FEMA has requested USGS expertise in hydraulics, hydrology, and mapping to generate flood insurance maps for New England.
Not only is flooding one of the most common and costly disasters, but flood risk can also change over time because of new development, weather patterns, and other factors. Although the frequency or severity of flood effects cannot be changed, the Federal Emergency Management Agency (FEMA) is working with partners across the Nation to identify flood risk and promote informed planning and development practices to help reduce that risk through the Risk Mapping, Assessment and Planning (Risk MAP) program.
As part of the Risk MAP program, FEMA partners with the USGS to provide communities with flood information and tools they can use to enhance their mitigation plans and take action to better protect their citizens. This work is done through flood risk projects. In the Risk MAP program, each flood risk project is tailored to the needs and capabilities of each affected community and a strong emphasis is placed on community engagement and partnerships to ensure a whole community approach to reducing flood risk and building more resilient communities.
When conducting flood risk projects, the USGS uses a watershed-based approach. Each watershed study or flood risk project takes about 50 months to complete and has four main steps: discovery, field surveying, hydrology and hydraulics, and flood risk product deliverables. Discovery is the process of data mining, collection, and analysis with the goal of conducting a comprehensive watershed study and initiating communication and mitigation planning discussions with the communities in the watershed. Field surveying is the collection of land survey data for waterbodies identified as high priority by communities during the discovery process. Data collection during field surveying is done using global navigation satellite systems methodology. Hydrology and hydraulics is the use of data collected in the field to create models and floodplain maps. The last step is working with communities and partners to finalize and release flood insurance rate maps (FIRMs) and flood insurance study (FIS) reports.
The Risk MAP program’s flood risk products complement regulatory products to provide flood risk information and support community floodplain management and hazard mitigation strategies. The flood risk products and datasets present information that can enhance hazard mitigation planning activities, especially the risk and vulnerability assessment portion of a hazard mitigation plan, and the development of risk-based mitigation strategies. Flood risk products can also help guide land use and development decisions and help support mitigation action by highlighting areas of highest risk, areas in need of mitigation, and areas of floodplain change.
More information on FEMA flood maps and the Risk MAP program can be found on FEMA’s website: https://www.fema.gov/flood-maps
Below are other science projects associated with this project.
Northeast Region Flood Science Capability Team
Below are FAQ associated with this project.
Where can I find flood maps?
FEMA is the official public source for flood maps for insurance purposes: FEMA’s Flood Map Service Center FEMA’s National Flood Hazard Layer NOAA is responsible for producing flood forecast maps that combine precipitation data with USGS streamflow data: National Weather Service - Advanced Hydrologic Prediction Service River Forecasts Long-Range River Flood Risk Coastal Inundation Dashboard: Real...
What is a 1,000-year flood?
The term “1,000-year flood” means that, statistically speaking, a flood of that magnitude (or greater) has a 1 in 1,000 chance of occurring in any given year. In terms of probability, the 1,000-year flood has a 0.1% chance of happening in any given year. These statistical values are based on observed data.
What are the two types of floods?
There are two basic types of floods: flash floods and the more widespread river floods. Flash floods generally cause greater loss of life and river floods generally cause greater loss of property. A flash flood occurs when runoff from excessive rainfall causes a rapid rise in the water height (stage) of a stream or normally-dry channel. Flash floods are more common in areas with a dry climate and...
How are floods predicted?
Flood predictions require several types of data: The amount of rainfall occurring on a real-time basis. The rate of change in river stage on a real-time basis, which can help indicate the severity and immediacy of the threat. Knowledge about the type of storm producing the moisture, such as duration, intensity and areal extent, which can be valuable for determining possible severity of the...
We had a "100-year flood" two years in a row. How can that be?
The term "100-year flood" is used to describe the recurrence interval of floods. The 100-year recurrence interval means that a flood of that magnitude has a one percent chance of occurring in any given year. In other words, the chances that a river will flow as high as the 100-year flood stage this year is 1 in 100. Statistically, each year begins with the same 1-percent chance that a 100-year...
- Overview
FEMA has requested USGS expertise in hydraulics, hydrology, and mapping to generate flood insurance maps for New England.
Sources/Usage: Public Domain.Surface Water Modeling for FEMA Flood Insurance Rate Maps. Hydrologic Technician takes a channel measurement using a Total Station on a river near St. Johnsbury, VT. Not only is flooding one of the most common and costly disasters, but flood risk can also change over time because of new development, weather patterns, and other factors. Although the frequency or severity of flood effects cannot be changed, the Federal Emergency Management Agency (FEMA) is working with partners across the Nation to identify flood risk and promote informed planning and development practices to help reduce that risk through the Risk Mapping, Assessment and Planning (Risk MAP) program.
As part of the Risk MAP program, FEMA partners with the USGS to provide communities with flood information and tools they can use to enhance their mitigation plans and take action to better protect their citizens. This work is done through flood risk projects. In the Risk MAP program, each flood risk project is tailored to the needs and capabilities of each affected community and a strong emphasis is placed on community engagement and partnerships to ensure a whole community approach to reducing flood risk and building more resilient communities.
When conducting flood risk projects, the USGS uses a watershed-based approach. Each watershed study or flood risk project takes about 50 months to complete and has four main steps: discovery, field surveying, hydrology and hydraulics, and flood risk product deliverables. Discovery is the process of data mining, collection, and analysis with the goal of conducting a comprehensive watershed study and initiating communication and mitigation planning discussions with the communities in the watershed. Field surveying is the collection of land survey data for waterbodies identified as high priority by communities during the discovery process. Data collection during field surveying is done using global navigation satellite systems methodology. Hydrology and hydraulics is the use of data collected in the field to create models and floodplain maps. The last step is working with communities and partners to finalize and release flood insurance rate maps (FIRMs) and flood insurance study (FIS) reports.
The Risk MAP program’s flood risk products complement regulatory products to provide flood risk information and support community floodplain management and hazard mitigation strategies. The flood risk products and datasets present information that can enhance hazard mitigation planning activities, especially the risk and vulnerability assessment portion of a hazard mitigation plan, and the development of risk-based mitigation strategies. Flood risk products can also help guide land use and development decisions and help support mitigation action by highlighting areas of highest risk, areas in need of mitigation, and areas of floodplain change.
More information on FEMA flood maps and the Risk MAP program can be found on FEMA’s website: https://www.fema.gov/flood-maps
- Science
Below are other science projects associated with this project.
Northeast Region Flood Science Capability Team
The USGS Northeast Region has been an active and competent force in flood-science through (1) maintenance of our streamgaging network to provide timely and accurate data to the National Weather Service, other federal (USACE and FEMA) and state agencies (Emergency Management Agencies), and the public in times of flood emergencies; (2) documentation of major floods; (3) involvement in the USGS Flood... - Multimedia
- Publications
- FAQ
Below are FAQ associated with this project.
Where can I find flood maps?
FEMA is the official public source for flood maps for insurance purposes: FEMA’s Flood Map Service Center FEMA’s National Flood Hazard Layer NOAA is responsible for producing flood forecast maps that combine precipitation data with USGS streamflow data: National Weather Service - Advanced Hydrologic Prediction Service River Forecasts Long-Range River Flood Risk Coastal Inundation Dashboard: Real...
What is a 1,000-year flood?
The term “1,000-year flood” means that, statistically speaking, a flood of that magnitude (or greater) has a 1 in 1,000 chance of occurring in any given year. In terms of probability, the 1,000-year flood has a 0.1% chance of happening in any given year. These statistical values are based on observed data.
What are the two types of floods?
There are two basic types of floods: flash floods and the more widespread river floods. Flash floods generally cause greater loss of life and river floods generally cause greater loss of property. A flash flood occurs when runoff from excessive rainfall causes a rapid rise in the water height (stage) of a stream or normally-dry channel. Flash floods are more common in areas with a dry climate and...
How are floods predicted?
Flood predictions require several types of data: The amount of rainfall occurring on a real-time basis. The rate of change in river stage on a real-time basis, which can help indicate the severity and immediacy of the threat. Knowledge about the type of storm producing the moisture, such as duration, intensity and areal extent, which can be valuable for determining possible severity of the...
We had a "100-year flood" two years in a row. How can that be?
The term "100-year flood" is used to describe the recurrence interval of floods. The 100-year recurrence interval means that a flood of that magnitude has a one percent chance of occurring in any given year. In other words, the chances that a river will flow as high as the 100-year flood stage this year is 1 in 100. Statistically, each year begins with the same 1-percent chance that a 100-year...