![]() The SFPUC used computer modeling that simulates flooding occurring Citywide under a 100-year storm to identify parcels that are likely to flood at least 6 inches in a 1% chance storm. A “100-year storm” means a storm with a 1% chance of occurring in a given year. ![]() The SFPUC has developed a 100-Year Storm Flood Risk Map (Flood Map) that shows areas of San Francisco where significant flooding from storm runoff is highly likely to occur during a 100-year storm. When this occurs, we can experience flooding that sometimes results in property damage. During extreme storms, storm runoff flows still follow the naturally-formed historical waterways. 100-Year Storm Flood Risk MapĪs San Francisco has developed over time, its hilly topography has been largely paved over. Inland limit of the area in an AE zone expected to receive 1.5-foot or greater breaking waves during the base flood event.Is your property at risk of flooding in a major rainstorm? Review our 100-year Storm Flood Risk Map, learn about legislation regarding property sale disclosures, and take advantage of our programs to help you prepare for and minimize impacts of heavy rains on your property. BFEs are provided.Ĭoastal areas subject to wave action greater than 3ft.Ĭoastal area subject to a velocity hazard (wave action greater than 3 ft.) where BFEs are not determined on the FIRM.Ĭoastal area subject to a velocity hazard (wave action greater than 3 ft.) where BFEs are provided on the FIRM.Īrea of moderate flood hazard, usually between the limits of the 1% annual chance flood (base flood or "100 -year flood") and the 0.2% annual chance flood ("500 -year flood") event.Īrea of minimal flood hazard, usually at elevation greater than the 0.2% annual chance flood ("500 year flood") event.Īrea of undetermined but possible flood hazards.ĭefined by LiMWA (Solid, Jagged Line- see example Here) Base flood depths (feet above ground) are provided. The base floodplain with sheet flow, ponding, or shallow flooding. (Current Format) The base floodplain where BFE is provided on the FIRM in parenthesis. The 1% annual chance floodplain, representing the "base flood" event (aka "100- year flood"). Check the map index for the BFE that corresponds to each zone number. The base floodplain mapped by approximate methods, i.e., BFEs are not determined.
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