1. CHAPTER 3 MAPS AND MAP CHANGES

2. Flood Maps: It’s Your Job to Understand Them
Read and understand the FIRM, and;
Interpret the Flood Insurance Study.

3. Riverine Floodplains Definitions………
Floodway: 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.

4. Riverine Floodplains Definitions………
Floodway fringe: that area of the floodplain on either side of the regulatory floodway where encroachment may be permitted without additional hydraulic and/or hydrologic analysis.

5. Riverine Floodplains

6. Floodway Schematic FLOODWAY + FLOODWAY FRINGE = 100 YEAR FLOODPLAIN
SURCHARGE
FLOODWAY + FLOODWAY FRINGE = 100 YEAR FLOODPLAIN
SURCHARGE NOT TO EXCEED 1.0 FOOT
In the floodway - Before a local floodplain permit can be issued, a “no rise’ certification form must be submitted. You may need a qualified engineer to make sure your proposed project won’t increase flooding on other properties.

7. Coastal Floodplains Definitions………
Coastal High Hazard Area: an area of special flood hazard extending from offshore to the inland limit of a primary frontal dune along an open coast and any other area subject to high velocity wave action from storms or seismic sources. The area is designated on the FIRM as Zone V1 – V30, or VE or V.

8. Coastal Floodplains Definitions………
Coastal A Zone: the portion of the SFHA landward of a V zone…which may be subject to wave effects, velocity flows, erosion, scour, or combinations of these forces and are treated as V zones.

9. Coastal Floodplain

10. TYPES OF NFIP MAPS

11. How Do They Make Those EXCELLENT Floodplain Maps?
So...how do they make those EXCELLENT floodplain maps.
First, you need to know a watershed. How much water flows into a stream at any given point. Then engineers add in the land use (urban or rural) and average rainfall data.
Then, engineers determine the cross section of a stream. How wide the river valley is..how much water can be pushed through that valley.
Lastly, when all this data is put together, engineers can accurately estimate the flood height and as such, determine the floodplain.

12. Components of Flood Maps
Title box
Community name
Panel number
Community number
Panel suffix
Effective/revision date

13. Components of Flood Maps
Map Index

14. Approximate Floodplain Map (Flood Hazard Boundary Map)
Shows approximate location of flood risk.
Detailed information (ground elevation and flood height) are required to make accurate determinations
The oldest maps in the FEMA family have none of this data.
The maps show, based on the best available information, where the floodplain MIGHT be.
In order to build in this type of area, detailed information such as ground elevation and flood elevation must be provided by the developer.

15. Flood Insurance Rate Map (FIRM)
Base Flood Elevation (BFE) Water Surface elevation (in feet) of the base flood at specific locations
Elevation Reference Marks (RM) Points for which ground elevation data have been established and recorded on the FIRM
Flood Hazard Zones Zone A, Zone A1–A30, and Zone AE – 100-year or base flood Zone B – year flood Zone C or X – All other areas
The most common map is the Flood Insurance Rate Map (FIRM).
The FIRM has a wealth of information:
*The base (or 100-year) flood elevation
*Elevation reference marks
*Flood zones *A *B *C

16. Components of Flood Maps (cont.)
FIRM “Old Format”

17. Flood Insurance Rate Map
(old format)
Base Flood Elevations
Reference Marks
Zone A
Zone B
Zone C

18. Flood Boundary and Floodway Map (old format)
Stream channel
Floodway
Floodway fringe
Approximate A Zone
Elevation reference mark
Cross section

19. Flood Insurance Rate Map (New Format)
Unshaded X Zone
Zone AE
Floodway
Floodway fringe
Cross section
Base flood elevation
Shaded X Zone
Zone boundary
Approximate A Zone

20. Coastal Floodplain Map
A#, AE, A, AO Zones
V#, VE Zones

21. Levels of Detail in Floodplain Delineations
Two levels of Studies………
Detailed Coastal: Based on detailed engineering methods, near-shore bathymetry, and coastal storms.

22. Coastal Floodplain Map
Coastal Barrier Resource Act (CoBRA) of 1982
Coastal Barrier Improvement Act of 1990
Areas subject to certain flood coverage restrictions. The NFIP is prohibited from writing flood insurance policies on new or substantially improved buildings in these areas.

23. Coastal Barrier Zones

24. Floodplain Maps
Special FIRM Formats
Lakes

25. Floodplain Maps Shallow flooding AO -ponding AH – sheet flow ZONE AO
(DEPTH 2’)

26. Digital Flood Insurance Rate Maps The Next Generation
Here is an example of an older firm for Jelkes Creek in Kane County alongside the newer DFIRM of the same creek.
The standard base map for the new, two-color DFIRMs are orthophotos, on which flood boundaries will be shown in blue.
Using the aerial photography as the base map will help to make floodplain determinations easier.

27. The “FIRMette” Available online Scaled to use as regulatory map
Printable
Click “Map Store”
Click “Map Search”
Type in address
Click “view” map

28. Components of a Flood Insurance Study (FIS)

29. Components of a Flood Insurance Study (FIS)
Appraises a community’s flood problems
Establishes flood elevation profiles
Establishes insurance risk zones
Plots floodplain boundaries
Provides data to delineate floodways in some communities

30. Components of a Flood Insurance Study (FIS)
Flood Profile
5-8

31. Components of a Flood Insurance Study (FIS)
Floodway Data Table

32. Flood Insurance Studies (cont.) Using the Floodway Data Table
1. Locate site on the FIRM or Floodway Map

33. Flood Insurance Studies (cont.) Using the Floodway Data Table
If at a cross section, use the Floodway Data Table

34. Flood Insurance Studies (cont.) Using the Profile
If not at a cross section, use the profile

35. Flood Insurance Studies (cont.) Using the Profile
1. Locate site on the FIRM or Floodway Map
↕200 feet
McNeese Street
2. Measure the distance to a feature

36. Flood Insurance Studies (cont.) Using the Profile
3. Find the feature on the profile
4. Check the horizontal scale on the profile

37. Flood Insurance Studies (cont.) Using the Profile
Check the horizontal scale on the profile
1 square = 50 feet
200 feet =
4 squares

38. Flood Insurance Studies (cont.) Using the Profile
4. Measure the distance to the site
200 feet
(4 squares) ↔
5. Find the 100-year flood line and read the elevation on the left edge.

39. Flood Insurance Studies (cont.) Using the Profile
5. Check the scale of the left edge
200 feet
(4 squares) ↔
10 squares = 5 feet, square = ½ foot
___ __
3.2 squares
3.2 x 1/2 = 1.6
= 11.6

40. Flood Insurance Studies (cont.) Using the Profile
Double check that the elevation, does it makes sense?

41. Map Changes Sometimes the maps are just plain wrong!
Sometimes the floodplains are modified.
There is a process to correct them
So...what can a property owner do when he thinks he is well above the flood elevation.
Sometimes the maps are just plain wrong!
Sometimes the floodplains are changed by human intervention (levees or channel relocations)
The maps can be changed.

42. Effect of Map Revisions
Map revisions can change SFHA boundaries and Base Flood Elevations in a community.

43. Letter of Map Amendment (LOMA)
A letter from FEMA stating that an existing structure or parcel of land that has not been elevated by fill would not be inundated by the 1% chance flood.
(Fill is defined as material placed to raise the ground to or above the BFE.)

44. Letter of Map Amendment (LOMA)
House is shown in the floodplain
The most common situation is that the property is shown on the floodplain map, but it actually sits on an area of high ground that the mapping process missed.
But NATURAL ground elevations prove it to be higher than the flood elevation

45. Letter of Map Amendment (LOMA)
Situation:
Structure is located on NATURALLY high ground
Information needed by FEMA:
Completed MT-1 Form 1 (or MT-EZ)
This situation is called a Letter of Map Amendment (LOMA)
The structure sits on Naturally high ground.
The property owner provides FEMA with the correct elevation of the flood and the lowest grade. If the home is truely above the flood elevation. FEMA will remove the parcel by letter.
There is no cost for this process.
Cost: “free”

46. MT-EZ *Used for inadvertent inclusions only.
*Natural ground is higher than the flood elevation.

47. Conditional Letter of Map Amendment (CLOMA)
A letter from FEMA stating that a proposed structure that is not to be elevated by fill would not be inundated by the 1% chance flood if built as proposed.

48. Letter of Map Revision (LOMR)
New floodplain based on PHYSICAL modification
Fill
New stream location
What about if the actual floodplain is changed through filling or a levee or a reservoir?
This is called a Letter of Map Revision (LOMR).
Floodplain as shown on the floodplain map

49. Letter of Map Revision (LOMR)
Situation:
Physical changes to the floodplain, the floodway, or flood elevations.
Information needed by FEMA:
Detailed engineering and MT-2 Form
A LOMR is for a physical change to the floodplain.
It requires detailed engineering sent to FEMA.
LOMRs are also expensive. There is a charge for the engineering review.
Cost: not cheap

50. Map Change Processes
Fees are charged for proposals to change the FIRM by grading or filling.
5-17

51. Conditional Letter of Map Revision (Based on Fill) CLOMR-F
A letter from FEMA stating that a parcel of land or proposed structure that is to be elevated fill would not be inundated by the 1% chance flood if fill is placed on the parcel as proposed and the structure is built as proposed.

52. LOMR-F

53. Technical Bulletin 10-01

54. LOMR-F?
With a basement below BFE??
NOT in the Gulf States!
NOT while I’ve got a say!

55. LOMA/R TOLL-FREE HOTLINE 1-877-FEMA MAP (366-2627)
Inundated with calls about changing the maps from residents, insurance companies, or appraisers, etc?
Need to know the status of a current LOMA/R request?

56. Effect of Map Revisions
You must retain all versions of your FIRMs.
It is a good idea to file a ‘FIRMette’ with every permit.
Why ???

57. Effect of Map Revisions (cont.)
LOMAs and LOMRs could be invalidated by a map revision.
Contact your State NFIP Coordinator for the procedures to pass on to the affected citizens.

58. Effect of Map Revisions (cont.)
SFHA increases…new areas are subject to your ordinance.
Buildings in new SFHA are now subject to the mandatory purchase of flood insurance.

59. Letter of Determination Review
When a borrower and lender disagree on a floodplain determination during the loan process, FEMA can review the determination.
FEMA has 45-days to respond, and, by law, FEMA’s determination is final.

60. My lending institution said I’m in the floodplain and they require flood insurance on my loan/mortgage. I don’t believe I’m in a flood zone. What can I do?
All federally regulated lending institutions must review the community Flood Insurance Rate Map (FIRM) to determine if your structure is located in a Special Flood Hazard Area (SFHA). If such a determination is made, it must require the borrower to purchase flood insurance. These determinations are based on in/out (horizontal) and do not involve the vertical elevation of the structure.
If you disagree, you may request that FEMA review the lender’s determination. FEMA will review the information that the institution used and issue a letter of findings. Your request (FEMA Standard Flood Hazard Determination) must be postmarked no later than 45 days after the lender notifies you of its determination. FEMA’s responses to these requests are called LODRs and offer two basic dispositions: (1) the lender’s determination stands or (2) it is overturned. FEMA’s response does not amend or revise the NFIP map for your community.
Occasionally, a lending institution may require insurance if it determines that a part of your lot is in the SFHA. The NFIP does not insure land. However, even if you submit evidence that your building is out of the floodplain, the lender may still decide to require flood insurance on your building.

61. Letter of Determination Review (cont.)
5-19

62. Flood Map Modernization
FEMA 5-year, $1 billion national program
FEMA sets the schedule and the funding --annually updated in the Multi-Year Flood Hazard Identification Plan

63. Age of Flood Maps
70% of Illinois’ flood maps were more than 10 years old in The numbers aren’t quite so high now because new maps have been completed for several counties and communities since then.
The age of map panels is a compelling reason for map modernization. It has been nearly impossible for local officials, particularly in rapidly developing communities, to use these older maps for proper planning and development.
Many of the older maps do not accurately reflect flood hazard conditions. This can create a false sense of security and place buildings, infrastructure and individuals at risk.
Flood hazards are dynamic and may change rapidly due to community development as well as natural processes in the watershed.
As of 2002

64. Map Mod Objectives More accurate floodplain management
Up-to-date, standardized digital flood maps throughout the country
ArcGIS geo-database format
Seamless, nationwide flood layer
Internet-accessible through FEMA's Multihazard Information Platform (MIP)
The engineering models used in studies will be kept in the geo-database.
The MIP will eventually integrate data on other natural and man-made hazards as well. This will provide a broader view of risk.

65. Advantages of DFIRMs
Map revisions will be faster and easier – months instead of years
Communities will be able to use the digital flood map data with their local data, such as parcel data
The new flood risk maps will cover entire counties
If a community is located in more than one county, it will be mapped only to the county border
Accurate flood hazard data is available in a standardized GIS format throughout the country.
IDNR has expressed an interest in assuming responsibility for maintaining the state’s flood hazard data.
LOMCs can be incorporated on the digital map and the community can print out the revised map (even if the map panel is not reprinted) rather than have pages of copied LOMCs.

66. Local Participation Share base map data Review current maps for errors
Provide information on new studies or floodplain changes that may affect BFEs
Document future mapping needs
Review preliminary maps
Collect and submit appeals & protests
Adopt final maps and update local floodplain ordinance

67. Mapping Process Convert FIRM
Register (align) existing FIRM to the community base map
Digitize flood data (floodplain boundaries, cross sections, BFEs, etc.)
Convert to NAVD 1988 vertical datum
Incorporate LOMCs
This essentially fits the paper map to the base map.

68. Mapping Process Correct and Update
Validate cross section locations using FIS profile data
Align floodplains with stream locations on base map (Zone A)
Correct and update municipal boundaries and road, stream and lake names
We clean up areas where the paper map obviously does not match the base map.
Many errors will be corrected just by using a more up-to-date base map, or the new orthophotography.
You’ll have a chance later on to mark up paper map panels with any corrections you know need to be made.

69. Redelineation Example Redelineated SFHA Original FIRM SFHA
Detailed study areas (Zone AE) from the existing FIRM are translated onto the DFIRM by a process called redelineation. This involves reprojecting the published base flood elevations from the profile onto the (possibly) updated topographic information.
If the topographic data is newer, the floodplain boundaries will likely change, but base flood elevations will not.
Redelineated SFHA
Original FIRM SFHA
Cross section
Base flood elevation
LIDAR-contour lines

70. What About Areas That Need Study?
Part of the scoping process is to identify the mapping needs of a county
Areas where flood risk needs to be identified (never studied)
Areas where flood risk needs to be refined because of changes in hydrology or hydraulics—new bridges, culverts, etc.
Any other community mapping issue
These will be prioritized for future flood studies
Part of this scoping process is to collect information for FEMA about local mapping issues even if they cannot be resolved in this map update.
An example of the first item would be a missing floodplain. In an urbanizing area a flood hazard area (floodplain) has never been identified for a stream.
An example of the second item: BFE has changed because a new bridge has been built.
Once again, please describe any mapping needs on the data form, and / or mark the area on the map panels.

71. To Do Now Review current maps and note
Corrections
Changes that could affect BFEs on studied streams
New flood studies
Mapping needs
Identify and complete any study needs.
Have base maps ready for use.

72. Mississippi Flood Map Modernization Initiative

73. Mississippi Flood Map Modernization Initiative

74. Insert LA Map Mod Slides

75. Using Maps and Data Site #1. House 1. In the SFHA? 2. In the floodway?
3. What’s the BFE?
#1 ↓ ▀

76. Using Maps and Data Site #2. Store 1. In the SFHA? 2. In the floodway?
3. What’s the BFE?
#2 ↓ ▀

77. Using Maps and Data

78. Using Maps and Data Site #3. House 1. In the SFHA? 2. In the floodway?
3. What’s the BFE?
#3 ↓ ▀

79. Using Maps and Data Site #4. Shopping center (7 acres) 1. In the SFHA?
2. In the floodway?
3. What’s the BFE?
#4 ↓ ▀

80. Using Maps and Data Site #5. House #5 ↓ 1. In the SFHA?
2. In the floodway?
3. What’s the BFE?
#5 ↓ ▀

81. Using Maps and Data
Unincorporated areas

82. Using Maps and Data New flood studies
Managing Floodplain Development in Approximate Zone A Areas