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DuPage County, IL 100 Yr Flood Plain Line

DuPage County, Illinois
  • Added 20 Sep 2018
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This layer is a component of REG Flood.

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.

Information

RegionsDuPage County

Technical Details

Layer ID 97711
Data type Vector linestring
Feature count 13735 (incl. 3 with empty or null geometries)
Attributes BOUNDARY,
Services Vector Query API

History

Added20 Sep 2018
Revisions 1 - Browse all revisions
Current revision Imported on Sept. 20, 2018 from Esri JSON in NAD83 / Illinois East (ftUS).
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