410 Flood Hazard Mapping
400 Mapping and Regulations

410
Flood Hazard Mapping

Accurate flood hazard mapping is an important first step in creating a robust flood management system.

412.a
New study (NS)

Does your community have the capacity to conduct additional mapping studies?

Level of effort = high

Overview

While Flood Insurance Rate Maps (FIRMs) have detailed data, sometimes they do not incorporate your community's unique flood hazards. This can be attributed to changes in flood conditions since the FIRM was created, or from hazards like alluvial fans and subsisdence not being mapped as part of the Flood Insurance Study. Through element 412.a, your community can receive credit for mapping flood risk areas not included on the Flood Insurance Risk Map (FIRM) by conducting a new flood study. In other words, you can get credits for providing more data on flood risk than FEMA provides.

The study can include mapping an approximate A or V Zone in a B, C, D, or X Zone (revealing a new regulatory floodplain) or mapping flood elevations for a sites undergoing development. Credit is awarded under this element if:

  • The submitted study creates a Base Flood Elevation (BFE) where there was no elevation shown on the Flood Insurance Rate Map (FIRM), or
  • The submitted study creates a Base Flood Elevation (BFE) in A, AE, V, and VE zones higher than the Base Flood Elevation (BFE) shown on the Flood Insurance Rate Map (FIRM).
  • Your community uses the map in its development regulations.
  • The study uses a mapping technique approved by FEMA or an ISO Technical Reviewer.
  • Any study impacting a stream or shoreline is submitted to FEMA in order to revise the local Flood INsurance Rate Map (FIRM).

Because the intent of this element is to encourage more fine-grained flood risk assessment, you do not get credit if the map is created based on minimum National Flood Insurance Program (NFIP) requirements, if your community does not regulate to the map, if there is no identified regulatory floodplain, or if the new Base Flood Elevation (BFE) is lower than FEMA’s Base Flood Elevation (BFE).

Considerations

This element is complex, engineering and mapping expertise are required. Additionally, studies might require the approval of your community's governing body.

Documentation

In broad strokes, proof that a new study has been conducted is required for documentation. More specifically, you must provide:

  • A copy of the study and/or flood hazard map
  • Documentation of the local laws and ordinances that demonstrate the adoption of the flood study or required flood elevations
  • Permit records showing the new data
  • A map showing the area covered by the new studies with the appropriate MAP acronyms marked (for example, "MAP#1")
  • Evidence that study was submitted to FEMA (ex: an email or letter)
  • A statement that the study technique is listed in Guidance Documents and Other Published Resources or, if the study utilized an alternative technique, a description of the technique used
  • Calculations showing how the Special Flood Hazard Area (SFHA) and the New Study area were calculated

Credit Calculation

Max: 350, including any of the following:

Element Maximum Credit
Approximate A or V Zone 70
Flood elevations and floodway for sites undergoing development 120
Flood elevations for sites undergoing development 120
Flood elevations and floodway for sites undergoing development 160
New length of shoreline 260
A new study with a new floodway, coastal velocity zone, or one that converts Coastal A to V Zones 350

The impact adjustment in this element is calculating the a ratio of the impacted area divided by the Special Flood Hazard Area (SFHA).

Areas Impacted / SFHA

As an alternative, you can use an Optional Minimal Value, which is 10% of the maximum possible credits.

412.b
Leverage (LEV)

Does your community have the financial resources to fund new studies without FEMA support?

Level of effort = low

Overview

This element is a multiplier that awards more credits to communities that fund New Studies through non-FEMA resources.

Considerations

Because this element is a multiplier, element 412.a. New Study (NS) is a prerequisite. There are several ways to calculate the ratio for this multiplier. You should determine which ratio calculation will result in the highest multiplier.

Documentation

To document this element, you must provide documentation of how the ratio was calculated.

Credit Calculation

This is a New Study multiplier with a range from 0 to 1. You receive a multiplier of 0 if FEMA funded the study, and a multiplier of 1 if the study was locally funded. Generally, the multiplier can be determined using the following calculation:

(Non-FEMA share of cost / Total cost )*(credits award under NS)

Alternatively, if a topographic map was used, your multiplier can be calculated using the following calculation:

NS(0.27)

If new study data was used in addition to a topographic map, use the following multiplier:

NS (0.27+0.22)

412.c
State review (SR)

Credits can be awarded for independent QA of New Studies (NSs) conducted in your community.

Level of effort = high

Overview

Your community can receive credit if an outside agency performs an independent quality assurance review (usually this is a state agency, as required by your state's laws) of your New Study (NS). These reviews can include hydrology, hydraulics, or mapping. States that have review procedures that are eligible for credit under this element are New Jersey, Indiana, Michigan, Minnesota, Wisconsin, and Illinois.

Considerations

The review conducted in fulfillment of this element cannot be funded by FEMA.

Documentation

For credit under this element, you must provide documentation that the state or corresponding responsible agency accepted the findings of the review. This will usually take the form of a letter.

Credit Calculation

Max: 60, including any of the following:

Element Maximum Credits
Flood elevations at a site undergoing development 20
New length of shoreline 45
New study with a new floodway, new coastal velocity zone, or one that converts Coastal A to V Zones 60

412.d
Higher study standards (HSS)

FEMA's study standards are only a baseline. You can receive points for using higher study standards.

Level of effort = highCredit for this element is required for CRS Class 1

Overview

Your community can receive credit for using higher study standards than those FEMA uses. Some examples include:

  • Calculating 100-year discharge using a factor of safety (at least a 25% increase)
  • Calculating hydrology using future conditions in land use (a fully developed area)
  • Calculating hydrology using future conditions in climate (sea level rise at least as high as NOAA’s intermediate-high projections for 2100)
  • Mapping additional freeboard on top of the base flood elevation (at least one foot).

If there are other higher study standards you anticipate using, you can submit these to your CRS Specialist for review.

Credit is awarded under this element if:

  • The submitted study standards are used to map the area impacted by them
  • Your community uses the map in its development regulations.
  • The study uses a mapping technique approved by FEMA or an ISO Technical Reviewer.
  • Any study impacting a stream or shoreline is submitted to FEMA in order to revise the local Flood INsurance Rate Map (FIRM).

Considerations

You can receive credit for this element in areas where you don’t receive credit for 412.a New Study (NS).

Documentation

To document this element you must provide evidence of the higher study standards including:

  • The text from the Flood Insurance Study if FEMA used the information or the ordinance adopting the higher standard
  • The map indicating impacted areas with MAP acronyms (ex: "MAP#1", "MAP#2", as appropriate)

Credit Calculation

Max: 200, including any of the following:

Element Maximum Credits
Delineating an approximate A Zone 75
Flood elevations of a site undergoing development 110
New shorline 200

You can submit up to 3 study standard for credit. The impact adjustment in this element can be calculated using this ratio:

Areas Impacted / Special Flood Hazard Area (SFHA)

As an alternative to the impact ratio, you can use the Optional Minimum Value: 10% of the maximum possible points. Do this if you are unable to calculate the impact ratio or if the ratio is less than 0.1.

412.e
More restrictive floodway standard (FWS)

How are you regulating your floodways?

Level of effort = high

Overview

Your community can receive credit for defining, mapping, and adopting a more restrictive floodway standard. Like the other elements in 410, you cannot receive credit for solely enforcing the minimum National Flood Insurance Program (NFIP) requirements. You will also need to map the area effected and utilize the map in your development regulations. The technique you use to conduct the study must be approved by FEMA or, alternatively, an ISO Technical Reviewer. If the study impacts a stream or shoreline, you must make it available to FEMA so that the local Flood Insurance Rate Map (FIRM) can be revised.

Considerations

The requirements for this element can prove to be politically complex and you can't pass the buck: you won't receive credit for adopting an ordinance that requires each new development to engage in floodway analysis in order to receive a permit.

Documentation

To receive credit for this element, you must provide:

  • A copy of the data table and text from the Flood Insurance Study or other floodplain study describing the floodway standards
  • If the study is not included in the current Flood Insurance Study, you must provide the map, the standard, and the ordinance for review

Credit Calculation

Max: 140

Some states currently have floodway standards that qualify for specific CRS credits so if your community is in one of those states, you get credit automatically: If you’re in Montana, New Jersey, or Colorado you can receive 60 credits. If you’re in Indiana you can receive 105 credits. If you’re in Illinois, Michigan, Minnesota, or Wisconsin you can receive 140 credits.

The impact adjustment in this element can be calculated using the following ratio:

Areas Impacted / Special Flood Hazard Area (SFHA)

Alternatively, you can use 10% of the maximum possible credits if you are unable to calculate the ratio, or the impact adjustment ratio is less than 0.1.

412.f
Mapping of special flood-related hazard areas (MAPSH)

Mapping and regulating coastal erosion and/or tsunami hazards can get your community additional credits.

Level of effort = high

Overview

This element is comprised of two parts:

Mapping coastal erosion hazard areas (MCE): You can receive credit for mapping coastal erosion or conducting erosion rate analyses.

Mapping tsunami hazard areas (MTS): Credits are also awarded for mapping tsunami hazard areas to aid in management and planning. Tsunami hazard maps must be based on a scientific study.

For both subelements, in addition to mapping, you will also need to:

  • Regulate the identified areas
  • Put regulations in place to prevent future damage
  • For MCE: Identify a coastal erosion hazard area (30 to 100 years in the future) using FEMA’s standards.

Considerations

This element is tied to Activity 430. In order to receive credits you are required to receive at least 20 credits for submitted regulations under Activity 430.

Documentation

To document your work for this element, you must provide:

  • A map showing the special flood-related hazards and the Special Flood Hazard Area (SFHA)
  • A description of the mapping technique utilized for this element
  • Documentation of the associated regulations under Activity 430

    • A description of the enforcement procedures for the regulations
  • For annual recertification, you will need to include a letter from an engineer verifying that the data used for mapping is still current

Credit Calculation

Max:100, including any of the following:

Element Maximum credits
Mapping Coastal Erosion Hazard Areas (MCE) - Mapping the entire shoreline 50
Mapping Coastal Erosion Hazard Areas (MCE) - Requiring site-specific studies 25
Mapping Coastal Erosion Hazard Areas (MCE) - Adopting a regulatory map for the next 30 years (without erosion rates) 10
Mapping Coastal Erosion Hazard Areas (MCE) - Adopting a regulatory map for the next 100 years (without erosion rates) 25
Mapping and regulating tsunami hazards (MPS)- Mapping areas outside of the Special Flood Hazard Area (SFHA), or areas where the tsunami elevation is higher than the Base Flood Elevation (BFE) 50

The impact adjustment is calculated by dividing the coastline mapped by the total coastline in your community.

This CRS guide was produced by CRS professionals and Certified Floodplain Managers to help you navigate the Community Rating System. It is not meant to replace FEMA's official CRS Coordinator's Manual, nor should it supersede the instructions given by your ISO/CRS Specialist.

For additional resources, visit https://crsresources.org/ .