About Global Flood Map

Climate change, globalization and urbanization are driving factors behind flood events and their consequences. As a company dedicated to helping its large commercial and industrial property clients manage their risk and operating resilience, FM Global has conducted extensive research and development—building on the experience and data from noted governmental and research organizations—to develop a Global Flood Map that identifies areas exposed to moderate- or high-hazard flooding. In addition to historical flood data, the Global Flood Map is derived from physically based hydrology and hydraulic scientific data, which accounts for variable external factors such as rainfall, evaporation, snowmelt and ground terrain. The Global Flood Map is particularly valuable in parts of the world where local or regional flood maps are inconsistent or not available. The Global Flood Map currently displays high (100-year) and moderate (500-year) hazard flood zones via a 90 meter x 90 meter grid.

Flood Zone Legend:

  • High Hazard (Pink)
    Locations in a 100-year flood zone have a 1 percent chance of experiencing a flood each year.
  • Moderate Hazard (Yellow)
    Locations in a 500-year flood zone have a 0.2 percent chance of experiencing a flood each year.

Frequently Asked Questions

Q: What makes our Global Flood Map unique?

A: The Global Flood Map is based on a physical model. The model recreates what actually happens when rain falls or snow melts by incorporating phenomena such as soil infiltration, water runoff and evaporation. This model is then calibrated against known river flows for accuracy.

Q: How should the Global Flood Map be used?

A: The Global Flood Map provides quick information on whether a location is in or out of a potential flood zone, and may be particularly helpful in searching areas of the world where other flood maps or resources are not readily available. It is an initial flood assessment tool which is not intended to replace more detailed local flood resources or a hydrological study. For more information on flood prevention, please refer to the FM Global Property Loss Prevention Data Sheet 1-40, Flood. You can subscribe to the FM Global Property Loss Prevention Data Sheets at www.fmglobal.com/datasheets. Flood abatement solutions, in the form of FM Approved products, can be found in our Approval Guide at approvalguide.com.

Q: Why does the flood map show “blocks” when zooming in?

A: FM Global has chosen to display the true resolution (i.e., the “blocky” appearance) with the grid data available. Although “smoothing” techniques could be applied to the contours to offer the appearance of higher resolution, it would be done at the expense of accuracy.

Q: Are all rivers and water conditions covered by the flood map?

A: No. Rivers with watersheds less than 39 square miles (101 square kilometers) are not included. The map also does not account for storm surges or local storm water runoffs. And like most flood maps, it does not recognize levees, bridges and culverts, and does not account for dams or reservoirs.

Q: The address I searched for is in a flood zone. What can I do?

A: FM Global offers guidance for flood prevention and mitigation in FM Global Property Loss Prevention Data Sheet 1-40, Flood. (Register to receive FM Global data sheets at fmglobal.com/datasheets. Flood abatement solutions, in the form of FM Approved products, can be found in our Approval Guide at approvalguide.com.)

Excluded Features

  • Storm surge and storm water runoff; rivers emptying into tidal waters assume high tide as boundary condition
  • Bridges, levees, dams, reservoirs and culverts
  • Rivers with watersheds less than 39 square miles (101 square kilometers)

Worldwide, excluding areas north of 60 degree latitude in North America, Asia, and Hawaii and small islands.

Digital Elevation Model Accuracy
Vertical elevation accuracy of +/- maximum 13 feet (4 meters) for Shuttle Radar Topography Mission, or fewer than 13 feet for other sources.

Vertical Datum
NAVD1988 in the United States, EDM96 GEOID elsewhere. Digital Elevation Model Data Source National Elevation Dataset (NED) in the U.S. ‎[1], National Finnish DTM in Finland ‎[2], ASTER in areas north of 60 degrees latitude outside of Finland ‎[3], Geoscience Australia 25 meters DEM in Australia ‎[4], and Shuttle Radar Topography Mission elsewhere ‎[5], all averaged at approximately 90 meter x 90 meter grid.

Used Hillslope River Routing (HRR) catchment-based hydrologic model, and 2D finite-volume hydrodynamic model with inundation areas delineated on a 90 meter x 90 meter grid.

Hydrologic Model Input Data
HydroSHEDS flow directions ‎[6], Precipitation CFS v2 NCEP ‎[7], GlobCover 2009 v2.3 for land cover ‎[8], and re-gridded HWSD v1.1 for soil ‎[9].

Visual Representation of River Centerlines
OpenStreetMap ‎[10]

USGS ‎[11], Global Runoff Data Centre (GRDC) ‎[12], and Satellite discharge data / River Watch ‎[13].

Data Sources

  1. U.S. Geological Survey, 2002, National Elevation Dataset. Retrieved in 2015.
  2. National Land Survey of Finland. Retrieved in February 2016.
  3. NASA LP DAAC, 2015, ASTER Level 1 Precision Terrain Corrected Registered At-Sensor Radiance. Version 3. NASA EOSDIS Land Processes DAAC, USGS Earth Resources Observation and Science (EROS) Center, Sioux Falls, South Dakota (https://lpdaac.usgs.gov), accessed January 1, 2014, at http://dx.doi.org/10.5067/ASTER/AST_L1T.003.
  4. Geoscience Australia (2015), Digital Elevation Model (DEM) 25 Metre Grid of Australia derived from LiDAR, GA: Canberra, ACT, Australia.
  5. USGS (2004), Shuttle Radar Topography Mission, all 3 Arc Second scenes, Filled Finished-B 2.0, Global Land Cover Facility, University of Maryland, College Park, Maryland, February 2000. These data are distributed by the Land Processes Distributed Active Archive Center (LP DAAC), located at USGS/EROS, Sioux Falls, South Dakota, USA. http://lpdaac.usgs.gov.
  6. Lehner, B., Verdin, K., Jarvis, A. (2008): New global hydrography derived from spaceborne elevation data. Eos, Transactions, AGU, 89(10): 93-94.
  7. Saha, S., et al. (2010), NCEP Climate Forecast System Reanalysis (CFSR) 6-hourly Products, January 1979 to December 2010, Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory, Boulder, Colorado, USA. Accessed January 1, 2012.
  8. The MODIS global land cover data product was retrieved from the online Data Pool, courtesy of the NASA Land Processes Distributed Active Archive Center (LP DAAC), USGS/Earth Resources Observation and Science (EROS) Center, Sioux Falls, South Dakota, USA. https://lpdaac.usgs.gov/data_access/data_pool
  9. Wieder, W.R., J. Boehnert, G.B. Bonan, and M. Langseth. 2014. Re-gridded Harmonized World Soil Database v1.2. Data set. Available online [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. http://dx.doi.org/10.3334/ORNLDAAC/1247
  10. OpenStreetMap contributors. E.T. Seton Park (Map). OpenStreetMap. Retrieved September 21, 2016.
  11. U.S. Geological Survey, 2015, National Water Information System data available on the World Wide Web (USGS Water Data for the Nation), accessed January 10, 2015, at http://waterdata.usgs.gov/nwis/.
  12. The Global Runoff Data Centre, 56068 Koblenz, Germany.
  13. Brakenridge, G.R., De Groeve, T., Kettner, A., Cohen, S., and Nghiem, S. V., date of display, River Watch, University of Colorado, Boulder, Colorado, USA http://floodobservatory.colorado.edu/DischargeAccess.html

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