topic Re: Issue Running Arc Hydro Identify Flat Areas tool in Water Resources Questions

Issue Running Arc Hydro Identify Flat Areas tool

drewb — Thu, 19 Feb 2026 01:56:11 GMT

I am attempting to create a flood depth raster so I can run the Flood Impact Analysis Solution (FIAS) toolset in my water district. I am following the Creating Flood Depth Rasters for Flood Impact Analysis guidance document, but am getting stuck on the addressing flat areas section. When I run the Arc Hydro Identify Flat Areas tool on the example DEM they provide, the tool completes successfully, but no rasters or layers are generated. I am using ArcGIS Pro 3.6.1.

Identify Flat Areas
=====================
Tool Path

Input DEM Raster dtm_extent1.tif
Flat Terrain Angle Threshold 1
Search Distance 10
Skip Distance 0
Flat Landform List Flat
Minimum Flat Area Threshold 2000 SquareMeters
Output Landform Raster C:\LOCATION\ArcHydro\FIAS\Layers\dtm_extent1_landform.tif
Output Flat Area Raster C:\LOCATION\ArcHydro\FIAS\Layers\dtm_extent1_flat.tif
Output Flat Area Polygon C:\LOCATION\ArcHydro\FIAS\FIAS.gdb\Layers\AHFlatPoly
=====================
Messages

Start Time: Wednesday, February 18, 2026 5:45:33 PM
Succeeded at Wednesday, February 18, 2026 5:45:34 PM (Elapsed Time: 0.75 seconds)

Re: Issue Running Arc Hydro Identify Flat Areas tool

DanPatterson — Thu, 19 Feb 2026 12:08:54 GMT

Are results automatically added to display for geoprocessing tools?

Have you confirmed that the 2 *.tif files don't exist in the output folders?

If they do exist and they are listed in the map's table of contents, do a right-click on one of the layers and zoom-to-layer (maybe a different ill-defined coordinate system)

Re: Issue Running Arc Hydro Identify Flat Areas tool

drewb — Thu, 19 Feb 2026 21:45:13 GMT

Hi Dan,

Thanks for your response. When I run the tool, no files are generated. I've checked the output locations and nothing appears, and nothing is added to the ToC.

Unfortunately, the AH download link that Dean shared in his response to the other post is broken. I will try to re-download my version of AH to see if that fixes anything.

Re: Issue Running Arc Hydro Identify Flat Areas tool

DanPatterson — Thu, 19 Feb 2026 22:24:26 GMT

Arc Hydro Tools Downloads for ArcGIS Pro & ArcMap

Downloading and Installing Arc Hydro Tools | 2023

hoping this is the download link access point

Re: Issue Running Arc Hydro Identify Flat Areas tool

drewb — Thu, 19 Feb 2026 22:37:18 GMT

Yes it is, thank you. Reinstalling did not seem to fix the issue. I did notice that the installation file states ArcHydroToolsforArcGISPro3.5.msi, so I am wondering if this is a versioning issue, since I am running ArcGIS Pro V3.6.1.

Re: Issue Running Arc Hydro Identify Flat Areas tool

DanPatterson — Fri, 20 Feb 2026 00:12:51 GMT

dont' know, but Arc Hydro Tools Downloads for ArcGIS Pro & ArcMap

says you have to request the download. I am not going to go through the steps to see if they have a version for 3.6