Floodplain Mapping- Non-Regulatory Products
As FEMA transitions from the Map Modernization program to the Risk Mapping, Assessment and Planning (Risk MAP) program, there are new ways to use the data from Map Modernization to help communities identify potential hazards. Through Risk MAP, FEMA has developed several non-regulatory products that can assist communities with community planning, outreach, and education. These products can further identify where flooding may take place within a community. Developing the additional locations could be used to help prioritize potential mitigation actions within the community.
The non-regulatory products are grouped into two categories: Basic and Enhanced. Basic products will be produced for every Risk MAP project while enhanced products such will be produced if there is data available to support their development.
The Flood Risk Report provides stakeholders with a comprehensive understanding of flood hazard and risk exposure within their community, watershed, or county. The report parallels the Flood Insurance
Study report by providing a narrative of the flood risk assessment methodology and results. The report provides risk assessment information at theproject level, placing emphasis on risk reduction activities that may have impacts beyond the specific stream area or community. The report will also provide risk assessment information that can be incorporated into mitigation plans. The report will also include a Flood Risk Map that depicts select flood risk data for jurisdictions within the project area, emphasizing that risk reduction activities may have an impact beyond the site.
The Flood Risk Database will be the primary source to access information collected and developed during the flood risk assessment process. The Flood Risk Database parallels the Flood Insurance Rate Map database. It is a project-level database that includes flood risk assessment data collected, created, and analyzed during the flood risk project. FEMA will publish and maintain the database in a standardized form to support national, State, regional, and local distribution. Viewing tools are currently under development, to provide users without access to Geographic Information System (GIS) software, the ability to visualize and understand the multiple flood risk datasets contained within the database.
Flood Risk Assessments helps guide community mitigation efforts by highlighting areas where risk reduction actions may produce the highest return on investment. Building on the foundation of the 2010 nationwide HAZUS Level 1 Average Annualized Flood Loss (AAL) Study, basic refined HAZUS loss estimation analyses will be done for flooding sources with default HAZUS building stock information. Where local built environment data is available, enhanced HAZUS or other risk assessment analyses are possible. Communities are encouraged to pursue enhanced analysis where possible by providing FEMA with additional GIS data such as parcel data, building footprints, or elevation certificates. Communities may also provide additional funding to support analysis enhancement. The results of both the basic refined and enhanced HAZUS analysis can be incorporated into hazard mitigation plans.
The Changes Since Last FIRM dataset helps communities understand changes to their flood maps and prepare for the upcoming flood map adoption process. This product is a spatial dataset that identifies areas of floodplain and flood zone changes that have occurred since the previous flood map study. The dataset captures areas where the floodplain and floodway have increased or decreased, as well as areas where the flood zone designation has changed (e.g., A to AE). In areas where the mapped flood hazard has changed, the engineering factors that may have contributed to that change will also be identified within the dataset. The built environment affected by the change is quantified and summarized to help locate previously unidentified areas at risk.
Depth grids provide the depth of flooding for the 10% (10-yr), 4% (25-yr), 2% (50-yr), 1% (100-yr), and 0.2% (500-yr) annual chance flood events. This product is developed by subtracting the water surface elevation from the ground elevation at a given point for any given flood event. Better topography data will result in more accurate depth grids. The depth grids help people to understand not just whether their house is "in" or "out" of the floodplain but how deep the flooding will be in their area for a given flood event. The analysis grids will be used to create additional analyses that depict the percent annual chance of flooding and the percent chance of flooding over a 30-year time period in the floodplain. This product will visually depict levels of risk within the Special Flood Hazard Area.
Where data is available, there are several Enhanced products that can be requested by the local community. The dam-related products are intended to be used by the dam owner/operator, emergency management officials, and planners. These products would depict upstream impoundment areas, downstream inundation areas from a partial or full release, depth grids, flood velocity, and estimated time of flood wave arrival. This information could be used to identify structures and critical facilities that may warrant consideration for mitigation projects.
The Areas of Mitigation Interest dataset helps communities better understand the impact of multiple physical factors on the floodplain elevation and extent. An AOMI identifies areas that would benefit from mitigation measures such as repetitively flooded structures, undersized culverts, emergency routes historically impacted by flooding, and significant erosion areas.This enhanced spatial dataset, identifies conditions within a flood risk project area (watershed or otherwise) that may contribute to the severity of the flood hazard and associated losses. These conditions include areas with a history of flood claims, hydraulic or other structures that contribute to backwater (e.g., undersized culverts, bridges and dams), and areas experiencing land use change or development. By identifying these conditions within the watershed, this product will also assist communities in determining potential mitigation opportunities. If your community has any AOMIs, they can be entered online on the State Hazard Analysis Resource and Planning Portal (SHARPP) website.