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 publications associated with this project.
Assessment of the spatial extent and height of flooding in Lake Champlain during May 2011, using satellite remote sensing and ground-based information
Monitoring storm tide and flooding from Hurricane Sandy along the Atlantic coast of the United States, October 2012
Flood inundation map library, Fort Kent, Maine
Flood of April 2007 and Flood-Frequency Estimates at Streamflow-Gaging Stations in Western Connecticut
Flood of April 2007 in Southern Maine
Scoping of Flood Hazard Mapping Needs for Lincoln County, Maine
Estimated Magnitudes and Recurrence Intervals of Peak Flows on the Mousam and Little Ossipee Rivers for the Flood of April 2007 in Southern Maine
Scoping of Flood Hazard Mapping Needs for Hancock County, Maine
Scoping of Flood Hazard Mapping Needs for Penobscot County, Maine
Scoping of Flood Hazard Mapping Needs for Androscoggin County, Maine
Scoping of flood hazard mapping needs for Carroll County, New Hampshire
Scoping of flood hazard mapping needs for Belknap County, New Hampshire
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.
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
Below are publications associated with this project.
Filter Total Items: 17Assessment of the spatial extent and height of flooding in Lake Champlain during May 2011, using satellite remote sensing and ground-based information
Landsat 5 and moderate resolution imaging spectro-radiometer satellite imagery were used to map the area of inundation of Lake Champlain, which forms part of the border between New York and Vermont, during May 2011. During this month, the lake’s water levels were record high values not observed in the previous 150 years. Lake inundation area determined from the satellite imagery is correlated withAuthorsDavid M. Bjerklie, Thomas J. Trombley, Scott A. OlsonMonitoring storm tide and flooding from Hurricane Sandy along the Atlantic coast of the United States, October 2012
The U.S. Geological Survey (USGS) deployed a temporary monitoring network of water-level and barometric pressure sensors at 224 locations along the Atlantic coast from Virginia to Maine to continuously record the timing, areal extent, and magnitude of hurricane storm tide and coastal flooding generated by Hurricane Sandy. These records were greatly supplemented by an extensive post-flood high-wateAuthorsBrian E. McCallum, Shaun Wicklein, Robert G. Reiser, Ronald J. Busciolano, Jonathan Morrison, Richard J. Verdi, Jaime A. Painter, Eric R. Frantz, Anthony J. GotvaldFlood inundation map library, Fort Kent, Maine
Severe flooding occurred in northern Maine from April 28 to May 1, 2008, and damage was extensive in the town of Fort Kent (Lombard, 2010). Aroostook County was declared a Federal disaster area on May 9, 2008. The extent of flooding on both the Fish and St. John Rivers during this event showed that the current Federal Emergency Management Agency (FEMA) Flood Insurance Study (FIS) and Flood InsuranAuthorsPamela J. LombardFlood of April 2007 and Flood-Frequency Estimates at Streamflow-Gaging Stations in Western Connecticut
A spring nor'easter affected the East Coast of the United States from April 15 to 18, 2007. In Connecticut, rainfall varied from 3 inches to more than 7 inches. The combined effects of heavy rainfall over a short duration, high winds, and high tides led to widespread flooding, storm damage, power outages, evacuations, and disruptions to traffic and commerce. The storm caused at least 18 fatalitiesAuthorsElizabeth A. AhearnFlood of April 2007 in Southern Maine
Up to 8.5 inches of rain fell from April 15 through 18, 2007, in southern Maine. The rain - in combination with up to an inch of water from snowmelt - resulted in extensive flooding. York County, Maine, was declared a presidential disaster area following the event. The U.S. Geological Survey, in cooperation with the Federal Emergency Management Agency (FEMA), determined peak streamflows and recAuthorsPamela J. LombardScoping of Flood Hazard Mapping Needs for Lincoln County, Maine
Background The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public aAuthorsCharles W. Schalk, Robert W. DudleyEstimated Magnitudes and Recurrence Intervals of Peak Flows on the Mousam and Little Ossipee Rivers for the Flood of April 2007 in Southern Maine
Large amounts of rain fell on southern Maine from the afternoon of April 15, 2007, to the afternoon of April 16, 2007, causing substantial damage to houses, roads, and culverts. This report provides an estimate of the peak flows on two rivers in southern Maine--the Mousam River and the Little Ossipee River--because of their severe flooding. The April 2007 estimated peak flow of 9,230 ft3/s at theAuthorsGlenn A. Hodgkins, Gregory J. Stewart, Timothy A. Cohn, Robert W. DudleyScoping of Flood Hazard Mapping Needs for Hancock County, Maine
Background The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public aAuthorsCharles W. Schalk, Robert W. DudleyScoping of Flood Hazard Mapping Needs for Penobscot County, Maine
Background The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public aAuthorsCharles W. Schalk, Robert W. DudleyScoping of Flood Hazard Mapping Needs for Androscoggin County, Maine
Background The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public aAuthorsCharles W. Schalk, Robert W. DudleyScoping of flood hazard mapping needs for Carroll County, New Hampshire
This report was prepared by the U.S. Geological Survey (USGS) New Hampshire/Vermont Water Science Center for scoping of flood-hazard mapping needs for Carroll County, New Hampshire, under Federal Emergency Management Agency (FEMA) Inter-Agency agreement Number HSFE01-05X-0018. FEMA is embarking on a map modernization program nationwide to: 1. Gather and develop updated data for all flood proneAuthorsRobert H. FlynnScoping of flood hazard mapping needs for Belknap County, New Hampshire
This report was prepared by the U.S. Geological Survey (USGS) New Hampshire-Vermont Water Science Center for scoping of flood-hazard mapping needs for Belknap County, New Hampshire, under Federal Emergency Management Agency (FEMA) Inter-Agency agreement Number HSFE01-05X-0018.AuthorsRobert H. Flynn - 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...