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Default [Illinois--DuPage County]

DuPage County GIS · 2020 Full Details

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Title
Default [Illinois--DuPage County]
Description
Special Flood Hazard Areas Inundated by the 1% Annual Chance Flood -The 1% annual chance flood (100-year), also known as the base flood, is the flood that has a 1% chance of being equaled or exceeded in any given year. The Special Flood Hazard Area is the area subject to flooding by the 1% annual chance flood. Areas of Special Flood Hazard inside DuPage County include Zones: A, AE, AH, and AO. The Base Flood Elevation is the water surface elevation of the 1% annual chance flood. Zone A - The flood insurance risk zone that corresponds to the 1% annual chance floodplains that are determined by approximate methods. Because detailed hydraulic analyses are not performed, no Base Flood Elevations (BFEs) or base flood depths are shown within this zone. Zone AE - The flood insurance risk zone that corresponds to the 1% annual chance floodplains that are determined by detailed methods. In most instances, whole-foot Base Flood Elevations (BFEs) derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Zone AH - The flood insurance risk zone that corresponds to the areas of 1& annual chance shallow flooding (usually areas of ponding) where average depths are between 1 and 3 feet. Whole-foot Base Flood Elevations (BFEs) derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Zone AO - The flood insurance risk zone that corresponds to the areas of 1& annual chance shallow flooding (usually sheet flow on sloping terrain) where average depths are between 1 and 3 feet. Average whole-foot base flood depths derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Floodway - A "Regulatory Floodway" means the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than 0.1 feet in height. Communities must regulate development in these floodways to ensure that there are no increases in upstream flood elevations. Other Flood Areas Zone X - The flood insurance risk zone that corresponds to areas outside the 0.2% annual chance floodplain, areas within the 0.2% annual chance floodplain, areas of 1% annual chance flooding where average depths are less than 1 foot, areas of 1% annual chance flooding where the contributing drainage areas is less than 1 square mile, and areas protected front the 1% annual chance flood by levees. No Base Flood Elevations (BFEs) or base flood depths are shown within this zone.
Creator
DuPage County Illinois
Publisher
DuPage County GIS
Temporal Coverage
Last Modified: 2020-01-06
Date Issued
2016-05-09
Access Rights
Public
Format
ArcGIS DynamicMapLayer
Language
English
Date Added
October 06, 2025
Provenance Statement
The metadata for this resource was last retrieved from DuPage County GIS on 2026-01-08.

Links

Cite and Reference

  • Citation
    DuPage County Illinois (2016). Default [Illinois--DuPage County]. DuPage County GIS. https://gisdata-dupage.opendata.arcgis.com/content/DuPage::default (web service)
  • BTAA Geoportal Link

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