FEMA Flood Data

Preliminary flood depth grid and other data relevant to the August 2016 flooding in south Louisiana has been released by FEMA and is available for online viewing and raw data download. These are in addition to maps and data released previously.

The majority of GIS data in FEMA's download folder are geodatabase (.gdb) files. It is my understanding that these are proprietary ESRI file formats requiring Spatial Analyst installed in addition to ArcGIS. I recommend the first link - the webmap - for those who do not have ESRI Spatial Analyst.

We understand that this data is a model of the extent of flooding and that work is ongoing to improve its accuracy. As an example of this I used the ArcGIS Online portal to zoom in on my home (the yellow square below) located in the Shenandoah neighborhood of East Baton Rouge Parish. The Amite River is to the right, and Jones Creek is the tributary across the top of the map. What I immediately noticed is that the actual flooding is, at least in some areas, worse than what these depth models show. I have depicted in blue several areas within my neighborhood that I observed to flood. This damage is also not evident on the NOAA aerial photography released yesterday because it was flown after the flood waters had largely receded from my neighborhood. The obvious explanation is that they couldn't fly it during the storms or cloud cover. Also, the depth model does not seem able to account for the municipal storm drainage infrastructure. I am blessed that water did not enter any homes on my street, but it did come close to entering a few on an adjacent street - Gaines Mill Avenue - and most of that water on Gaines Mill rose up through the storm drain system.

Example clip from FEMA preliminary flood depth grid map.