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Mapping and Map Changes

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  1. NFIP National Flood Insurance Program Administered by FEMA Mapping and Map Changes

  2. Topics • Flood Insurance Studies and Flood Maps • Flood Studies Initiated by FEMA • Map Corrections and Maintenance

  3. Flood Insurance Studies provide technical information for: Adoption of floodplain management measures required for community participation in the NFIP Development of flood-risk information needed to establish flood insurance premiums The Purpose of Flood Insurance Studies

  4. Technical Information in the FIS... • An appraisal of a community’s flood problems • Estimates of flood-flow frequency (10, 50, 100, and 500-year return intervals) • Flood elevation profiles

  5. ...Technical Information in the FIS • Floodplain boundary delineations • Data to delineate floodways in some communities • Establishment of insurance risk zones

  6. Flood Insurance Study Products • Final Report • Flood Insurance Rate Map

  7. Flood Insurance Study Report • Written text • Figures • Floodway data tables • Flood profiles

  8. Definition of Floodway “...means the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than one foot.” Also referred to as the “Regulatory Floodway.”

  9. FLOODWAY SCHEMATIC FLOODWAY 1 FT MAXIMUM SURCHARGE

  10. Floodway Data Table

  11. Flood Insurance Study - Level of Detail... Approximate Study • Delineates “100-year” floodplain boundaries • Does not determine base flood elevations

  12. ...Flood Insurance Study - Level of Detail Detailed Study • Determines BFEs or depths of flooding • Delineates the boundary of the “100-year” floodplain

  13. Flood Maps • Flood Insurance Rate Map • Flood Boundary Floodway Map

  14. Common physical features, such as major highways, secondary roads, railroads, etc. Graphic representation and spatial distribution of flood hazard areas Flood Insurance Rate Maps show: Flood Insurance Rate Maps...

  15. Flood insurance risk zones Base Flood Elevations Floodways (newer Z-fold FIRMs) Other related data such as reference marks ...Flood Insurance Rate Maps

  16. FIRM are used for... • Identifying the boundaries of Special Flood Hazard Areas • Determining the Base Flood Elevation at a specific site (if it lies on or near a cross section)

  17. ...FIRM Uses • Locating properties in relation to the SFHA • Locating regulatory floodways Note: Older FIRMs do not show floodways. The floodways are printed on a separate Flood Boundary and Floodway Map.

  18. Flood Insurance Rate Map Panel Information • General Map Panel Information • Cover • Legend • Notes • Flood Zones

  19. NATIONAL FLOOD INSURANCE PROGRAM NATIONAL FLOOD INSURANCE PROGRAM FIRM FLOOD INSURANCE RATE MAP FIRM FLOOD INSURANCE RATE MAP CITY OF FLOODVILLE, CALIFORNIA PANEL 0001 OF 0004 CITY OF FLOODVILLE, CALIFORNIA MAP INDEX COMMUNITY-PANEL NUMBERS 060001 0001 C MAP REVISED MAY 16, 1994 Federal Emergency Management Agency COMMUNITY-PANEL NUMBERS 060001 0001-0004 MAP REVISED JUNE 5, 1996 Federal Emergency Management Agency

  20. COUNTY WIDE MAPS PANEL 0310 D MAP INDEX FIRM FLOOD INSURANCE RATE MAP FIRM FLOOD INSURANCE RATE MAP RIVER COUNTY, CALIFORNIA AND INCORPORATED AREAS PANEL 0310 OF 0520 (SEE MAP INDEX FOR PANELS NOT PRINTED) RIVER COUNTY, CALIFORNIA AND INCORPORATED AREAS (SEE TABLE SHOWN ABOVE FOR LISTING OF COMMUNITIES) MAP INDEX CONTAINS COMMUNITYNUMBERPANELSUFFIX FLOODVILLE 060001 0310 D RIVER COUNTY 060002 0310 D UNINCORPORATED AREAS PANELS PRINTED: 75, 150, 175, 300, 310, 320, 325, 330, 335, 340, 345, 375, 485, 495, 505, 510, 515, 520 MAP NUMBER 06001C0000 MAP REVISED: JUNE 5, 1996 Federal Emergency Management Agency MAP NUMBER 06001C0310 D MAP REVISED: MAY 16, 1994 Federal Emergency Management Agency

  21. LEGEND SPECIAL FLOOD HAZARD AREAS INUNDATED BY 100-YEAR FLOOD ZONE A ZONE AH ZONE AO ZONE A99 ZONE V ZONE VE FLOODWAY AREAS IN ZONE AE OTHER FLOOD AREAS ZONE X OTHER AREAS ZONE X ZONE D Boundary Dividing SFHA Zones... LEGEND... FLOOD BOUNDARY FLOODWAY BOUNDARY ZONE D BOUNDARY 513 BFE Line; Elevation in Feet* DD Cross Section Line (987) BFE in Feet Where Uniform Within Zone* RM7 Elevation Reference Mark X *Referenced to the National Geodetic Vertical Datum of 1929

  22. NOTES This map is for use in administering the National Flood Insurance Program; it does not necessarily identify all areas subject to flooding particularly from local drainage sources of small size, or all planimetric features outside Special Flood Hazard Areas. Areas of special flood hazard (100-year flood) include Zones A, A1-30, AE, AH, A99, V, V1-30, and VE. Boundaries of floodways were computed at cross sections and interpolated between cross sections. The floodways were based on hydraulic considerations with regard to requirements of the Federal Emergency Management Agency. Floodway widths in some areas may be too narrow to show to scale. Floodway widths are provided in the Flood Insurance Study Report. NOTES... Coastal base flood elevations apply only landward of the shoreline. For adjoining map panels see separately printed Map Index. MAP REPOSITORY Building Department City of Floodville Floodville, California 96580 (Maps available for reference only, not for distribution.) INITIAL IDENTIFICATION JUNE 7, 1984 FLOOD HAZARD BOUNDARY MAP REVISIONS: JUNE 11, 1986 DECEMBER 26, 1988 APRIL 12, 1989 FLOOD INSURANCE RATE MAP EFFECTIVE: MAY 17, 1991

  23. NOTES... FLOOD INSURANCE RATE MAP REVISIONS: MAY 16, 1994 Map revised to increase base flood elevations, to add base flood elevations, to change zone designations, and to update map format. To determine if flood insurance is available, contact an insurance agent or call the National Flood Insurance Program at (800) 638-6620. APPROXIMATE SCALE IN FEET 1000 0 1000 N

  24. How to use the FIRM... • Find the correct panel using the Map Index • Note: Map Indexes are only printed for communities with more than one FIRM panel • Find the general location of the site/property

  25. …How to Use the FIRM... • Find the specific location of the property by using the map scale on the legend and referencing to a physical feature such as a bridge, road intersection, etc. • Determine the flood zone

  26. ...How to use the FIRM • If available and if the site/property is at or near a cross section, determine the BFE or depth using the FIRM. NOTE: If the site/property is between cross sections, then use the flood profiles in the Flood Insurance Study Report to determine the BFE.

  27. Sample Map Index 0001C 0002B 0004D 0003B General Area of Property

  28. FIRM Panel 0001C - General Location Sutter Blvd. Fort Ross Ave. ZONE AE Monterey Ave. 532 X RM1 531 ZONE X E D Vallejo Ave. Sonoma Ave. Green River CORPORATE LIMITS LIMIT OF DETAILED STUDY 530 ZONE X 529 Fremont St. C Larkin St. Bidwell St. 528 ZONE A Alvarado Ave. B A

  29. FIRM Panel 0001C - Specific Location N Approximate Scale In Feet 500 0 500 Sutter Blvd. Fort Ross Ave. ZONE AE The structure is located on Vallejo Ave. 200 feet upstream of the Sutter Blvd. and Vallejo Ave. Inter- section. Monterey Ave. 532 X RM1 531 ZONE X E D Vallejo Ave. Sonoma Ave. Green River CORPORATE LIMITS LIMIT OF DETAILED STUDY 530 ZONE X 529 Fremont St. C Larkin St. Bidwell St. 528 ZONE A Alvarado Ave. 200 feet B A

  30. Flood Boundary Floodway Map • Map Panel Information • Cover • Key • Notes

  31. NATIONAL FLOOD INSURANCE PROGRAM NATIONAL FLOOD INSURANCE PROGRAM FLOODWAY FLOOD BOUNDARY AND FLOODWAY MAP FLOODWAY FLOOD BOUNDARY AND FLOODWAY MAP CITY OF FLOODVILLE, CALIFORNIA PANEL 0001 OF 0004 CITY OF FLOODVILLE, CALIFORNIA MAP INDEX COMMUNITY-PANEL NUMBERS 060001 0001 C MAP REVISED MAY 16, 1994 Federal Emergency Management Agency COMMUNITY-PANEL NUMBERS 060001 0001-0004 MAP REVISED JUNE 5, 1996 Federal Emergency Management Agency

  32. KEY TO MAP 500-Year Flood Boundary 100-Year Flood Boundary FLOODWAY FRINGE FLOODWAY 100-Year Flood Boundary 500-Year Flood Boundary Approximate 100-Year Flood Boundary Cross Section Line D D Elevation Reference Mark RM7 X River Mile M1.5

  33. NOTES TO USER Boundaries of the floodways were computed at cross sections and interpolated between cross sections. The floodways were based on hydraulic considerations with regard to requirements of the Federal Emergency Management Agency. This map was prepared to facilitate floodplain management activities only; it may not show all special flood hazard areas in the community or all planimetric features outside of the floodplain. Refer to the latest official Flood Insurance Rate Map for any additional areas of special flood hazard. Floodway widths in some areas may be too narrow to show to scale. Floodway widths are provided in the Flood Insurance Study Report. NOTES TO USER... For adjoining map panels, see separately printed Index to Map Panels. APPROXIMATE SCALE IN FEET 1000 0 1000 N

  34. Sample Flood Boundary and Floodway Map Index 0001C 0002B 0004D 0003B*** General Area of Property ***PANEL NOT PRINTED

  35. FBFM Panel 0001C - General Location Floodways are not printed on older FIRM panel sets. Instead, Floodways are shown on a separate Flood Boundary and Floodway Map set. The regulatory floodway is the unshaded area of the SFHA. Sutter Blvd. Fort Ross Ave. Monterey Ave. X RM1 E D Vallejo Ave. Sonoma Ave. Green River CORPORATE LIMITS LIMIT OF DETAILED STUDY Fremont St. C Larkin St. Bidwell St. Alvarado Ave. B A

  36. Exercise:Map Reading

  37. Background • There are three properties that your community is considering for construction of a new fire station. The property locations are designated as Sites 1, 2, and 3.

  38. Problem Statement... • Using the following FIRM and flood profile, determine for each site: • 1. The insurance risk zone • 2. Is any of the property within the Regulatory Floodway?

  39. ...Problem Statement • 3. Estimate the Base Flood Elevation at the upstream end of the property (to the nearest tenth of a foot) • 4. Which site is best suited for the project?

  40. ZONE X ZONE X ZONE AE P IMPERIAL BLVD Site 2 195 WEST ST 48 O Site 3 N MAIN ST 194 M Q A ST L 193 ZONE X P FRONT ST O CORPORATE LIMITS 192 191 ZONE AE 190 N Site 1 Approximate Scale In Feet 500 0 500 RIVERVIEW DR N ZONE X L M

  41. ZONE X ZONE X Zone AE Partially in floodway BFE 193.5 IMPERIAL BLVD Site 2 195 WEST ST 48 ZONE AE Zone X Not in floodway No BFE Best site for a critical facility! Site 3 MAIN ST 194 Q A ST 193 ZONE X P FRONT ST Zone AE Not in floodway BFE 191.1 O CORPORATE LIMITS 192 191 ZONE AE 190 N Site 1 Approximate Scale In Feet 500 0 500 RIVERVIEW DR N ZONE X M L

  42. Flood Studies Initiated By FEMA • Restudy • Limited Map Maintenance Program Study

  43. Restudy... • Requested by Community • Paid for by FEMA • Develops BFEs and floodways along previously unstudied flooding sources

  44. …Restudy • Updates previously studied flooding sources to reflect current conditions • Encourages cost-sharing by state, community, or other agencies • Established on a benefit/cost basis

  45. Limited Map Maintenance Program Study... • Requested by the Community • Paid for by FEMA • Develops BFEs and floodways along previously unstudied flooding sources