Flood Risk Map City of St Louis CDBG DR

Publication Date: 01/27/2025
Document Type: Meeting Materials
Sponsor: Community Development Administration

Summary
The 2022 Severe Storms and Flooding Event – Disaster Risk Reduction Areas were determined through a data informed process of locating sites impacted by three or more major flood risk characteristics.


The data used to identify flood risk characteristics:

-Federal Emergency Management Agency FEMA 100 & 500 Year Flood Zones

-Blocks Impacted by the 2022 Flood with over 3 feet of water reported.

-Problem Areas designated by the Metropolitan St. Louis Sewer District

-Historic & Modern Hydrologic Flow Paths


Federal Emergency Management Agency FEMA 100 & 500 Year Flood Zones:

Blocks Impacted by the 2022 Flood with over 3 feet of water reported - this is data of requests for help after the July 25, 2022 Flash Flood Disaster Event in St Louis. Data is from the City’s Emergency Management Agency and was derived from 2-1-1 / United Way Phone Calls and Online requests with a focus on “Amount of Water Damage” reports. Blocks people reported between 6” and + 3’ of water. This does not include the totality of requests for support or other sites which were impacted by the flood including people who didn’t know about 2-1-1, infrastructure such as metro stops, municipal and institutional buildings.

Problem Areas designated by the Metropolitan St. Louis Sewer District - the MSD problem areas identified by the Metropolitan St. Louis Sewer District (MSD) are based on decades of resident complaints and service requests.

Historic & Modern Hydrologic Flow Paths
1. The “modern streams” layer was made from a 2011 LiDAR image. LiDAR > DEM > Fill Elevation > Flow Direction > Flow Accumulation > CON Flow Accum (value > 500,000) > Stream Links > Stream to Feature This layer accounts for the changes to historic topography caused by street and building construction.
2. The “historic streams and lakes” layers show the historic hydrologic flow routes which are derived from elevation / topography data.