) report has been prepared to revise and update a previous FIS report/Flood Insurance Rate Map (FIRM) for the [Full Community Name]. This information will be used by [Community Name] to update existing floodplain regulations as part of the Regular Phase of the National Flood Insurance Program (NFIP). The information will also be used by local and regional planners to further promote sound land use and floodplain development. [February 2002] J.2.1.2 Partial Map Initiatives Format For some FIS reports, FEMA may direct the processing Mapping Partner to prepare the FIRM and FIS report in the Partial Map Initiatives Format. That is, FEMA may request that the processing Mapping Partner prepare only certain FIRM panels and certain portions of the FIS report in the Map Initiatives Format. Specific requirements for the format and organization of an FIS report prepared in the Partial Map Initiatives Format are provided below. The processing Mapping Partner shall include the following information at the end of the standard Notice to Flood Insurance Study Users included in the sample report in Section J.4: 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 and cross sections). In addition, former flood insurance risk zone designations have been changed as follows. Old Zone(s) New Zone A1-A30 AE V1-V30 VE B X C X Initial Effective Date: January 20, 1990 Revised Dates: April 15, 1994 - to change Special Flood Hazard Areas, to change Base Flood Elevations, to change zone designations, and to add Special Flood Hazard Areas, dated May 13, 1990, from Fulton County, Pennsylvania. August 22, 1997 This additional information for the Notice to Flood Insurance Study Users provides for the addition of the Reason for Revision with the revision dates. The processing Mapping Partner shall use the addition when room is limited on the FIRM panel. The most recent date represents the "current" revision, and the reasons for this revision are those that appear on the FIRM legend. See Appendix K of these Guidelines for a complete discussion of map dates in the legend. [February 2002] J.2.1.3 Countywide Format The Countywide Format is used to present a unified study of flood hazards across community boundaries within a county. The processing Mapping Partner generally shall follow the sample report provided in Section J.4; however, several changes shall be made to the standard wording and tables. Those changes are presented below in the order of their appearance in the FIS report. Subsection 1.1, Purpose of Study The processing Mapping Partner shall complete and substitute the following paragraph for the first paragraph: This Flood Insurance Study (FIS) revises and supersedes the FIS reports and/or Flood Insurance Rate Maps (FIRMs) [/Flood Boundary and Floodway Maps] in the geographic area of ______________ County, State, including the [Complete Names of Incorporated Communities, in Alphabetical Order] and unincorporated areas of __________ County (hereinafter referred to collectively as _________ 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. This information will also be used by ________ 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 NFIP are set forth in the Code of Federal Regulations at 44 CFR, 60.3. Subsection 2.1, Scope of Study The processing Mapping Partner shall complete and substitute the following sentence for the first sentence: This FIS covers the geographic area of ___________ County, [State]. [February 2002] Section 6.0, Flood Insurance Rate Map The processing Mapping Partner shall complete and add the following paragraph at the end of the section: The current FIRM presents flooding information for the entire geographic area of ________ County. Previously, separate Firms were prepared for each identified floodprone incorporated community and the unincorporated areas of the county. Historical data relating to the maps prepared for each community are presented in Table ___. The processing Mapping Partner also shall add a Community Map History Table in this section. Format and specifications for this table are presented in Figure J-15 at the end of this Appendix. [February 2002] J.2.1.4 Existing Data Studies and Existing Data Restudies Existing Data Studies and Existing Data Restudies are processed when analyses that are conducted independently for purposes other than the NFIP are submitted to update flood hazards shown on NFIP maps. For Existing Data Studies and Existing Data Restudies, the processing Mapping Partner shall produce the FIS reports in the format provided in the sample report in Section J.4, with the name of the agency that is the source of data cited in Subsection 1.2 of the FIS report. [February 2002] J.2.1.5 Flood Insurance Study Report/Flood Insurance Rate Map Combinations For small-scale Flood Map Projects and map revisions, especially those that include single-panel FIRMs, the FEMA RPO, PO or his/her designee may direct the processing Mapping Partner to print the FIS report directly on the FIRM panel. Additional information on this mapping format is provided in Appendix K. Interested parties may order an example of this format from the FEMA MSC by calling 1-800-358-9616. [February 2002] J.2.1.6 Revisions by Addendum If FEMA directs the processing Mapping Partner to revise an FIS report but not reformat it, the processing Mapping Partner shall ensure that the format, organization, and content of the report follow that of the effective FIS report, with some exceptions. The processing Mapping Partner shall take the most cost-effective approach to updating the FIS report; the minimum work required is the creation of an addendum, or additional section, that shall be placed at the end of the FIS report. This section, Revisions Description, shall appear as Section 9.0 for reports prepared in Standard Format or as Section 10.0 for reports prepared in Map Initiatives Format. The Revisions Description section is to provide information regarding the significant revisions that were made since the FIS report was last printed. The processing Mapping Partner shall include a subsection for each revision, and shall ensure that the subsections are numbered consecutively (e.g., 9.1, 9.2, for reports prepared in Standard Format; 10.1, 10.2, for reports prepared in Map Initiatives Format). Samples of the added section can be found in the sample report in Section J.4. If the addendum format is used, the processing Mapping Partner shall include the information below in the "Notice to Flood Insurance Study Users" in addition to the information found in the sample FIS report. The processing Mapping Partner shall substitute Section 10.0 with Section 9.0 and Sections 1.0 through 9.0 with Sections 1.0 through 8.0 if the effective FIS report was prepared in the Standard Format. This FIS report was revised on [add new effective date]. Users should refer to Section 10.0, Revisions Description, for further information. Section 10.0 is intended to present the most up-to-date information for specific portions of this FIS report. Therefore, users of this FIS report should be aware that the information presented in Section 10.0 supersedes information in Sections 1.0 through 9.0 of this FIS report. [February 2002] J.2.2 Graphic and Table Elements The requirements for the graphic and table elements of an FIS report are summarized in Subsections J.2.2.1 through J.2.2.7. Graphic examples of report elements are provided in the sample report in Section J.4 and in Figures J-1 through J-5 at the end of this Appendix. [February 2002] J.2.2.1 Cover The processing Mapping Partner shall use the existing cover of the FIS report if it was prepared according to the requirements below. If the processing Mapping Partner creates a new FIS report, the cover need not include the outline of the subject county and State. The processing Mapping Partner shall provide the final camera-ready cover on 9" x12" contact negative film. The following are requirements for the presentation of the final FIS report cover: * Where applicable, the effective date or revised date (matching that shown on the FIRM) is to be shown. * The legal name of the community (e.g., City of _________, Township of ______), the County name, and the State name is to be shown. The legal name may be obtained by requesting a letterhead from the community. * If the FIS report is to be printed in two or more volumes, a separate cover is to be prepared for each volume, indicating the appropriate number of the volume. See Figures J-1, J-2, and J-3 at the end of this Appendix for presentation requirements. * Countywide FIS report covers are to include a list of the names and community identification numbers of the county and all incorporated communities, including non- floodprone communities. [February 2002] J.2.2.2 Vicinity Map If the effective FIS report for a subject community includes a Vicinity Map, the processing Mapping Partner shall remove the Vicinity Map when preparing the revised FIS report. If a new FIS report is created, the processing Mapping Partner shall not create a Vicinity Map. [February 2002] J.2.2.3 Transect Location Map For Flood Map Projects and map revisions that include wave height or wave runup analyses, the locations of transects used in the analyses are to be shown on a Transect Location Map. When a Transect Location Map is required, the processing Mapping Partner shall prepare the frame according to the specifications given in the sample FIS report in Section J.4. The processing Mapping Partner shall prepare the final Transect Location Map on 9" x 12" contact negative film. [February 2002] J.2.2.4 Flood Photographs If flood photographs are to be used in the FIS report, the processing Mapping Partner shall submit the screened photographs set in their correct locations in the FIS report. The processing Mapping Partner may prepare the photographs in positive or negative camera-ready form. [February 2002] J.2.2.5 Schematics The processing Mapping Partner shall include a floodway schematic and/or a transect schematic, when applicable. The processing Mapping Partner shall refer to the sample report in Section J.4 and to Figure J-5 at the end of this Appendix for requirements for the schematics. [February 2002] J.2.2.6 Floodway Data Table A Floodway Data Table is to be created for each flooding source for which a regulatory floodway has been designated on the FIRM or FBFM. Floodway data are to be shown for each cross section shown on the FIRM or FBFM. Cross-section labels must be consistent with the FIRM, FBFM, and Flood Profiles. The water-surface elevations in the "Regulatory" column must be identical to the elevations shown on the Flood Profiles. The "Without Floodway" column must contain the natural 1-percent-annual-chance (100-year) water-surface elevations of streams computed without consideration of backwater from other flooding sources. These two columns will contain identical elevations except in confluence situations where regulatory elevations are determined by another flooding source. Cross-section data may be shown for areas of backwater flooding; however, elevations in the "Without Floodway" column of the Floodway Data Table must be footnoted as follows: Elevation Computed Without Consideration of Backwater Effects From (Source of Flooding) The words "Backwater Effects" are to be replaced with "Tidal Effects," "Overflow Effects," "Ice Jam Effects," or "Storm Surge Effects," to reference the appropriate flooding situation. Where a rise in energy grade has been used to determine the regulatory floodway, the computed change in water-surface elevation must be shown, even though these changes may be small. When negative surcharges are encountered, the "Increase" column must be shown as 0.0, and the value in the "With Floodway" column must be the same as the value in the "Without Floodway" column. In general, when bridge cross-section data are included in the table, only the data for the cross section at the upstream face of the bridge is to be provided on the Floodway Data Table. The regulatory floodway width values shown on the Floodway Data Table must be rounded to the nearest whole foot. When a part of a regulatory floodway is outside the corporate or county limits and the width within the corporate or county limits is not shown, the "Width" column must be footnoted as follows: "This Width Extends Beyond the Corporate/County Limits." When both the total width and the width within the corporate/county limits are known, the "width" column must be footnoted as follows: "Width/Width Within Corporate (County) Limits." The specifications for the Floodway Data Table are provided in the sample report in Section J.4. [February 2002] J.2.2.7 Flood Insurance Zone Data Table For revised FIS reports that are kept in the Standard Format, flood insurance zone data are to be tabulated at the direction of the FEMA RPO, PO, or his/her designee. Flood insurance zone data are to be included in the appropriate format for each flooding source studied by detailed methods. However, backwater reaches of a tributary stream are not to be listed when the main stream has also been studied and zone data are listed for it in the table. The specifications for the Flood Insurance Zone Data Table are provided in Figure J-15. In situations where the FIRM is being produced, in whole or in part, in the Map Initiatives Format, the processing Mapping Partner shall remove the Flood Insurance Zone Data Table from the FIS report. [February 2002] J.2.3 Flood Profiles The processing Mapping Partner may use the Flood Profiles generated by the submitting Mapping Partner for final publication if they are technically accurate and legible and they meet the standards and requirements summarized in Subsection J.2.3.1 [February 2002] J.2.3.1 Flood Profile Standards and Requirements The submitting Mapping Partner and processing Mapping Partner shall ensure that the Flood Profiles meet the following standards and requirements: * The Flood Profiles for each stream studied by detailed methods shall be drawn in a standard format, using the format, symbol, and type specifications shown on the Flood Profile in the sample report in Section J.4. If a main stream has backwater effects on a tributary stream, and the flood elevations computed for the main stream are revised, the Flood Profiles for the tributary stream shall be revised accordingly. * Flood Profiles shall not be plotted for more than one flooding source on each panel, with one exception. When a main stream goes by one name to a point where it is formed by the confluence of two small tributary streams, one of the tributary streams shall be selected as a logical continuation of the main stream. The Flood Profile shall then continue, uninterrupted, up the tributary. The Flood Profile panel shall show both the stream names in the title block and indicate the point where the name change occurs. The main stream stationing and cross-section sequencing are to continue up the tributary stream. Each stream shall be treated separately in the text and tables. Flood Profiles shall be continuous for the entire stream length studied. * When the Flood Profiles are prepared for the first time, or existing Flood Profiles are revised, the 10-, 2-, or 0.2-percent-annual-chance flood lines shall not be included. The water-surface profiles of the 1-percent-annual-chance flood and the channel bottom (streambed) or hydraulic base line only are to appear. * Breaks in the Flood Profile shall not occur for stream segments passing through areas not included or where the stream and floodplains leave and return to the community. Flood Profiles are also required for those watercourse segments that may not lie within the community, but do contribute to the flood inundation within the community. Profile limits are to include areas where the stream has left the community, but flood inundation continues. The processing Mapping Partner shall label those limits that are located outside the community as "Limit of Flooding Affecting Community." * On the Flood Profiles for tributary streams, the 1-percent-annual-chance flood backwater from the main watercourse or water body shall be labeled as "Backwater From (Main Stream Name)." * All drawdowns shall be eliminated from the Flood Profiles. * Any well-documented high-water marks of past major floods that are discovered during the reconnaissance shall be shown and referenced on the Flood Profiles. Additional guidance regarding scale, cross sections, physical features, restudied streams, and reach and zone labels is provided in the subsections below. [February 2002] Scale An elevation scale (vertical) of 1 inch equals 1, 2, 5, 10, or 20 feet is to be used. Use of non-whole- foot scales (e.g., 1 inch = 2.5 feet) shall be approved by the FEMA RPO, PO, or his/her designee. Elevations shall be shown on the left side of the grid at 1-inch intervals within the profile elevation range. Elevations need not be shown on the right side of the grid. The profile plots shall agree to within 1/20 inch of the 1-percent-annual-chance regulatory flood elevations provided in the Floodway Data Table. The stream distance scale that is used shall be chosen so that the profile measures at least 3 inches in length and the average slope across the profile page does not exceed 35 degrees. When determining scales, the Mapping Partner shall consider the total number of Flood Profiles that will be created. A horizontal scale of 1 inch equals 100, 200, 400, 500, 1,000, or 2,000 feet is preferred. The horizontal scale shall be labeled at 1-inch intervals along the bottom edge of the grid and legend box. The use of miles, and fractions thereof, is to be avoided except for major flooding sources where a reference system in miles has already been established. However, the units for any one flooding source shall be consistent. Stationing notation (i.e., 100 + 00) is to be converted into conventional feet measurement. Stationing is to be referenced from a physical location such as a confluence or structure. Corporate limits are only be used as a last resort for Flood Profile stationing. Downstream elevations are to begin on the left edge of the grid. Stream distance is measured along the stream channel centerline or some other hydraulic base line as defined and delineated on the work maps submitted by the submitting Mapping Partner. Distance and elevation units used on a Flood Profile must be consistent with the units provided in the computer printout and with the units used on the Floodway Data Table. [February 2002] Cross Sections Flood Profile cross sections must be plotted at distances that are consistent with tabular data and work map locations. Cross sections for each stream are to be labeled in alphabetical sequence, beginning at the downstream study limit. For each stream, the labels are to begin with A, B, C, and continue to Y, Z, AA, AB, ... AZ, BA, BB, BC, and so forth. Cross-section sequences must not be carried over from one stream to another unless the hydraulic model is continuous from one stream to another. Cross-section labels are to be shown within hexagonal shapes; when close spacing necessitates, hexagons are to be stacked, as shown on the sample Flood Profile in the sample FIS report in Section J.4. The location of the cross section indicated by the placement of the hexagon must not deviate more than 0.05 inch from the location presented on the Floodway Data Table. For short stream segments that meander beyond the detailed study limits, and for stream segments for which no regulatory floodway is computed, selected sequentially labeled cross sections may be shown on the Flood Profile. [February 2002] Physical Features All hydraulic structures, points of confluence, corporate limits, and other pertinent information must be indicated on the Flood Profiles. Points of confluence for entering tributaries are to be labeled as "Confluence with (Stream Name)." For bridges, top of road (TOR), and low steel (LS) are to be represented by the conventional symbol, "I," where TOR is represented by the upper horizontal bar, LS by the lower bar, and the center of the structure by the vertical bar. For high-level bridges where the symbol cannot be shown on the Flood Profile, TOR and LS elevations are to be indicated. For culverts, the symbol is to represent the overburden. The culvert pipe is assumed to be the open area between the streambed and the bottom of the overburden. [February 2002] Restudied Streams In preparing Flood Profiles for restudied streams, the processing Mapping Partner shall maintain the existing format. For example, the processing Mapping Partner shall use the horizontal and vertical scales used in the effective FIS report. Stationing notation and datum reference must be consistent with effective Flood Profiles to perform any modifications in a cost-effective manner. The processing Mapping Partner shall ensure that all Flood Profiles for restudied streams reflect 1- percent-annual-chance (100-year) flood elevations and reflect the streambed or hydraulic baseline. The processing Mapping Partner shall ensure that all structures reflected on the effective Flood Profiles as well as any new structures are depicted on the revised Flood Profile. All cross sections shown on the revised FIRM (or FBFM) and in the Floodway Data Table must be clearly reflected on the submitted profiles. The processing Mapping Partner shall obtain approval from the FEMA Lead for deviations from the effective Flood Profile format. The processing Mapping Partner shall adjust the backwater area on Flood Profiles for tributaries that flow into a revised stream to reflect the revised elevations. [February 2002] Reach and Zone Labels In situations where the FIRM is being produced, in whole or in part, in the Map Initiatives Format, the processing Mapping Partner shall remove reach and zone labels from all Flood Profiles. [February 2002] J.2.3.2 Flood Profile Production Flood Profiles may be prepared digitally or manually; digital files are preferred. Additional guidance regarding digital and manual Flood Profile production is provided in the subsections that follow. [February 2002] Digital Flood Profile Production Two software applications for profile creation are available for download, free of charge, from the FEMA website (http://www.fema.gov/mit/tsdfrm_soft.htm). The first application is RASPLOT. Refer to the RASPLOT User's Manual, available for separate download, for guidance regarding its use. The second application is FISPLOT. The FISPLOT program allows users to create drawing interchange format (*.DXF) files from HEC-2 input and output files. FISPLOT may later be enhanced so that it can generate Flood Profiles from other backwater computer models, such as WSPRO and WSP2. The FISPLOT-generated *.DXF files can then be imported into AutoCAD(r) and all the appropriate FEMA symbols, such as bridge deck information, are displayed in an AutoCAD(r) drawing (*.DWG) file. However, equivalent software may be used, provided that the output file produces a Flood Profile that meets the requirements above. Mapping partners should contact the RPO to discuss using alternative software platforms. [February 2002] Manual Flood Profile Production Flood Profiles are to be neatly drawn and lettered on standard 11"x17", 10x10 to the inch grid, mylar profile sheets. At the submitting Mapping Partner's request, the FEMA Lead may provide assistance in obtaining blank standard mylar profile sheets. Use of non-standard profile sheets (i.e., continuous computer-generated profile sheets or paper copy vs. mylar) shall be coordinated and approved by the FEMA Lead. If the use of a continuous profile sheet is approved, the Mapping Partner shall ensure that the selected vertical scale would not necessitate replotting the profiles; i.e., the Mapping Partner responsible for producing the final Flood Profile should be able to trace-draft the submitted continuous profile sheet onto standard 11"x17" mylar profile sheets. [February 2002] J.3 Volume Printing The processing Mapping Partner shall ensure that the following requirements are met when appropriate: * FIS reports exceeding 150 pages in length shall be subdivided into two or more volumes. * No more than 100 pages shall be included in any volume of a multiple-volume FIS report. * Where possible, reports shall be subdivided so that volumes begin and end at logical breakpoints; however, the number of volumes must be minimized. * One listing, Tables of Contents, shall be prepared for all volumes. * A copy of the complete Tables of Contents shall appear in each volume of the FIS report. [February 2002] J.4 Future-Conditions Flood Hazard Information At the request of a community and with the approval of FEMA, FIS reports may include, for informational purposes, flood hazard information based on projected- or future-conditions hydrologic and hydraulic analyses. If community officials request that FEMA show the future- conditions flood hazard information in the FIS report, the future-conditions flood insurance risk zone shall be referenced in the FIS report. Although graphic specifications are flexible for the presentation of future-conditions flood hazard information, the zone label for the future- conditions flood insurance risk zone will be "Zone X (Future Base Flood)." The future-conditions flood insurance risk zone shall be defined in the FIS report as follows: Zone X (Future Base Flood) is the flood insurance risk zone that corresponds to the 1-percent-annual-chance floodplains that are determined based on future- conditions hydrology. No BFEs or base flood depths are shown within this zone. FEMA opted to use the Zone X (Future Base Flood) designation for the future-conditions flood hazard areas, in lieu of a new flood insurance risk zone designation, to minimize confusion by users of the FIRM that make determinations regarding Federal mandatory flood insurance purchase requirements. Those users now recognize that areas designated as Zone X (shaded) are floodprone, but that the mandatory flood insurance purchase requirement does not apply. Because the risk premium rates for buildings located in the future-conditions 1-percent-annual- chance (100-year) floodplain will be the rate comparable to other areas outside the SFHA, FEMA believes designating these areas as "Zone X (Future Base Flood)" will be sufficient distinction. [February 2002] J.5 Sample Flood Insurance Study Report The following sample single-jurisdiction FIS report, for a fictional Massachusetts community, is in the final form to be submitted to the MSC for printing by GPO. The sample FIS report is for a community subject to both riverine flooding and coastal flooding (i.e., wave height and runup hazards). This FIS report has been prepared in the Map Initiatives format with an extra section added as an addendum at the end of the report. The following sample FIS report is intended only as a graphic example of a report format; the content is not intended to be an authoritative example of an actual FIS report. The sections, subsections, paragraphs, and language required for every FIS report are presented in bold-faced type. The submitting Mapping Partner and processing Mapping Partner may use the language of the specific content within the sections and subsections for guidance. [February 2002] TOWN OF FLOODPORT, MASSACHUSETTS FLOOD COUNTY REVISED: August 31, 2001 Federal Emergency Management Agency COMMUNITY NUMBER - 259999 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. This FIS report was revised on August 31, 2001. Users should refer to Section 10.0, Revisions Description, for further information. Section 10.0 is intended to present the most up-to-date information for specific portions of this FIS report. Therefore, users of this report should be aware that the information presented in Section 10.0 supersedes information in Sections 1.0 through 9.0 of this FIS report. Effective Date: January 15, 1992 Revised Dates: November 11, 1992 (Flood Insurance Rate Map only) December 3, 1996 August 31, 2001 TABLE OF CONTENTS .Page INTRODUCTION 1 1.1 Purpose of Study 1 1.2 Authority and Acknowledgments 1 1.3 Coordination 1 2.0 AREA STUDIED 2 2.1 Scope of Study 2 2.2 Community Description 2 2.3 Principal Flood Problems 5 2.4 Flood Protection Measures 5 3.0 ENGINEERING METHODS 6 3.1 Hydrologic Analyses 6 3.2 Hydraulic Analyses 10 4.0 FLOODPLAIN MANAGEMENT APPLICATIONS 16 4.1 Floodplain Boundaries 16 4.2 Floodways 17 5.0 INSURANCE APPLICATION 19 6.0 FLOOD INSURANCE RATE MAP 20 7.0 OTHER STUDIES 21 8.0 LOCATION OF DATA 21 9.0 BIBLIOGRAPHY AND REFERENCES 21 10.0 REVISIONS DESCRIPTION 22 10.1 First Revision (Revised December 3, 1996) 22 a. Acknowledgments 22 b. Scope 22 c. Other Studies 22 d. References and Bibliography 22 10.2 Second Revision (Revised August 31, 2001) 22 a. Acknowledgments 22 b. Coordination 22 c. Scope 22 d. Hydrologic and Hydraulic Analyses 22 e. Floodways 22 f. Other Studies 22 g. References and Bibliography 22 FIGURES Figure 1 - Transect Location Map 3 Figure 2 - Floodway Schematic 19 TABLES Table 1 - Summary of Discharges 7 Table 2 - Summary of Stillwater Elevations 9 Table 3 - Transect Descriptions 14 Table 4 - Transect Data 15 Table 5 - Floodway Data 21 Table 6 - Revised Summary of Discharges 28 EXHIBITS Exhibit 1 - Flood Profiles Rocky River Panel 01P Exhibit 2 - Flood Insurance Rate Map Index Flood Insurance Rate Map FLOOD INSURANCE STUDY TOWN OF FLOODPORT, FLOOD COUNTY, MASSACHUSETTS 1.0 INTRODUCTION 1.1 Purpose of Study This Flood Insurance Study investigates the existence and severity of flood hazards in the Town of Floodport, Flood County, Massachusetts, 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. 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. 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. The hydrologic and hydraulic analyses for this study were performed by John Brown Engineering Corporation, for the Federal Emergency Management Agency (FEMA), under Contract No. H-1983. This work was completed in December 1985. 1.3 Coordination The initial Consultation Coordination Officer (CCO) meeting was held on April 12, 1983, and attended by representatives of FEMA, the Town of Floodport, and the study contractor. Coordination with Town officials and Federal, State, and regional agencies produced information pertaining to floodplain regulations, community maps, flood history, and other hydrologic data. The U.S. Army Corps of Engineers (USACE) and the National Oceanic and Atmospheric Administration (NOAA) were contacted for data on tide elevations. Coordination with these agencies concerning coastal flood elevations was continued during the study. The Massachusetts Department of Public Works (MDPW) was contacted for information on historic flooding and high-water marks. Vertical control data used to establish the network of elevation reference marks were provided by the MDPW, NOAA, U.S. Geological Survey (USGS), and U.S. Coast and Geodetic Survey. An intermediate CCO meeting was held on February 14, 1984, and attended by representatives of FEMA, the community, and the study contractor. The purpose of this meeting was to present preliminary results of the study to the community. The results of the study were reviewed at the final CCO meeting held on December 1, 1986, and attended by representatives of FEMA, the community, and the study contractor. All problems raised at that meeting have been addressed. 2.0 AREA STUDIED 2.1 Scope of Study This FIS covers the incorporated areas of the Town of Floodport, Flood County, Massachusetts. Riverine flooding on the Rocky River from approximately 100 feet downstream of U.S. Route 1 to the upstream corporate limits was studied by detailed methods. Tidal flooding from the Atlantic Ocean, including wave action, and the Merrimack River was also studied by detailed methods. The areas studied by detailed methods were selected with priority given to all known flood hazard areas and areas of projected development or proposed construction through December 1990. Keiths and Richards Creeks were studied by approximate methods for their lengths within the Town of Floodport. Approximate analyses were used to study those areas having low development potential or minimal flood hazards. The scope and methods of study were proposed to, and agreed upon, by FEMA and the Town of Floodport. 2.2 Community Description The Town of Floodport is located in northeastern Flood County, in northeastern Massachusetts, approximately 35 miles north of the City of Boston. It is bordered by the Atlantic Ocean to the east; the Town of Rowley to the south; the Towns of West Newbury, Groveland, and Georgetown to the west; and the City of Newburyport to the north. Because of its proximity to the Atlantic Ocean, Floodport attracts both a permanent and transient population. According to the 1980 State census, the town had an estimated population of 4,239. The population density in 1980 was 167 persons per square mile (Massachusetts Department of Commerce, 1980). Floodport is experiencing growth pressure, and coastal seasonal homes are being converted to year-round residences. It is estimated that the population of the town will increase approximately 51 percent by 1990 (New England River Basins Commission, 1975). The total area contained within the corporate limits of Floodport is 25.4 square miles. Of the total area, only 8.4 percent is classified as urban land. The remaining land uses are as follows: forest, 34.6 percent; wetlands, 38.2 percent; agriculture and open land, 16.8 percent; mining and waste disposal, 0.3 percent; and recreation, 1.7 percent (Massachusetts Agricultural Experiment Station, 1974). Development along the Floodport coast is primarily residential (permanent and seasonal) and recreational. The coast is characterized by the sand dunes of the barrier beach, Plum Island, which extends from the confluence of Plum Island Sound and the Ipswich River north to the Merrimack River. Residential development is located on the northern portion of Plum Island. The remainder of Plum Island, except Camp Sea Haven, is part of the Parker River National Wildlife Refuge. To the west of Plum Island is an extensive system of salt marshes associated with the Mill and Plum Island Rivers. The Plum Island River, a tidal creek, is a waterway for small boats between the Merrimack River and Plum Island Sound. Residential development is located west of the salt marshes, approximately 2 miles from the coast. Residential development is also located in the southwestern corner of town. The coast is relatively flat, ranging from sea level to an approximate elevation of 30 feet. Inland, the topography is level, with an average elevation of 50 feet. Small hills, with elevations of 100 to 150 feet, are located in the southern and southwestern portions of town. The soils are predominantly wet throughout eastern and central Floodport. Northwestern Floodport has rough and stony soils. Floodport has a tidal shoreline of 48.3 miles (Massachusetts Department of Commerce, 1975). The Rocky River and its tributaries drain most of the town. The river, which is 21 miles long and has a drainage area of approximately 35 square miles, has its headwaters in West Boxford and flows northeasterly until it joins Plum Island Sound in Floodport. The climate of Floodport is variable. The average annual precipitation is approximately 43 inches; the average annual snowfall is approximately 47 inches. The Floodport area experiences no dry season. From June to September, rainfall usually occurs as showers or thunderstorms. The thunderstorms produce heavy, sometimes excessive, amounts of rain. Throughout the year, the heaviest gales usually come from the northeast and east and are more common and severe during the winter. "Northeasters," as they are called, produce an abundance of rain and snow. The average annual temperature is approximately 51 °F; the mean temperatures for January and July are 28°F and 74.8°F, respectively (NOAA, 1976). 2.3 Principal Flood Problems The low-lying coastal areas of the town adjacent to the Atlantic Ocean are subject to the periodic flooding and wave attack that accompanies storms such as northeasters. Hurricanes have not produced significant flooding in these areas. The majority of coastal storms cause damage only to low coastal roads, boats, beaches, and seawalls. Occasionally, a major storm accompanied by strong onshore winds and high tides results in surge and wave activity that causes extensive property damage and erosion. Four of the more significant storms in the Floodport area were those of December 1901 and 1959 (approximately 160- and 15-year recurrence intervals, respectively) and February 1972 and 1978 (approximately 10- and 70-year recurrence intervals, respectively). These storms damaged harbors, marinas, and residential and commercial developments in the floodprone coastal areas. In addition to flooding, serious shorefront erosion has occurred at Plum Island since the early 1880s, when the mouth of the Merrimack River was located approximately 0.5 mile south of its present position. Jetties, which were constructed at the turn of the century, had stabilized the entrance of the river at its present location and tended to create a buildup of the oceanfront shores on the northern end of the island. However, since 1938, continuous recession of the shoreline has occurred, resulting primarily from severe storm surge and coincident wave action. During the severe storm that occurred on February 19, 1972, a wide fronting beach and backlying dunes were destroyed, and several cottages were damaged or destroyed. This storm made the island susceptible to further damage. Riverine flooding has not generally been as severe as coastal flooding in the Floodport area. Extreme water levels on the Rocky River are primarily caused by runoff from heavy rainfall and snowmelt. 2.4 Flood Protection Measures Present and future demands associated with the seasonal tourist industry will further intensify the pressure for development of floodprone coastal lands. However, the adoption of State and local development regulations concerning floodplain management will help alleviate storm-related losses (USACE, 1971). No major structural flood protection measures exist or are planned for the Town of Floodport. 3.0 ENGINEERING METHODS For the flooding sources studied by detailed methods 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 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 (100-year) 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. 3.1 Hydrologic Analyses Hydrologic analyses were carried out to establish peak discharge-frequency relationships for each flooding source studied by detailed methods affecting the community. Floodflow frequencies for the Rocky River were based on a statistical analysis of USGS gage data. These data were analyzed in accordance with criteria outlined in Bulletin 17B (Interagency Advisory Committee on Water Data, 1982). Discharge- frequency data were based on a USGS computer model (USGS, 1976). The model was run on November 20, 1983, using a systematic record of 32 years and a generalized skew coefficient; the input for, and assumptions of, the analysis were reviewed and accepted for use in this study. Peak discharge-drainage area relationships for the Rocky River are shown in Table 1. Table 1. Summary of Discharges Flooding Source and Location Drainage Area (square miles) Peak Discharges (cubic feet per second) 10-Percent- Annual-Chance 2-Percent- Annual-Chance 1-Percent- Annual-Chance 0.2-Percent- Annual-Chance Rocky River At U.S. Route 1 13.6 415 685 831 1,261 In New England, the flooding of low-lying coastal areas is caused primarily by storm surge generated by extratropical coastal storms called northeasters. Hurricanes also occasionally produce significant storm surge in New England, but they do not occur nearly as frequently as northeasters. To calculate the storm surge and total storm tide elevations produced by historic storms, storm pressures and windfields were determined. A computer model was developed to simulate these fields based on several easily obtained storm parameters of northeasters. A detailed description of this model is presented in the report entitled "Development and Verification of a Synthetic Northeaster Model for Coastal Flood Analysis" (Stone and Webster Engineering Corporation, 1978). A different model was used to simulate the windfields and pressures of the hurricanes considered in this analysis (Stone and Webster Engineering Corporation, 1977). When coupled with a computer surge model, the storm tide along the shoreline could be calculated for each storm of interest. NOAA synoptic weather charts were searched to determine the northeasters and hurricanes that could potentially produce significant flooding in the Floodport area (NOAA, 1978). Tidal records from tide gages in the New England area were examined to verify which historic storms produced high-water elevations. For the analysis of flood levels, 165 storms that occurred between 1942 and 1978 were considered. The flood levels associated with historic storms were simulated using a modified version of the FEMA storm surge model (Tetra Tech, Inc., 1977, and Stone and Webster Engineering Corporation, 1978). Input to the model consisted of windfields and pressures generated either by the synthetic northeaster model or a hurricane-windfield-and-pressure-field model for each historic storm selected. The study area was modeled using a square grid of sufficient resolution to accurately represent the offshore bathymetry and shoreline configuration. The grid mesh covered an area from Cape Cod Bay to north of Portsmouth, New Hampshire, including Boston Harbor. Output from the model included the time history of storm-induced stillwater elevations for the communities in the study areas. The total stillwater elevation was calibrated using historic tide elevation data at Boston, Massachusetts, and Portsmouth, New Hampshire. Thus, the historic storm-induced flood levels in Floodport could be simulated for each storm considered in the analysis. The extent and frequency of coastal flooding were determined by conducting a frequency analysis of annual minimum tidal heights along the Atlantic coast at Floodport. Some historic storm-tide heights, consisting of both an astronomical tide and a storm-surge contribution, were determined by the mathematical simulation of historic northeasters and hurricanes described above; others, for which associated storm data were not available, were obtained by a correlation analysis using tide data from Boston or Portsmouth. The database at the Boston gage extended discontinuously from 1848 to 1978; the shorter record at Portsmouth was lengthened by a statistical correlation with data at Boston and Portland, Maine. The annual maximums of these reproduced historic water elevations were fitted with a log-Pearson Type III distribution. Elevations for floods of the selected recurrence intervals for the Atlantic Ocean and the Merrimack River are shown in Table 2. Table 2. Summary of Stillwater Elevations Elevation (Feet) Flooding Source and Location 10-Percent- Annual-Chance 2-Percent- Annual-Chance 1-Percent- Annual-Chance 0.2-Percent- Annual-Chance Atlantic Ocean Entire Shoreline Within Floodport 8.2 8.9 9.2 9.8 Rocky River Entire Shoreline Within Floodport 5.9 7.2 8.2 8.9 The analyses reported in this FIS report reflect the stillwater elevations due to tidal and wind setup effects. The effects of wave action were also considered in the determination of flood hazard areas. A detailed description of the methodology employed in this analysis can be found in the report entitled "Determination of Coastal Storm Tide Levels" (Stone and Webster Engineering Corporation, 1978). Coastal structures that are located above stillwater flood elevations can still be severely damaged by wave runup, wave-induced erosion, and wave-borne debris. For example, during a northeaster in February 1978, considerable damage along the Massachusetts coast was caused by wave activity, even though most of the damaged structures were above the high-water level (USACE, 1979). The extent of wave runup past stillwater levels depends greatly on the wave conditions and local topography. Wave heights and corresponding wave crest elevations were determined using the methodology developed by the National Academy of Sciences (NAS) (NAS, 1977). The wave runup was determined using the methodology developed for FEMA by Stone and Webster Engineering (Stone and Webster Engineering Corporation, 1981). 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 us 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 topographic maps compiled from aerial photographs (James W. Sewall Company, 1977). Below- water sections were obtained by field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry. 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 (Exhibit 2). Water-surface elevations for floods of the selected recurrence intervals were computed through use of the USACE HEC-2 step-backwater computer program (USACE, 1984). Starting water-surface elevations for the Rocky River were determined using critical depth. 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. The channel "n" values for the Rocky River ranged from 0.015 to 0.050, and the overbank "n" values ranged from 0.015 to 0.050. 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. Hydraulic analyses, considering storm characteristics, the shoreline, and bathymetric characteristics of the tidal flooding source studied, were carried out to provide estimates of the elevations of floods of the selected recurrence intervals along the shoreline. Areas of coastline subject to significant wave attack are referred to as coastal high hazard zones USACE has established the 3-foot breaking wave as the criterion for identifying the limit of coastal high hazard zones (USACE, 1975). The 3-foot wave has been determined as the minimum size wave capable of causing major damage to conventional wood-frame or brick-veneer structures. A wave height analysis was performed to determine wave heights and corresponding wave crest elevations for the areas inundated by tidal flooding. A wave runup analysis was performed to determine the height and extent of runup beyond the limit of tidal inundation. The results of these analyses were combined into a wave envelope, which was constructed by extending the maximum wave runup elevation seaward to its intersection with the wave crest profile. The methodology for analyzing wave heights and corresponding wave crest elevations was developed by the NAS (NAS, 1977). The NAS methodology is based on three major concepts. First, a storm surge on the open coast is accompanied by waves. The maximum height of these waves is related to the depth of water by the following equation: Hb = 0.78d where Hb is the crest-to-trough height of the maximum or breaking wave and d is the stillwater depth. The elevation of the crest of an unimpeded wave is determined using the equation: Zw = S* + 0.7H* = S* + 0.55d where Zw is the wave crest elevation, S* is the stillwater elevation at the site, and H* is the wave height at the site. The 0.7 coefficient is the portion of the wave height that reaches above the stillwater elevation. Hb is the upper limit for H*. The second major concept is that the breaking wave height may be diminished by dissipation of energy by natural or manmade obstructions. The wave height transmitted past a given obstruction is determined by the following equation: Ht = Phi where Ht is the transmitted wave height, B is a transmission coefficient ranging from 0.0 to 1.0, and Hi is the incident wave height. The coefficient is a function of the physical characteristics of the obstruction. Equations have been developed by the NAS to determine the transmission coefficient for vegetation, buildings, natural barriers such as dunes, and manmade barriers such as breakwaters and seawalls (NAS, 1977). The third major concept concerns unimpeded reaches between obstructions. New wave generation can result from wind action. This added energy is related to distance and mean depth over the unimpeded reach. The methodology for analyzing wave runup was developed by Stone and Webster Engineering Corporation (Stone and Webster Engineering Corporation, 1981). The wave runup computer program operates using an ensemble of deepwater wave heights, Hi; the stillwater elevation, S*; a wave period, Ts; and the beach slope, m. For Floodport, wave heights range from 2 feet to 6 feet; the wave period is 4 seconds. These concepts and equations were used to compute wave envelope elevations associated with the 1-percent-annual-chance storm surge. Accurate topographic, land-use, and land-cover data are required for the coastal analyses. Maps of the study area, prepared at a scale of 1:2,400 with a contour interval of 5 feet, were used for the topographic data (James W. Sewall Company, 1977). The land-use and land-cover data were obtained by field surveys. Wave height and wave runup were computed along transects that were located perpendicular to the average mean shoreline. The transects were located with consideration given to the physical and cultural characteristics of the land so that they would closely represent conditions in their locality. Transects were located close together in areas of complex topography and dense development. In areas having more uniform characteristics, the transects were spaced at larger intervals. It was also necessary to locate transects in areas where unique flooding existed and in areas where computed wave heights varied significantly between adjacent transects. Figure 2 illustrates the location of the transects for the community. A listing of the transect locations and stillwater elevations, as well as the maximum wave crest (or wave runup) elevations, is provided in Table 3. Along each transect, wave envelope elevations were computed considering the combined effects of changes in ground elevation, vegetation, and physical features. Between transects, elevations were interpolated using the previously cited topographic maps, land-use data, land-cover data, and engineering judgment to determine the areal extent of flooding. The results of the calculations are accurate until local topography, vegetation, or cultural development within the community undergoes any major changes. The results of this analysis are summarized in Table 4. Historic flood damage information was also used in the determination of floodprone areas along the Floodport shoreline (USGS, 1979). Table 3. Transect Descriptions 1-Percent-Annual-Chance Flood Elevation (Feet) Transect Location Stillwater Maximum Wave1 1 From Plum Island Point south to Plum Island Turnpike, extended east 9.2 - 8.2 142 2 From Plum Island Turnpike, extended east, to Perry Road, extended east 9.2 183 3 From Perry Road, extended east, to Mason Street, extended east 9.3 142 4 From Mason Street, extended east, to 8th Street, extended east 9.3 142 5 From 8th Street extended east, to approximately 3,000 feet south of 1st Street 9.3 173 1Due to map scale limitations, the maximum wave elevation is not shown on the Flood Insurance Rate Map 2Maximum wave height elevation 3Maximum wave runup elevation Table 4. Transect Data Flooding Source Stillwater Flood Elevation (Feet) Base Flood Elevation (Feet)1 10-Percent- Annual-Chance 2-Percent- Annual-Chance 1-Percent- Annual-Chance 0.2-Percent- Annual-Chance Atlantic Ocean and Merrimack River Transect 1 8.2 5.9 8.9 7.2 9.2 8.2 9.8 8.9 9.14 8-11 Atlantic Ocean Transect 2 Transect 3 Transect 4 Transect 5 8.2 8.3 8.3 8.3 8.9 9.0 9.0 9.0 9.2 9.3 9.3 9.3 9.8 10.0 10.0 10.0 9.18 9-14 9-14 9-17 1Due to map scale limitations, BFEs shown on the Flood Insurance Rate Map represent average elevations for the depicted Zones 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. 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. 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 (100-year) flood elevations and delineations of the 1- and 0.2-percent-annual-chance (500-year) 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, Floodway Data Table and Summary of Stillwater Elevations 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 (100-year) flood has been adopted by FEMA as the base flood for floodplain management purposes. The 0.2-percent-annual- chance (500-year) 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 sections, the boundaries were interpolated using topographic maps at a scale of 1:2,400, with a contour interval of 5 feet (James W. Sewall Company, 1977). For tidal areas without wave action, the 1- and 0.2-percent-annual-chance floodplain boundaries were delineated using topographic maps at a scale of 1:2,400, with a contour interval of 5 feet (James W. Sewall Company, 1977). For the tidal areas with wave action, the floodplain boundaries were delineated using the elevations determined at each transect; between transects, the boundaries were interpolated using engineering judgment; land-cover data; and topographic maps at a scale of 1:2,400, with a contour interval of 5 feet (James W. Sewall Company, 1977). The 1-percent-annual-chance floodplain was divided into whole-foot elevation zones based on the average wave envelope elevation in that zone. Where the map scale did not permit these zones to be delineated at l-foot intervals, larger increments were used. 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 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 sections, the floodway boundaries were interpolated. The results of the floodway computations have been tabulated for selected cross sections (Table 6). 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. Portions of the floodway for the Rocky River extend beyond the corporate limits. 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 1.0 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in Figure 2. FLOODING SOURCE FLOODWAY 1-PERCENT-ANNUAL-CHANCE FLOOD WATER-SURFACE ELEVATION (FEET NAVD) CROSS SECTION DISTANCE1 WIDTH (FEET) SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE ROCKY RIVER A 11430 100 433 4.3 6.3 4.02 4.3 0.3 B 11900 160 915 2.0 6.3 4.62 5.3 0.7 C 12200 300 1190 1.6 6.3 5.62 5.6 0.0 D 13100 300 1327 1.4 6.3 6.12 6.1 0.0 E 14900 250 1280 1.3 7.3 7.3 7.6 0.3 F G H I J K 1Feet above mouth 2Elevation computed without consideration of backwater effects from Cobb River (What about cross sections F through K?) TAB LE 6 FEDERAL EMERGENCY MANAGEMENT AGENCY TOWN OF FLOODPORT, MA (FLOOD COUNTY) FLOODWAY DATA ROCKY RIVER Figure 2. Floodway Schematic 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 AH Zone AH is the flood insurance risk zone that corresponds to the areas of 1-percent- annual-chance shallow flooding (usually areas of ponding) where average depths are between 1 and 3 feet. Whole-foot BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Zone AO Zone AO is the flood insurance risk zone that corresponds to the areas of 1-percent- annual-chance shallow flooding (usually sheet flow on sloping terrain) where average depths are between 1 and 3 feet. Average whole-foot base flood depths derived from the detailed hydraulic analyses are shown within this zone. Zone AR Zone AR is the flood insurance risk zone that corresponds to an area of special flood hazard formerly protected from the 1-percent-annual-chance flood event 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- percent-annual-chance or greater flood event. Zone A99 Zone A99 is the flood insurance risk zone that corresponds to areas of the 1-percent- annual-chance floodplain that will be protected by a Federal flood protection system where construction has reached specified statutory milestones. No BFEs or depths are shown within this zone. Zone V Zone V is the flood insurance risk zone that corresponds to the 1-percent-annual- chance coastal floodplains that have additional hazards associated with storm waves. Because approximate hydraulic analyses are performed for such areas, no BFEs are shown within this zone. Zone VE Zone VE is the flood insurance risk zone that corresponds to the 1-percent-annual- chance coastal floodplains that have additional hazards associated with storm waves. 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, 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. Zone X (Future Base Flood) Zone X (Future Base Flood) is the flood insurance risk zone that corresponds to the 1-percent-annual-chance floodplains that are determined based on future-conditions hydrology. No BFEs or base flood depths are shown within this zone. Zone D Zone D is the flood insurance risk zone that corresponds to unstudied areas where flood hazards are undetermined, but possible. 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. 7.0 OTHER STUDIES Using National Ocean Survey tide gage data (NOAA, 1984), the USACE has predicted 10-, 2-, 1-, and 0.2-percent-annual-chance flood levels at Boston, Massachusetts, and Portsmouth, New Hampshire . The USACE results compare favorably with flood levels determined in this study, considering the distance between Ipswich and the National Ocean Survey gaging stations. FEMA has published FIS reports and FIRMs for the Towns of West Newbury (FEMA, 1979) and Georgetown (FEMA, 1978). The results presented in the FIS report and on the FIRM for the Town of Floodville are in exact agreement with the results for those towns. An FIS for the Town of West Newburyport is in progress (FEMA, unpublished). The results of that study will be in exact agreement with the results of this study. 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, J. W. McCormack Post Office and Courthouse Building, Room 462, Boston, Massachusetts 02109. 9.0 BIBLIOGRAPHY AND REFERENCES Commonwealth of Massachusetts, Department of Commerce, Profile of Floodport, Boston, Massachusetts, 1975. Commonwealth of Massachusetts, Department of Commerce, Division of Census, Population-Area-Density, Boston, Massachusetts, 1980. Federal Emergency Management Agency Flood Insurance Study, Town of West Newbury, Massachusetts, December 15, 1979. Federal Emergency Management Agency, Flood Insurance Study, Town of Georgetown, Massachusetts, December 4, 1978. Federal Emergency Management Agency, Flood Insurance Study, Town of Newburyport, Massachusetts, unpublished.. James W. Sewall Company, Topographic Maps, Scale 1:2,400, Contour Interval 5 Feet. Floodport, Massachusetts (1977). Massachusetts Agricultural Experiment Station, Remote Sensing: 20 Years of Change in Essex County, Massachusetts, 1951-1971. William P. MacConnel, August 1974. . National Academy of Sciences, Methodology for Calculating Wave Action Effects Associated with Storm Surges, 1977. New England River Basins Commission, Report of the Southeastern New England Study. Boston, Massachusetts, December 1975. Stone and Webster Engineering Corporation, Determination of Coastal Storm Tide Levels., Boston, Massachusetts, October 1978. Stone and Webster Engineering Corporation, Manual for Wave Runup Analysis, Coastal Flood Insurance Studies, Boston, Massachusetts, November 1981. Stone and Webster Engineering Corporation, Development and Verification of a Synthetic Northeaster Model for Coastal Flood Analysis, Boston, Massachusetts, October 1978. Stone and Webster Engineering Corporation,. SWECO 7501-NP-A, Two-Dimensional Coastal Storm Surge Model. Boston, Massachusetts, July 1977. Tetra Tech, Inc., for the Federal Emergency Management Agency, Coastal Flooding Handbook, Pasadena, California, May 1977. U.S. Department of the Army, Corps of Engineers, Hydrologic Engineering Center, HEC- 2 Water Surface Profiles, Generalized Computer Program. Davis, California, April 1984. U.S. Department of the Army, Corps of Engineers, New England Division, "A Report on the Assessment of Flood Damage Resulting from the Storm of February 6-7, 1978, Along the Coastline from Orleans, Massachusetts, to New Castle, New Hampshire," Waltham, Massachusetts, February 1979. U.S. Department of the Army, Corps of Engineers, Galveston District, Guidelines for Identifying Coastal High Hazard Zones, Galveston, Texas, June 1975. U.S. Department of the Army, Corps of Engineers, New England Division, National Shoreline Study, Regional Inventory Report, North Atlantic Region, Volume 1, Waltham, Massachusetts, 1971. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Ocean Survey, Tide Table, 1931-1984, East Coast of North and South America, 1984. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Weather Service, Environment Data Service, Synoptic Weather Charts, 1978, 1976, 1972, 1970, 1969, 1968, 1967, 1966, 1962, 1961, 1960, 1959, 1958, 1957, 1954, 1953, 1950, 1944, 1940, 1931. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, United States Coast Pilot 1, Atlantic Coast, Eastport to Cape Cod, November 1976. U.S. Department of Housing and Urban Development, Federal Insurance Administration, Flood Hazard Boundary Map, Town of Floodport, Massachusetts, Scale 1:6,000, April 4, 1978. U.S. Department of the Interior, Geological Survey, Computer Program E-431, Users Manual, Computer Applications for Step-Backwater and Floodway Analyses, James O. Shearman, 1976. Interagency Advisory Committee on Water Data, Office of Water Data Coordination, Hydrology Subcommittee, Bulletin No. 17B, Guidelines for Determining Flood Flow Frequency. September 1981, revised March 1982. U.S. Department of the Interior, Geological Survey, Water Resources Investigations 78- 61, Coastal Flood of February 7, 1978, in Maine, Massachusetts, and New Hampshire, 1979. 10.0 REVISIONS DESCRIPTION This section has been added to provide information regarding significant revisions made since the original FIS report and FIRM were printed. Future revisions may be made that do not result in the republishing of the FIS report. All users are advised to contact the Community Map Repository at the address below to obtain the most up-to-date flood hazard data. Town of Floodport Engineering Department 101 Main Street, Suite 999 Floodport, MA 10.1 First Revision (Revised December 3, 1996) a. Acknowledgments The WHAFIS analyses for this revision was performed by Tackney & Associates, Inc. FEMA reviewed and accepted these data for purposes of this revision. b. Scope Based on better topographic and vegetation in formation, the wave height elevations for the three additional transects along the Atlantic Ocean, south of transect 22, were computed using the WHAFIS computer model (FEMA, 1981). The additional transects are shown on Figure 2, Transect Location Map, as transects 22A, 22B, and 22C, and are described in Table 2, Summary of Stillwater Elevations. Additionally, the zone designations and BFEs were changed as a result of a revised WHAFIS analysis and to agree with the FIRM for Seaside County (FEMA, 1986). c. Other Studies This revision is in agreement with the published FIS for Seaside County, Massachusetts (FEMA, 1986). This revision does not reflect information from any other contiguous community. d. References and Bibliography Federal Emergency Management Agency, Flood Insurance Study, Town of Georgetown, Massachusetts, June 1986 Federal Emergency Management Agency, Users Manual for Wave Height Analysis, Revised February 1981. 10.2 Second Revision (Revised August 31, 2001) a. Acknowledgments The hydrologic and hydraulic analyses for this revision were taken from a report titled "Floodplain Management Study, Shaw County, Massachusetts," prepared by the U.S. Soil Conservation Service (SCS) (SCS, 1984). FEMA reviewed and accepted these data for purposes of this revision. b. Coordination A final CCO meeting was held on September 4, 1999, to review the results of this revision. c. Scope This revision includes a revised detailed analysis of the Rocky River from its confluence with Big Creek to U.S. Route 1. d. Hydrologic and Hydraulic Analyses Revised flood discharges along the Rocky River were established by valley flood routings computed using the SCS TR-20 computer program (USCS, 1982). Peak drainage-discharge area relationships for the 10-, 2-, 1-, and 0.2-percent-annual-chance floods are shown in Table 7. Table 7. Revised Summary of Discharges Flooding Source and Location Drainage Area (square miles) Peak Discharges (cubic feet per second) 10-Percent- Annual-Chance 2-Percent- Annual-Chance 1-Percent- Annual-Chance 0.2-Percent- Annual-Chance Rocky River At U.S. Route 1 13.6 420 690 850 1,298 e. Other Studies The FIS for the Town of Watertown (FEMA, unpublished), in progress as of the date of this Revisions Description, agrees with this study. f. Bibliography and References Federal Emergency Management Agency, Flood Insurance Study, Town of Watertown, Massachusetts, unpublished. U.S. Department of Agriculture, Soil Conservation Service, Floodplain Management Study. Shaw County, Massachusetts, 1984. U.S. Department of Agriculture, Soil Conservation Service, Technical Release No. 20, Computer Program for Project Formulation, Hydrology, May 1982. Figure J-1. Cover for Multiple-Volume Countywide Report Figure J-2. Cover for Multiple-Volume Non-Countywide Report Figure J-3. Cover for Multiple-Volume Single-Jurisdiction Report Figure J-4. Table of Contents for Multiple-Volume Countywide Report TABLES OF CONTENTS Table of Contents - Volume 1 - April 22, 1999 Page 1.0 INTRODUCTION 1 1.1 Purpose of Study 1 1.2 Authority and Acknowledgments 2 1.3 Coordination 7 2.0 AREA STUDIED 8 2.1 Scope of Study 8 2.2 Community Description 18 2.3 Principal Flood Problems 19 2.4 Flood Protection Measures 21 3.0 ENGINEERING METHODS 23 3.1 Hydrologic Analyses 23 3.2 Hydraulic Analyses 40 4.0 FLOODPLAIN MANAGEMENT APPLICATIONS 48 4.1 Floodplain Boundaries 48 4.2 Floodways 49 5.0 INSURANCE APPLICATIONS 123 6.0 FLOOD INSURANCE RATE MAP 125 7.0 OTHER STUDIES 125 8.0 LOCATION OF DATA 130 9.0 BIBLIOGRAPHY AND REFERENCES 130 Table of Contents - Volume 1 - continued Page FIGURES Figure 1 - Floodway Schematic 123 TABLES Table 1 - Streams Studied by Detailed Methods 8, 10 Table 2 - Scope of Revision for August 2, 1995, Countywide FIS 12-14 Table 3 - Letters of Map Revision 15-17 Table 4 - Summary of Discharges 28-40 Table 5 - Summary of Roughness Coefficients 45-47 Table 6 - Floodway Data 51-122 Table 7 - Community Map History 126-128 EXHIBITS Exhibit 1 - Flood Profiles Alum Creek Panels 01P-04P Barbee Ditch Panels 05P-07P Barnes Ditch Panels 08P-10P Beem Ditch Panels 11P-12P Big Darby Creek Panels 13P-17P Big Run Panels 18P-20P Big Walnut Creek Panels 21P-28P Billingsley Ditch Panels 29P-31P Bishop Run Panels 32P-33P Table of Contents - Volume 2 - April 19, 1997 EXHIBITS - continued Exhibit 1 - Flood Profiles - continued Blacklick Creek Panels 34P-50P Blacklick Creek Lateral D Panel 51P Blacklick Creek Lateral G-B Panel 52P Blacklick Creek Lateral K Panels 53P-54P Blacklick Creek Tributary C Panel 55P Brown Run Panels 56P-59P Clover Groff Ditch Panels 60P-62P Coble-Bowman Ditch Panels 63P-64P Cosgray Ditch Panels 65P-70P Cramer Ditch Panels 71P-75P Dry Run Panels 76P-79P Blau Ditch Panels 79P-81P Dysar Ditch Panel 82P Early Run Panels 83P-85P French Run Panels 86P-87P French Run (Lateral G-A) Panels 88P-89P Table of Contents - Volume 2 - continued EXHIBITS - continued Exhibit 1 - Flood Profiles - continued Georges Creek Panels 90P-92P Grant Run Panels 93P-95P Orders & Wallace Ditch Panel 95P Grove City Creek 1 Panel 96P Mulberry Run Panels 96P-99P Grove City Creek 2 Panels 100P-101P West Water Run Panel 101P Haines Ditch Panel 102P Hamilton Ditch Panels 103P-105P Hayden Run Panels 106P-109P Faust County Ditch Panel 109P Hellbranch Run Panels 110P-112P McCoy Ditch Panel 112P Indian Run Panels 113P-114P North Fork Indian Run Panels 114P-118P Lisle Ditch Panel 119P Little Darby Creek Panel 120P Little Walnut Creek Panels 121P-125P Marsh Run Panels 126P-127P Baumgardner Ditch Panels 127P-128P Martin Grove Ditch Panel 129P Table of Contents - Volume 3 - April 21, 1999 EXHIBITS - continued Exhibit 1 - Flood Profiles - continued Mason Run Panels 130P-134P Molcomb Ditch Panels 135P-140P Olentangy River Panels 141P-143P Patzer Ditch Panels 144P-145P Plum Run Panels 146P-149P Plum Run Tributary Panels 150P-152P Powell Ditch Panel 153P Rhodes Ditch Panel 154P Rocky Fork Ditch Panels 155P-158P Scioto Big Run Panels 159P-162P Scioto River Panels 163P-169P Scioto River Divided Flow Reach Panel 170P Snyder Run Panels 171P-172P South Fork Dry Run Panel 173P South Fork Georges Creek Panels 174P-175P South Fork Indian Run Panels 176P-186P Spring Run Panels 187P-190P Sugar Run Panels 192P-196P Swisher Creek Panels 197P Table of Contents - Volume 3 - continued EXHIBITS - continued Exhibit 1 - Flood Profiles - continued Sycamore Run Panels 198P-199P Tri-County Ditch Panel 200P Tudor Ditch Panels 201P-205P Turkey Run Panels 206P-207P Tussing-Bachman Ditch Panels 208P-209P Bush Ditch Panels 209P-210P Utzinger Ditch Panel 211P Georges Creek Overland Flow Panel 212P Exhibit 2 - Flood Insurance Rate Map Index Flood Insurance Rate Map 1Note to users: Flood Profile 191P was removed to reflect the removal of the Delaware County portion of the City of Westerville Figure J-5. Digital Base Map Source Description Example Figure J-6. CCO Meeting Dates for Pre-Countywide FISs Table Figure J-7. Streams Studied by Detailed Methods Table Figure J-8. Scope of Study Table Figure J-9. Stream Name Changes Table Figure J-10. Historical Tide Gage Water Level Records Table Figure J-11. Manning's "n" Values Table Figure J-12. Transect Schematic Figure J-13. Community Map History Table Guidelines and Specifications for Flood Hazard Mapping Partners J-2 Section J.1 February 2002 Edition Section J.3 J-17 February 2002 Edition Section J.4 J-23 February 2002 Edition Section J.5 J-43 February 2002 Edition J-44 Guidelines and Specifications for Flood Hazard Mapping Partners Section J.5 J-52 February 2002 Edition 1 Section J.5 J-69 February 2002 Edition