Flood Map Production
Considerable efforts are required in order to update floodplain maps. The Federal Emergency Management Agency (FEMA) has created a set of standards called "Guidelines and Specifications for Flood Hazard Mapping Partners" that outline the specifications for creating new digital flood maps.
Generally, flood map, or Digital Flood Insurance Rate Map (DFIRM), production can be split into three phases: scoping, production and adoption.
The Scoping phase can be further divided into five distinct phases.
- Data Collection and Research - The mapping partner gathers existing flood hazard information from previous Flood Insurance Study (FIS) reports and Flood Insurance Rate Maps (FIRMs), mapping needs identified by FEMA, claims history and letters of map change. Available state and federal Geographic Information System (GIS) data sets for the mapped county are researched and assessed. Information is compiled and translated onto a county scoping map.
- Community Meetings / Mapping Needs - The mapping partner meets with local floodplain administrators and community officials to assess reasonableness of existing flood hazard information, identify additional mapping needs, determine availability of local GIS and engineering data. The availability of other floodplain studies by others is also explored for potential leverage into the countywide DFIRM update. The meeting is an integral part of FEMA's outreach initiative to improve overall accuracy and usefulness of updated FIRMs.
- Mapping Activity Statement (MAS) - Information gathered during the data collection and community meeting phases is used to finalize the MAS. The MAS is the scope of mapping activities for the county and identifies the mapping partner's responsibilities, schedule and detailed breakdown of stream limits to be studied.
- Finalize Project Costs - Based on the mapping needs outlined in the MAS, countywide mapping project costs are finalized. Costs include estimates of the Cooperating Technical Partner (CTP) match and provide the basis for FEMA funding and project management tracking by the National Service Provider (NSP).
- Obtain FEMA Budget Approval and Notice to Proceed - Map modernization funding is based on the federal fiscal year Oct. 1 to Sept. 30). Typically, 60 percent of each FEMA region's budget must be allocated by June 30 and 100 percent of the budget by Sept. 30. The deadline for a specific county's MAS and budget will depend on the region's priority preference for CTP funding.
The production phase can be further divided into six distinct phases.
- Data Acquisition and Preparation - The study contractor will determine the "best available data" for use in the DFIRM based on information collected during scoping and will format required data sets to FEMA's specifications. Data certifications and distribution agreements are required for each data source.
- Hydrology and Hydraulics (new studies) - Detailed studies (Zone AE) represent the most detailed flood hazard information for an area and are warranted in flood prone areas with a history of flood loss or in urban areas where base flood elevations (BFEs) are needed to prevent future flood loss. Approximate studies (Zone A) identify flood risk hazards for the 1 percent annual chance flood but do not contain BFEs or other detailed flood hazard information. Approximate studies are used in rural areas where flood hazard information is needed but where detailed studies are not warranted. In general, approximate studies can be performed at about one-third of the cost of detailed studies.
- Redelineate Existing Effective Detailed Studies - Detailed study areas (Zone AE) from the existing effective FIRMs are translated onto the DFIRM by a process called redelineation. Redelineation involves reprojecting the published Base Flood Elevations (BFEs) from the flood profile onto updated topographic information identified during the scoping phase. Floodplain boundaries will likely change, but base flood elevations will not.
- Summary of Map Actions (SOMA) - LOMCs (Letters of Map Change) are FEMA's instrument to allow changes to the FIRM. When FIRMs are updated, LOMCs are incorporated into the new FIRM. The SOMA identifies how each LOMC was affected by the FIRM update.
- DFIRM Cartographics and FIS Preparation - The standards outlined in "Guidelines and Specifications for Flood Hazard Mapping Partners" are applied to ensure uniformity in the new FIRMs. Appendix J summarizes the cartographic and formatting requirements for the DFIRMs. Appendix L summarizes the technical requirements for the FIS report. Appendix K summarizes the technical requirements for the digital DFIRM database.
- Mail Preliminary DFIRM and FIS - At the conclusion of the production phase, a hard copy of preliminary DFIRMs, SOMA and FIS report are mailed to the local communities within the study county. Copies of the preliminary mailing are also provided to the state National Flood Insurance Program (NFIP) coordinator and FEMA.
The Adoption phase can be further divided into six distinct phases.
- Preliminary DFIRM Community Coordination (PDCC) Meeting - Approximately 30-45 days after the preliminary DFIRM mailing, a meeting between local officials, the state, the study contractor and FEMA is held in the study county. This meeting further outlines the techniques used in DFIRM production and allows community officials to comment on the maps prior to the 90-day appeal period.
- Published Notifications - If no significant issues were identified during the PDCC meeting, FEMA's community coordination officer will authorize initiation of the 90-day statutory appeal period. Two notifications of the proposed BFE changes and 90-day statutory appeal period must be published in the local newspaper. In addition, the notification is published in the Federal Register.
- 90-Day Appeal Period - An appeal is a formal objection to proposed BFEs submitted by a community or individual resident based on data that show the proposed BFEs are scientifically or technically incorrect. The 90-day appeal period is the statutory period, beginning on the date of second publication of the proposed BFEs in the local newspaper, during which community officials and individual residents may appeal proposed BFEs.
- Letter of Final Determination - The Letter of Final Determination (LFD) is sent to the community. The letter is the final determination of BFEs made after the 90-day appeal period has ended and all appeals have been resolved. Final BFE determinations are published in the Federal Register.
- Final Map Preparation - After the LFD is sent, map products must be finalized and prepared for printing by the Government Printing Office (GPO). Prior to submission, digital map products are submitted to the FEMA's contractor for a series of automated quality control checks. Final DFIRMs are submitted both electronically and as large-format negatives to facilitate duplication by the GPO.
- Map Adoption - The GPO will distribute final maps to the affected communities. The effective date of the map is the date that all legal sanctions of the NFIP apply. Prior to the effective date, community ordinances must be revised to reference the new maps and FIS. Failure to do so will result in possible suspension of the community from the NFIP.
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